저자는 우리의 연구 노력을 장려하기위한 버지니아 기술 캐릴리온 연구소의 이사 마이클 J. 프리들랜더 박사를 인정합니다. 이 프로젝트는 S.M.M 및 D.F.K.에 대한 개발 기금에 의해 지원되었으며 버지니아 공대의 중요 기술 및 응용 과학 연구소의 나노 바이오 이니셔티브에 의해 부분적으로 지원되었습니다.

1. 선호도 캡처 장치 준비장치16
<ol><li>실리콘 질화물 E 칩을 15 ml의 아세톤으로 2 분 동안 배양하고 2 분 동안 메탄올 15 ml(그림 1A)를청소하십시오. 칩이 라미나르 공기 흐름 아래에서 건조하도록 허용합니다.</li>
	<li>150°C에서 1.5시간 동안 가열된 교반판에 말린 칩을 배양한 다음 사용하기 전에 실온으로 식힙니다.</li>
	<li>해밀턴 주사기를 사용하여 작은 유리 튜브에 지질 혼합물을 구성하여 25 % 클로로폼을 함유하고, 클로로폼(1mg/ml)의 55%의 DLPC(1,2-딜라우로일-인포콜린)와 20% Ni-NTA 지질(1,2-디오틸-이미노이아세트산-succinyl-니켈 소금)을 총 40μl의 부피량에 대해 클로로폼(1 mg/ml)이다.</li>
	<li>습한 페트리접시(그림 1B)에서파라필름 조각에 밀리-Q 물 15μl 방울에 혼합물의 1 μl 알리쿼트를 적용한다. 얼음에 샘플을 60분 이상 배양합니다.</li>
</ol>2. 매크로 분자 캡처17
<ol><li>단층 샘플 위에 150 nm 통합 스페이서가 있는 E 칩을 1분 동안 배양한다(그림1C).</li>
	<li>시료의 칩을 부드럽게 들어 올리고 실온에서 1 분 동안 그의 태그 된 단백질 A. 인큐베이터의 3 μl 알리쿼트(그림 1D)를추가합니다.</li>
	<li>Whatman #1 필터 용지를 사용하여 초과 낙하를 블롯하고 즉시 항체 용액의 3 μl 알리쿼트를 추가합니다. 실온에서 1분 동안 배양하십시오.</li>
	<li>해밀턴 주사기를 사용하여 초과 용액을 제거하고 즉시 50mM HEPES (pH 7.5), 150 mM M NaCl, 10mM MgCl2 및 10mM CaCl2를포함하는 버퍼 용액에 로타 바이러스 DLP (0.1 mg /ml)의 1 μl 알리쿼트를 추가합니다. 실온에서 최소 2분 동안 배양하십시오. DlP의 준비는 이전에 설명되었습니다18.
</li>
</ol>3. 미세 유체 챔버를 조립하고 시투 시편 홀더를 로드
<ol><li>바이러스 성 시료를 포함하는 젖은 E 칩을 미세 유체 표본 홀더의 끝에 적재합니다. 제2 플랫 E-칩을 1분 동안 발광한 다음 스페이서 칩 위에 적재합니다(그림2, 패널 1-5).</li>
	<li>대안적으로, 생물학적 거대분자의 대비를 높이기 위해 중금속얼룩(예를 들어 0.2% uranyl formate)은 습식 시편에 제2 E칩을 배치하기 전에 습식 시편에 첨가될 수 있다. 그러나 시편을 함유한 E-칩은 대비 시약을 추가하기 전에 밀리-Q 물로 세척해야 합니다.</li>
	<li>전체 어셈블리를 함께 샌드위치하여 3개의 황동나사(그림 2,패널 6-8)로 홀더 내에서 기계적으로 제자리에 고정된 밀봉된 인클로저를 형성합니다.</li>
	<li>조립 후 홀더의 끝은 TEM 내부에 홀더를 배치하기 전에 터보 펌핑 건조 펌핑 스테이션을 사용하여10-6 Torr로 펌핑됩니다.</li>
</ol>4. 전송 전자 현미경을 사용하여 액체에서 이미징
<ol><li>LaB6 필라멘트가 장착된 전송 전자 현미경(FEI Company)에 시투 시편 홀더를 적재하고 120kV에서 작동합니다.</li>
	<li>TEM 필라멘트를 켜고 보블러 기능을 사용하여 시편과 관련하여 현미경 단계의 유중심 높이를 조정하여 컬럼에서 -15°에서 +15°로 샘플을 기울이고 있습니다. 이 절차는 액체 챔버의 적절한 두께를 설명하기 위해 z 방향으로 스테이지를 조정합니다. 또한 이 단계는 이미지를 기록할 때 정확한 배율이 사용되도록 합니다.</li>
	<li>먼저 미세 유체 챔버의 가장자리와 모서리 영역에 이미지를 기록합니다. 이러한 영역에는 일반적으로 가장 얇은 솔루션이 포함됩니다. CCD 카메라를 사용하여 저용량 조건(1-3 전자/Å2)에서표본의 이미지를 기록합니다. 명목 배율을 6,000X - 30,000X로 사용하십시오.</li>
	<li>유체 챔버