Research related to this paper and the development of the fBFP technology in the Zhu lab were supported by NIH grants AI044902, AI077343, AI038282, HL093723, HL091020, GM096187, and TW008753. We thank Evan Evans for inventing this empowering experimental tool, and members of the Evans lab, Andrew Leung, Koji Kinoshita, Wesley Wong, and Ken Halvorsen, for helping us to build the BFP. We also thank other Zhu lab members, Fang Kong, Chenghao Ge and Kaitao Li, for their helps in the instrumentation development.

<ol>
	<li>Aplin, A. E., Howe, A., Alahari, S. K., Juliano, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signal+transduction+and+signal+modulation+by+cell+adhesion+receptors:+the+role+of+integrins,+cadherins,+immunoglobulin-cell+adhesion+molecules,+and+selectins.">Signal transduction and signal modulation by cell adhesion receptors: the role of integrins, cadherins, immunoglobulin-cell adhesion molecules, and selectins.</a> Pharmacological reviews. 50, 197-263 (1998).</li><li>Davis, M. M., Bjorkman, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T-cell+antigen+receptor+genes+and+T-cell+recognition.">T-cell antigen receptor genes and T-cell recognition.</a> Nature. 334, 395-402 (1988).</li><li>Dado, D., Sagi, M., Levenberg, S., Zemel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+control+of+stem+cell+differentiation.">Mechanical control of stem cell differentiation.</a> Regenerative medicine. 7, 101-116 (2012).</li><li>Edwards, L. J., Zarnitsyna, V. I., Hood, J. D., Evavold, B. D., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+into+T+cell+recognition+of+antigen:+significance+of+two-dimensional+kinetic+parameters.">Insights into T cell recognition of antigen: significance of two-dimensional kinetic parameters.</a> Frontiers in immunology. 3, 86 (2012).</li><li>Zhu, C., Jiang, N., Huang, J., Zarnitsyna, V. I., Evavold, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+from+in+situ+analysis+of+TCR-pMHC+recognition:+response+of+an+interaction+network.">Insights from in situ analysis of TCR-pMHC recognition: response of an interaction network.</a> Immunological reviews. 251, 49-64 (2013).</li><li>Huang, J., Meyer, C., Zhu, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+cell+antigen+recognition+at+the+cell+membrane.">T cell antigen recognition at the cell membrane.</a> Molecular immunology. 52, 155-164 (2012).</li><li>Zarnitsyna, V., Zhu, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+cell+triggering:+insights+from+2D+kinetics+analysis+of+molecular+interactions.">T cell triggering: insights from 2D kinetics analysis of molecular interactions.</a> Physical biology. 9, 045005 (2012).</li><li>Binnig, G., Quate, C. F., Gerber, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+Force+Microscope.">Atomic Force Microscope.</a> Physical Review Letters. 56, 930-933 (1986).</li><li>Marshall, B. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+observation+of+catch+bonds+involving+cell-adhesion+molecules.">Direct observation of catch bonds involving cell-adhesion molecules.</a> Nature. 423, 190-193 (2003).</li><li>Kong, F., Garcia, A. J., Mould, A. P., Humphries, M. J., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Demonstration+of+catch+bonds+between+an+integrin+and+its+ligand.">Demonstration of catch bonds between an integrin and its ligand.</a> The Journal of cell biology. 185, 1275-1284 (2009).</li><li>Yago, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catch+bonds+govern+adhesion+through+L-selectin+at+threshold+shear.">Catch bonds govern adhesion through L-selectin at threshold shear.</a> The Journal of cell biology. 166, 913-923 (2004).</li><li>Yago, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+glycoprotein+Ibalpha+forms+catch+bonds+with+human+WT+vWF+but+not+with+type+2B+von+Willebrand+disease+vWF.">Platelet glycoprotein Ibalpha forms catch bonds with human WT vWF but not with type 2B von Willebrand disease vWF.</a> The Journal of clinical investigation. 118, 3195-3207 (2008).</li><li>Chesla, S. E., Selvaraj, P., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+two-dimensional+receptor-ligand+binding+kinetics+by+micropipette.">Measuring two-dimensional receptor-ligand binding kinetics by micropipette.</a> Biophysical journal. 75, 1553-1572 (1998).</li><li>Huang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+kinetics+of+two-dimensional+TCR+and+pMHC+interactions+determine+T-cell+responsiveness.">The kinetics of two-dimensional TCR and pMHC interactions determine T-cell responsiveness.</a> Nature. 464, 932-936 (2010).</li><li>Heinrich, V., Wong, W. P., Halvorsen, K., Evans, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+biomolecular+interactions+by+fast+three-dimensional+tracking+of+laser-confined+carrier+particles.">Imaging biomolecular interactions by fast three-dimensional tracking of laser-confined carrier particles.</a> Langmuir : the ACS journal of surfaces and colloids. 24, 1194-1203 (2008).</li><li>Chen, W., Evans, E. A., McEver, R. P., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+receptor-ligand+interactions+between+surfaces+by+thermal+fluctuations.">Monitoring receptor-ligand interactions between surfaces by thermal fluctuations.</a> Biophysical journal. 94, 694-701 (2008).</li><li>Evans, E., Ritchie, K., Merkel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+force+technique+to+probe+molecular+adhesion+and+structural+linkages+at+biological+interfaces.">Sensitive force technique to probe molecular adhesion and structural linkages at biological interfaces.</a> Biophysical. 68, 2580-2587 (1995).</li><li>Evans, E., Leung, A., Heinrich, V., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+switching+and+coupling+between+two+dissociation+pathways+in+a+P-selectin+adhesion+bond.">Mechanical switching and coupling between two dissociation pathways in a P-selectin adhesion bond.</a> Proceedings of the National Academy of Sciences of the United States of America. 101, 11281-11286 (2004).</li><li>Ju, L., Dong, J. -. f., Cruz, M. A., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+N-terminal+Flanking+Region+of+the+A1+Domain+Regulates+the+Force-dependent+Binding+of+von+Willebrand+Factor+to+Platelet+Glycoprotein+Ib.">The N-terminal Flanking Region of the A1 Domain Regulates the Force-dependent Binding of von Willebrand Factor to Platelet Glycoprotein Ib.</a> Journal of Biological Chemistry. 288, (2013).</li><li>Chen, W., Lou, J., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forcing+switch+from+short-+to+intermediate-+and+long-lived+states+of+the+alphaA+domain+generates+LFA-1/ICAM-1+catch+bonds.">Forcing switch from short- to intermediate- and long-lived states of the alphaA domain generates LFA-1/ICAM-1 catch bonds.</a> The Journal of biological chemistry. 285, 35967-35978 (2010).</li><li>Chen, W., Lou, J., Evans, E. A., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observing+force-regulated+conformational+changes+and+ligand+dissociation+from+a+single+integrin+on+cells.">Observing force-regulated conformational changes and ligand dissociation from a single integrin on cells.</a> The Journal of cell biology. 199, 497-512 (2012).</li><li>Judokusumo, E., Tabdanov, E., Kumari, S., Dustin, M. L., Kam, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanosensing+in+T+lymphocyte+activation.">Mechanosensing in T lymphocyte activation.</a> Biophysical journal. 102, L5-L7 (2012).</li><li>Bashour, K. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD28+and+CD3+have+complementary+roles+in+T-cell+traction+forces.">CD28 and CD3 have complementary roles in T-cell traction forces.</a> Proceedings of the National Academy of Sciences of the United States of America. 111, 2241-2246 (2014).</li><li>Nesbitt, W. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+glycoprotein+Ib/V/IX+and+integrin+alpha+IIbbeta+3-dependent+calcium+signals+cooperatively+regulate+platelet+adhesion+under+flow.">Distinct glycoprotein Ib/V/IX and integrin alpha IIbbeta 3-dependent calcium signals cooperatively regulate platelet adhesion under flow.</a> The Journal of biological chemistry. 277, 2965-2972 (2002).</li><li>Mazzucato, M., Pradella, P., Cozzi, M. R., De Marco, L., Ruggeri, Z. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequential+cytoplasmic+calcium+signals+in+a+2-stage+platelet+activation+process+induced+by+the+glycoprotein+Ibalpha+mechanoreceptor.">Sequential cytoplasmic calcium signals in a 2-stage platelet activation process induced by the glycoprotein Ibalpha mechanoreceptor.</a> Blood. 100, 2793-2800 (2002).</li><li>Lefort, C. T., Ley, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+arrest+by+LFA-1+activation.">Neutrophil arrest by LFA-1 activation.</a> Frontiers in immunology. 3, 157 (2012).</li><li>Liu, B., Chen, W., Evavold, B. D., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accumulation+of+dynamic+catch+bonds+between+TCR+and+agonist+peptide-MHC+triggers+T+cell+signaling.">Accumulation of dynamic catch bonds between TCR and agonist peptide-MHC triggers T cell signaling.</a> Cell. 157, 357-368 (2014).</li><li>Lou, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow-enhanced+adhesion+regulated+by+a+selectin+interdomain+hinge.">Flow-enhanced adhesion regulated by a selectin interdomain hinge.</a> The Journal of cell biology. 174, 1107-1117 (2006).</li><li>Fiore, V. F., Ju, L., Chen, Y., Zhu, C., Barker, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+catch+of+a+Thy-1-alpha5beta1+syndecan-4+trimolecular+complex.">Dynamic catch of a Thy-1-alpha5beta1+syndecan-4 trimolecular complex.</a> Nature communications. 5, 4886 (2014).</li><li>Chen, W., Zarnitsyna, V. I., Sarangapani, K. K., Huang, J., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+Receptor-Ligand+Binding+Kinetics+on+Cell+Surfaces:+From+Adhesion+Frequency+to+Thermal+Fluctuation+Methods.">Measuring Receptor-Ligand Binding Kinetics on Cell Surfaces: From Adhesion Frequency to Thermal Fluctuation Methods.</a> Cellular and molecular bioengineering. 1, 276-288 (2008).</li><li>Marshall, B. T., Sarangapani, K. K., Lou, J., McEver, R. P., Zhu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Force+history+dependence+of+receptor-ligand+dissociation.">Force history dependence of receptor-ligand dissociation.</a> Biophysical. 88, 1458-1466 (2005).</li><li>Xiang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+basis+and+kinetics+of+force-induced+conformational+changes+of+an+alphaA+domain-containing+integrin.">Structural basis and kinetics of force-induced conformational changes of an alphaA domain-containing integrin.</a> PloS one. 6, e27946 (2011).</li></ol>

The authors have nothing to disclose.

성공적인 fBFP 실험은 몇 가지 중요한 고려 사항을 수반한다. 힘의 계산이 신뢰할 수있는 위해 첫째, 마이크로 피펫, RBC, 프로브 비드가 가능한 동축에 가깝게 정렬되어야합니다. RBC 및 피펫 사이의 마찰을 무시할 수 있도록 피펫 내부 RBC의 투영 약 1 프로브 피펫 직경이어야한다. 전형적인 사람 RBC 들어, 최적 피펫 직경 17,30 식 1의 최적을 산출 2.0-2.4 ㎛ 인 것이다. 둘째, 힘 클램프 분석 및 ?...

세포 간 및 세포 - 대 - 세포 외 기질 (ECM)의 밀착성이 세포 표면 수용체, ECM 단백질, 및 / 또는 지질 1 간의 결합에 의해 매개된다. 바인딩은 세포의 기능을 형성 한 구조뿐만 아니라, 인식, 통신, 및 환경 1-3에 반응 할 수있다. 수용성 단백질 (예 : 사이토킨 및 성장 인자), 3 차원 (3D)에서 결합하는 세포 표면 수용체 상 유체 상 달리 세포 부착 수용체 분자 구속 두 대향면을 연결하는 좁은 접합부 갭에 걸쳐 그들의 리간드 결합을 형성 두 차원 (2D) 인터페이스 4-7에 확산. 일반적으로 기존의 결합 분석 (예를 들어, 표면 플라즈몬 공명 또는 SPR)에 의해 측정되는 3D 동역학 달리, 챔버 (11, 12)을 흘러, 예컨대 원 자간 력 현미경 (AFM) 8-10 같은 전문 기술을 정량 2D 동력학 가지고 마이크로 피펫 13, 14, 광핀셋 (15)과 생체막의 힘 프로브 (BFP) 16-21. 단지 세포 응집력 물리적 링크를 제공하는 이상은, 부착 분자는 그 주변과 통신하는 셀에 대한 시그널링 장치의 주요 구성 요소이다. 부착 분자의 리간드 결합은 세포 내 신호 전달 및 방법은 초기 신호가 상기 형질 도입 된 세포의 내부를 개시한다 방법 이해에 관심이 증대되고있다. 직관적으로, 수용체 - 리간드의 성질은 그것이 유도 된 신호에 영향을 미칠 수 바​​인딩. 그러나, 그 때문에 예를 들면 많은 한계, 불량한 시간 해상도와 공간 해상도의 완전한 결핍의 생화학 적 분석법 전통적인 앙상블을 사용 세포 상호 작용 및 세포 내 신호 전달 기전 이벤트 간의 관계를 해부하기가 어렵다. 라이브에 모두 생물 물리학 (역학을 결합 2D 수용체 - 리간드)을 허용 방법과 생화학 (신호) 관측을 기존세포는 형광 기능을 24-26로 통합 조정 강성 (22)의 기판 (23) 엘라스토머 기둥 배열과 유량 용기 / 미세 유체 장치를 포함한다. 그러나, 신호와 결합 수용체 리간드의 판독이 어려운 신호 이벤트와 결합 특성의 공간적 관계를 해부하고, (다른 방법으로 가장 자주) 개별적으로 얻을 수있다. 기존의 BFP는 높은 시공간 해상도 (17)와 고감도 힘 분광법이다. 이는 단일 분자 동력학 2D, 기계적 특성 및 구조적 변화 14,16,19-21,27-29의 측정을 가능하게 힘 센서로서가요 적혈구 (RBC)를 사용한다. 형광 이미징 기반 BFP (fBFP)는 단일 분자 규모에서 결합 트리거 세포 신호와 수용체 - 리간드 결합 반응 속도의 상관 관계. 표면 mechani의 맥락에서 현장 세포 신호 활동이 설정으로CAL 자극은 T-27 세포에서 관찰되었다. fBFP 만능이며 다른 셀들에있는 다른 분자들에 의해 매개되는 세포 부착 및 시그널링의 연구에 사용될 수있다.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td colspan="4">Table 1: Reagents/Equipment</td>
		</tr>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>Sodium Phosphate Monobasic Monohydrate (NaH2PO4&#8226;H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>S9638</td>
			<td>Phosphate buffer preparation</td>
		</tr>
		<tr>
			<td>Anhy. Sodium Phosphate Dibasic (Na2HPO4)</td>
			<td>Sigma-Aldrich</td>
			<td>S7907</td>
			<td>Phosphate buffer preparation</td>
		</tr>
		<tr>
			<td>Sodium Carbonate (Na2CO3)</td>
			<td>Sigma-Aldrich</td>
			<td>S2127</td>
			<td>Carbonate/bicarbonate buffer preparation</td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate (NaHCO3)</td>
			<td>Sigma-Aldrich</td>
			<td>S5761</td>
			<td>Carbonate/bicarbonate buffer preparation</td>
		</tr>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>Sigma-Aldrich</td>
			<td>S7653</td>
			<td>N2-5% buffer preparation</td>
		</tr>
		<tr>
			<td>Potassium chloride (KCl)</td>
			<td>Sigma-Aldrich</td>
			<td>P9541</td>
			<td>N2-5% buffer preparation</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic (KH2PO4)</td>
			<td>Sigma-Aldrich</td>
			<td>P5655</td>
			<td>N2-5% buffer preparation</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich</td>
			<td>S0389</td>
			<td>N2-5% buffer preparation</td>
		</tr>
		<tr>
			<td>MAL-PEG3500-NHS</td>
			<td>JenKem</td>
			<td>A5002-1</td>
			<td>Bead functionalization</td>
		</tr>
		<tr>
			<td>Biotin-PEG3500-NHS</td>
			<td>JenKem</td>
			<td>A5026-1</td>
			<td>RBC biotinylation</td>
		</tr>
		<tr>
			<td>Nystatin</td>
			<td>Sigma-Aldrich</td>
			<td>N6261</td>
			<td>RBC osmolarity adjustment</td>
		</tr>
		<tr>
			<td>Ammonium Hydroxide (NH4OH)</td>
			<td>Sigma-Aldrich</td>
			<td>A-6899</td>
			<td>Glass bead silanization</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>BDH</td>
			<td>67-56-1</td>
			<td>Glass bead silanization</td>
		</tr>
		<tr>
			<td>30% Hydrogen Peroxide (H2O2)</td>
			<td>J. T. Barker</td>
			<td>Jan-86</td>
			<td>Glass bead silanization</td>
		</tr>
		<tr>
			<td>Acetic Acid (Glacial)</td>
			<td>Sigma-Aldrich</td>
			<td>ARK2183</td>
			<td>Glass bead silanization</td>
		</tr>
		<tr>
			<td>3-MERCAPTOPROPYLTRIMETHOXYSILANE(MPTMS)</td>
			<td>Uct Specialties, llc</td>
			<td>4420-74-0</td>
			<td>Glass bead functionalization</td>
		</tr>
		<tr>
			<td>Borosilicate Glass beads</td>
			<td>Distrilab Particle Technology</td>
			<td>9002</td>
			<td>Glass bead functionalization</td>
		</tr>
		<tr>
			<td>Streptavidin&#8722;Maleimide</td>
			<td>Sigma-Aldrich</td>
			<td>S9415</td>
			<td>Glass bead functionalization</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Sigma-Aldrich</td>
			<td>A0336</td>
			<td>Ligand functionalizing</td>
		</tr>
		<tr>
			<td>Fura2-AM</td>
			<td>Life Technologies</td>
			<td>F-1201</td>
			<td>Intracellular calcium fluorescence dye loading</td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide (DMSO)</td>
			<td>Sigma-Aldrich</td>
			<td>D2650</td>
			<td>Intracellular calcium fluorescence dye loading</td>
		</tr>
		<tr>
			<td>Quantibrite PE Beads</td>
			<td>BD Biosciences</td>
			<td>340495</td>
			<td>Density quantification</td>
		</tr>
		<tr>
			<td>Flow Cytometer</td>
			<td>BD Biosciences</td>
			<td>BD LSR II</td>
			<td>Density quantification</td>
		</tr>
		<tr>
			<td>Capillary Tube 0.7-1.0mm x 30&#34;</td>
			<td>Kimble Chase</td>
			<td>46485-1</td>
			<td>Micropipette making</td>
		</tr>
		<tr>
			<td>Flaming/Brown Micropipette Puller</td>
			<td>sutter instrument</td>
			<td>P-97</td>
			<td>Micropipette making</td>
		</tr>
		<tr>
			<td>Pipette microforce</td>
			<td>Narishige</td>
			<td>MF-900</td>
			<td>Micropipette making</td>
		</tr>
		<tr>
			<td>Mineral Oil</td>
			<td>Fisher Scientific</td>
			<td>BP2629-1</td>
			<td>Chamber assembly</td>
		</tr>
		<tr>
			<td>Microscope Cover Glass</td>
			<td>Fisher Scientific</td>
			<td>12-544-G</td>
			<td>Chamber assembly</td>
		</tr>
		<tr>
			<td>Micro-injector</td>
			<td>World Precision Instruments</td>
			<td>MF34G-5</td>
			<td>Chamber assembly</td>
		</tr>
		<tr>
			<td>1ml Syringe</td>
			<td>BD&#160;</td>
			<td>309602</td>
			<td>Chamber assembly</td>
		</tr>
		<tr>
			<td>Micropipette holder</td>
			<td>Narishige</td>
			<td>HI-7</td>
			<td>Chamber assembly</td>
		</tr>
		<tr>
			<td>Home-designed mechanical parts and adaptors fabrications using CNC machining.&#160;</td>
			<td>Biophysics Instrument</td>
			<td>All parts are customized according to the CAD designs.</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Microscope (TiE inverted)</td>
			<td>Nikon</td>
			<td>MEA53100</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Objective CFI Plan Fluor 40x (NA 0.75, WD 0.72mm, Spg)</td>
			<td>Nikon</td>
			<td>MRH00401</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Camera, GE680, 640x480, GigE, 1/3&#34; CCD, mono</td>
			<td>Graftek Imaging</td>
			<td>02-2020C</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Prosilica GC1290 - ICX445, 1/3&#34;, C-Mount, 1280x960, Mono., CCD, 12 Bit ADC</td>
			<td>Graftek Imaging</td>
			<td>02-2185A</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Manual submicron probehead with high resolution remote control</td>
			<td>Karl Suss</td>
			<td>PH400</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Anti-vibration table (5&#8217; x 3&#8217;)</td>
			<td>TMC</td>
			<td>77049089</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>3D manual translational stage</td>
			<td>Newport</td>
			<td>462-XYZ-M</td>
			<td></td>
		</tr>
		<tr>
			<td>SolidWorks 3D CAD software</td>
			<td>SOLIDWORKS Corp.</td>
			<td>Version 2012 SP5</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>LabVIEW software</td>
			<td>National Instruments</td>
			<td>Version 2009</td>
			<td>BFP system, BFP program</td>
		</tr>
		<tr>
			<td>3D piezo translational stage</td>
			<td>Physik Instrumente</td>
			<td>M-105.3P</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Linear piezo accuator</td>
			<td>Physik Instrumente</td>
			<td>P-753.1CD</td>
			<td>BFP system</td>
		</tr>
		<tr>
			<td>Micromanager software</td>
			<td></td>
			<td>Version 1.4</td>
			<td>fBFP system, fluorescence imaging program</td>
		</tr>
		<tr>
			<td>Dual Cam (DC-2)</td>
			<td>Photometrics</td>
			<td>77054724</td>
			<td>fBFP system</td>
		</tr>
		<tr>
			<td>Dual Cam emission filter (T565LPXR)</td>
			<td>Photometrics</td>
			<td>77054725</td>
			<td>fBFP system</td>
		</tr>
		<tr>
			<td>Fluorescence Camera</td>
			<td>Hamamatsu</td>
			<td>ORCA-R2 C10600-10B</td>
			<td>fBFP system</td>
		</tr>
		<tr>
			<td>Plastic paraffin film (Parafilm)</td>
			<td>Bemis Company, Inc</td>
			<td>PM996</td>
			<td>bottle sealing</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="2">Table 2: Buffer solutions</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Carbonate/bicarbonate buffer (pH 8.5)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Carbonate (Na2CO3)</td>
			<td>8.4g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate (NaHCO3)</td>
			<td>10.6g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffer (pH 6.5-6.8)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaPhosphate monobasic&#160;&#160;&#160;NaH2PO4&#8226;H2O</td>
			<td>27.6g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anhy. NaPhosphate dibasic&#160;&#160; Na2HPO4</td>
			<td>28.4g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>N2-5% buffer (pH 7.2)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride (KCl)</td>
			<td>20.77g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>2.38g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic (KH2PO4)</td>
			<td>0.13g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anhy. Sodium Phosphate Dibasic (Na2HPO4)</td>
			<td>0.71g/L</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>9.70g/L</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

fluorescence biomembrane force probe: concurrent quantitation of receptor-ligand kinetics and binding-induced intracellular signaling on a single cell

멤브레인 수용체 - 리간드 상호 작용은 다수의 세포 기능을 매개한다. 바인딩 역학 이러한 분자의 상호 작용에 의해 트리거 다운 스트림 신호는 가능성이 기계적인 환경에서 결합 및 신호 포획 장소에 의해 영향을받습니다. 최근 연구는 기계적인 힘에 의한 항원 인식을 조절하고 T 세포 수용체 (TCR)의 트리거링 할 것을 보여 주었다. 이 형광 현미경으로 단일 분자 힘 분광법을 결합한 새로운 우리가 개발 한 기술이라고 형광 생체막의 힘 프로브 (fBFP)에 의해 가능하게되었다. 민감한 힘 센서로서 고속 카메라와 실시간 영상 추적 기술을 매우 부드러운 인간 적혈구를 사용 fBFP 1 ~ PN (10-12 N) ~ 3nm 이상이며 ~ 0.5 밀리의 힘, 공간과 시간 해상도. fBFP으로, 하나는 정확하게 힘 조절에 따라 단일 수용체 - 리간드 결합 동력학과 동시​​에 이미지가 트리거 바인딩 세포 내 칼을 측정 할 수 있습니다cium 하나의 살아있는 세포에 신호. 이 새로운 기술은 기계적인 규제에서 다른 세포에서 다른 막 수용체 - 리간드 상호 작용과 신호 전달을 연구하는 데 사용할 수 있습니다.

BFP 기술 1995 17 에반스 실험실에 의해 개척되었다.이 picoforce 도구는 광범위하게, 그들의 리간드 16,19,20과 상호 작용하는 부착 분자의 이차원 동력학을 분석하기 위하여, 표면에 고정화 된 단백질의 상호 작용을 측정하기 위해 사용 된 30, 분자 탄성 21,29을 측정하고, 단백질의 구조적 (21)을 변경 결정합니다. 대한 fBFP, 추가되는 해당 소프트웨어 시스?...

Watch this Scientific Journal Video about Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell at JoVE

Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell

We describe a technique for concurrently measuring force-regulated single receptor-ligand binding kinetics and real-time imaging of calcium signaling in a single T lymphocyte.

형광 생체막 포스 프로브 : 하나의 세포에서 수용체 - 리간드 속도론의 동시 정량 및 바인딩에 의한 세포 내 신호

Membrane receptor-ligand interactions mediate many cellular functions. Binding kinetics and downstream signaling triggered by these molecular interactions ...

fluorescence-biomembrane-force-probe-concurrent-quantitation-receptor

Research

JoVE Journal

Bioengineering

12.3K 조회수.  Georgia Institute of Technology. We describe a technique for concurrently measuring force-regulated single receptor-ligand binding kinetics and real-time imaging of calcium signaling in a single T lymphocyte.

비디오: Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell

Time-lapse Fluorescence Imaging of Arabidopsis Root Growth with Rapid Manipulation of The Root Environment Using The RootChip

The root functions as the physical anchor of the plant and is the organ responsible for uptake of water and mineral nutrients such as nitrogen, phosphorus, sulfate and trace elements that plants acquire from the soil. If we want to develop sustainable approaches to producing high crop yield, we need to better understand how the root develops, takes up a wide spectrum of nutrients, and interacts with symbiotic and pathogenic organisms. To accomplish these goals, we need to be able to explore roots in microscopic detail over time periods ranging from minutes to days.
We developed the RootChip, a polydimethylsiloxane (PDMS)- based microfluidic device, which allows us to grow and image roots from Arabidopsis seedlings while avoiding any physical stress to roots during preparation for imaging1 (Figure 1). The device contains a bifurcated channel structure featuring micromechanical valves to guide the fluid flow from solution inlets to each of the eight observation chambers2. This perfusion system allows the root microenvironment to be controlled and modified with precision and speed. The volume of the chambers is approximately 400 nl, thus requiring only minimal amounts of test solution.
Here we provide a detailed protocol for studying root biology on the RootChip using imaging-based approaches with real time resolution. Roots can be analyzed over several days using time lapse microscopy. Roots can be perfused with nutrient solutions or inhibitors, and up to eight seedlings can be analyzed in parallel. This system has the potential for a wide range of applications, including analysis of root growth in the presence or absence of chemicals, fluorescence-based analysis of gene expression, and the analysis of biosensors, e.g. FRET nanosensors3.

This article provides a protocol for cultivation of Arabidopsis seedlings in the RootChip, a microfluidic imaging platform that combines automated control of growth conditions with microscopic root monitoring and FRET-based measurement of intracellular metabolite levels.

RootChip를 사용하여 루트 환경의 신속한 조작과 Arabidopsis 루트 성장의 시간 저속 형광 이미징

The root functions as the physical anchor of the plant and is the organ responsible for uptake of water and mineral nutrients such as nitrogen, ...

연구

생체공학

Investigating Receptor-ligand Systems of the Cellulosome with AFM-based Single-molecule Force Spectroscopy

Cellulosomes are discrete multienzyme complexes used by a subset of anaerobic bacteria and fungi to digest lignocellulosic substrates. Assembly of the enzymes onto the noncatalytic scaffold protein is directed by interactions among a family of related receptor-ligand pairs comprising interacting cohesin and dockerin modules. The extremely strong binding between cohesin and dockerin modules results in dissociation constants in the low picomolar to nanomolar range, which may hamper accurate off-rate measurements with conventional bulk methods. Single-molecule force spectroscopy (SMFS) with the atomic force microscope measures the response of individual biomolecules to force, and in contrast to other single-molecule manipulation methods (i.e.&#160;optical tweezers), is optimal for studying high-affinity receptor-ligand interactions because of its ability to probe the high-force regime (&#62;120 pN). Here we present our complete protocol for studying cellulosomal protein assemblies at the single-molecule level. Using a protein topology derived from the native cellulosome, we worked with enzyme-dockerin and carbohydrate binding module-cohesin (CBM-cohesin) fusion proteins, each with an accessible free thiol group at an engineered cysteine residue. We present our site-specific surface immobilization protocol, along with our measurement and data analysis procedure for obtaining detailed binding parameters for the high-affinity complex. We demonstrate how to quantify single subdomain unfolding forces, complex rupture forces, kinetic off-rates, and potential widths of the binding well. The successful application of these methods in characterizing the cohesin-dockerin interaction responsible for assembly of multidomain cellulolytic complexes is further described.

Cellulosomes are multienzyme complexes designed for digesting cellulose. AFM-based SMFS was used to study the mechanical properties and folding configuration of cellulosome-associated protein assemblies. We present a complete workflow for protein immobilization, data acquisition, and data analysis to study the interactions of individual receptor-ligand complexes involved in cellulosome assembly.

Cellulosomes are discrete multienzyme complexes used by a subset of anaerobic bacteria and fungi to digest lignocellulosic substrates. Assembly of the ...

Cell Squeezing as a Robust, Microfluidic Intracellular Delivery Platform

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This technology has shown potential in addressing previously challenging applications; including, delivery to primary immune cells, cell reprogramming, carbon nanotube, and quantum dot delivery. This vector-free microfluidic platform relies on mechanical disruption of the cell membrane to facilitate cytosolic delivery of the target material. Herein, we describe the detailed method of use for these microfluidic devices including, device assembly, cell preparation, and system operation. This delivery approach requires a brief optimization of device type and operating conditions for previously unreported applications. The provided instructions are generalizable to most cell types and delivery materials as this system does not require specialized buffers or chemical modification/conjugation steps. This work also provides recommendations on how to improve device performance and trouble-shoot potential issues related to clogging, low delivery efficiencies, and cell viability.

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This protocol provides detailed steps on how to use the system for a broad range of applications.

강력한, 미세 유체 세포 내 전달 플랫폼으로 휴대 뒤쪽에서

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This ...

A Microfluidic Technique to Probe Cell Deformability

Here we detail the design, fabrication, and use of a microfluidic device to evaluate the deformability of a large number of individual cells in an efficient manner. Typically, data for ~102 cells can be acquired within a 1 hr experiment. An automated image analysis program enables efficient post-experiment analysis of image data, enabling processing to be complete within a few hours. Our device geometry is unique in that cells must deform through a series of micron-scale constrictions, thereby enabling the initial deformation and time-dependent relaxation of individual cells to be assayed. The applicability of this method to human promyelocytic leukemia (HL-60) cells is demonstrated. Driving cells to deform through micron-scale constrictions using pressure-driven flow, we observe that human promyelocytic (HL-60) cells momentarily occlude the first constriction for a median time of 9.3 msec before passaging more quickly through the subsequent constrictions with a median transit time of 4.0 msec per constriction. By contrast, all-trans retinoic acid-treated (neutrophil-type) HL-60 cells occlude the first constriction for only 4.3 msec before passaging through the subsequent constrictions with a median transit time of 3.3 msec. This method can provide insight into the viscoelastic nature of cells, and ultimately reveal the molecular origins of this behavior.

We demonstrate a microfluidics-based assay to measure the timescale for cells to transit through a sequence of micron-scale constrictions.

미세 유체 기술은 셀 변형능을 검사 할

Here we detail the design, fabrication, and use of a microfluidic device to evaluate the deformability of a large number of individual cells in an ...

Formation of Biomembrane Microarrays with a Squeegee-based Assembly Method

Lipid bilayer membranes form the plasma membranes of cells and define the boundaries of subcellular organelles. In nature, these membranes are heterogeneous mixtures of many types of lipids, contain membrane-bound proteins and are decorated with carbohydrates. In some experiments, it is desirable to decouple the biophysical or biochemical properties of the lipid bilayer from those of the natural membrane. Such cases call for the use of model systems such as giant vesicles, liposomes or supported lipid bilayers (SLBs). Arrays of SLBs are particularly attractive for sensing applications and mimicking cell-cell interactions. Here we describe a new method for forming SLB arrays. Submicron-diameter SiO2 beads are first coated with lipid bilayers to form spherical SLBs (SSLBs). The beads are then deposited into an array of micro-fabricated submicron-diameter microwells. The preparation technique uses a "squeegee" to clean the substrate surface, while leaving behind SSLBs that have settled into microwells. This method requires no chemical modification of the microwell substrate, nor any particular targeting ligands on the SSLB. Microwells are occupied by single beads because the well diameter is tuned to be just larger than the bead diameter. Typically, more 75% of the wells are occupied, while the rest remain empty. In buffer SSLB arrays display long-term stability of greater than one week. Multiple types of SSLBs can be placed in a single array by serial deposition, and the arrays can be used for sensing, which we demonstrate by characterizing the interaction of cholera toxin with ganglioside GM1. We also show that phospholipid vesicles without the bead supports and biomembranes from cellular sources can be arrayed with the same method and cell-specific membrane lipids can be identified.

Supported lipid bilayers and natural membrane particles are convenient systems that can approximate the properties of cell membranes and be incorporated in a variety of analytical strategies. Here we demonstrate a method for preparing microarrays composed of supported lipid bilayer-coated SiO2 beads, phospholipid vesicles or natural membrane particles.

스퀴지 기반의 조립 방법과 생체막 마이크로 어레이의 형성

Lipid bilayer membranes form the plasma membranes of cells and define the boundaries of subcellular organelles. In nature, these membranes are ...

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a modified two-photon microscope1. As opposed to conventional approaches (raster scan or wide field based on a stack of frames), the 3D orbital tracking allows to localize and follow with a high spatial (10 nm accuracy) and temporal resolution (50 Hz frequency response) the 3D displacement of a moving fluorescent particle on length-scales of hundreds of microns2. The method is based on a feedback algorithm that controls the hardware of a two-photon laser scanning microscope in order to perform a circular orbit around the object to be tracked: the feedback mechanism will maintain the fluorescent object in the center by controlling the displacement of the scanning beam3-5. To demonstrate the advantages of this technique, we followed a fast moving organelle, the lysosome, within a living cell6,7. Cells were plated according to standard protocols, and stained using a commercially lysosome dye. We discuss briefly the hardware configuration and in more detail the control software, to perform a 3D orbital tracking experiment inside living cells. We discuss in detail the parameters required in order to control the scanning microscope and enable the motion of the beam in a closed orbit around the particle. We conclude by demonstrating how this method can be effectively used to track the fast motion of a labeled lysosome along microtubules in 3D within a live cell. Lysosomes can move with speeds in the range of 0.4-0.5 &#181;m/sec, typically displaying a directed motion along the microtubule network8.

In this video protocol we track - at high speed and in three dimensions - fluorescently labeled lysosomes within living cells, using the orbital tracking method in a modified two-photon microscope.

수정 된 두 개의 광자 현미경에서 3D 궤도 추적 : 세포 내 소포의 추적에 응용

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a ...

From Fast Fluorescence Imaging to Molecular Diffusion Law on Live Cell Membranes in a Commercial Microscope

It has become increasingly evident that the spatial distribution and the motion of membrane components like lipids and proteins are key factors in the regulation of many cellular functions. However, due to the fast dynamics and the tiny structures involved, a very high spatio-temporal resolution is required to catch the real behavior of molecules. Here we present the experimental protocol for studying the dynamics of fluorescently-labeled plasma-membrane proteins and lipids in live cells with high spatiotemporal resolution. Notably, this approach doesn&#8217;t need to track each molecule, but it calculates population behavior using all molecules in a given region of the membrane. The starting point is a fast imaging of a given region on the membrane. Afterwards, a complete spatio-temporal autocorrelation function is calculated correlating acquired images at increasing time delays, for example each 2, 3, n repetitions. It is possible to demonstrate that the width of the peak of the spatial autocorrelation function increases at increasing time delay as a function of particle movement due to diffusion. Therefore, fitting of the series of autocorrelation functions enables to extract the actual protein mean square displacement from imaging (iMSD), here presented in the form of apparent diffusivity vs average displacement. This yields a quantitative view of the average dynamics of single molecules with nanometer accuracy. By using a GFP-tagged variant of the Transferrin Receptor (TfR) and an ATTO488 labeled 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphoethanolamine (PPE) it is possible to observe the spatiotemporal regulation of protein and lipid diffusion on &#181;m-sized membrane regions in the micro-to-milli-second time range.

Spatial distribution and temporal dynamics of plasma membrane proteins and lipids is a hot topic in biology. Here this issue is addressed by a spatio-temporal image fluctuation analysis that provides conceptually the same physical quantities of single particle tracking, but it uses small molecular labels and standard microscopy setups.

상용 현미경에서 라이브 세포막에 분자 확산 법률에 빠른 형광 이미징

It has become increasingly evident that the spatial distribution and the motion of membrane components like lipids and proteins are key factors in the ...

Surface Potential Measurement of Bacteria Using Kelvin Probe Force Microscopy

Surface potential is a commonly overlooked physical characteristic that plays a dominant role in the adhesion of microorganisms to substrate surfaces. Kelvin probe force microscopy (KPFM) is a module of atomic force microscopy (AFM) that measures the contact potential difference between surfaces at the nano-scale. The combination of KPFM with AFM allows for the simultaneous generation of surface potential and topographical maps of biological samples such as bacterial cells. Here, we employ KPFM to examine the effects of surface potential on microbial adhesion to medically relevant surfaces such as stainless steel and gold. Surface potential maps revealed differences in surface potential for microbial membranes on different material substrates. A step-height graph was generated to show the difference in surface potential at a boundary area between the substrate surface and microorganisms. Changes in cellular membrane surface potential have been linked with changes in cellular metabolism and motility. Therefore, KPFM represents a powerful tool that can be utilized to examine the changes of microbial membrane surface potential upon adhesion to various substrate surfaces. In this study, we demonstrate the procedure to characterize the surface potential of individual methicillin-resistant Staphylococcus aureus USA100 cells on stainless steel and gold using KPFM.

Here, we present a protocol explaining the use of Kelvin probe force microscopy as a tool for generating high resolution nano-scale surface potential maps. This tool was applied to assess the role of surface potential on the binding capacity of microorganisms to substrate surfaces.

켈빈 프로브 힘 현미경을 사용하여 박테리아의 표면 전위 측정

Surface potential is a commonly overlooked physical characteristic that plays a dominant role in the adhesion of microorganisms to substrate surfaces. ...

Biomembrane Fabrication by the Solvent-assisted Lipid Bilayer (SALB) Method

In order to mimic cell membranes, the supported lipid bilayer (SLB) is an attractive platform which enables in vitro investigation of membrane-related processes while conferring biocompatibility and biofunctionality to solid substrates. The spontaneous adsorption and rupture of phospholipid vesicles is the most commonly used method to form SLBs. However, under physiological conditions, vesicle fusion (VF) is limited to only a subset of lipid compositions and solid supports. Here, we describe a one-step general procedure called the solvent-assisted lipid bilayer (SALB) formation method in order to form SLBs which does not require vesicles. The SALB method involves the deposition of lipid molecules onto a solid surface in the presence of water-miscible organic solvents (e.g., isopropanol) and subsequent solvent-exchange with aqueous buffer solution in order to trigger SLB formation. The continuous solvent exchange step enables application of the method in a flow-through configuration suitable for monitoring bilayer formation and subsequent alterations using a wide range of surface-sensitive biosensors. The SALB method can be used to fabricate SLBs on a wide range of hydrophilic solid surfaces, including those which are intractable to vesicle fusion. In addition, it enables fabrication of SLBs composed of lipid compositions which cannot be prepared using the vesicle fusion method. Herein, we compare results obtained with the SALB and conventional vesicle fusion methods on two illustrative hydrophilic surfaces, silicon dioxide and gold. To optimize the experimental conditions for preparation of high quality bilayers prepared via the SALB method, the effect of various parameters, including the type of organic solvent in the deposition step, the rate of solvent exchange, and the lipid concentration is discussed along with troubleshooting tips. Formation of supported membranes containing high fractions of cholesterol is also demonstrated with the SALB method, highlighting the technical capabilities of the SALB technique for a wide range of membrane configurations.

Biomembrane Fabrication by the Solvent-assisted Lipid Bilayer SALB Method

We present an experimental protocol to form a supported lipid bilayer on solid substrates without using lipid vesicles. We demonstrate a one-step method to form a lipid bilayer on silicon dioxide and gold as well as supported membranes with cholesterol-enriched domain for various biological applications.

용매를 이용한 지질 이중층 (SALB) 방법에 의해 생체막 제작

In order to mimic cell membranes, the supported lipid bilayer (SLB) is an attractive platform which enables in vitro investigation of membrane-related ...

Single Molecule Fluorescence Microscopy on Planar Supported Bilayers

In the course of a single decade single molecule microscopy has changed from being a secluded domain shared merely by physicists with a strong background in optics and laser physics to a discipline that is now enjoying vivid attention by life-scientists of all venues 1. This is because single molecule imaging has the unique potential to reveal protein behavior in situ in living cells and uncover cellular organization with unprecedented resolution below the diffraction limit of visible light 2. Glass-supported planar lipid bilayers (SLBs) are a powerful tool to bring cells otherwise growing in suspension in close enough proximity to the glass slide so that they can be readily imaged in noise-reduced Total Internal Reflection illumination mode 3,4. They are very useful to study the protein dynamics in plasma membrane-associated events as diverse as cell-cell contact formation, endocytosis, exocytosis and immune recognition. Simple procedures are presented how to generate highly mobile protein-functionalized SLBs in a reproducible manner, how to determine protein mobility within and how to measure protein densities with the use of single molecule detection. It is shown how to construct a cost-efficient single molecule microscopy system with TIRF illumination capabilities and how to operate it in the experiment.

Preparation of protein-functionalized planar glass-supported lipid bilayers, determination of protein mobility within and measurement of protein densities is shown here. A roadmap to building a noise-reduced Total Internal Reflection microscope is outlined, which allows visualizing single bilayer-resident fluorochromes with high spatiotemporal resolution.

평면에 단일 분자 형광 현미경은 이중층 지원

In the course of a single decade single molecule microscopy has changed from being a secluded domain shared merely by physicists with a strong background ...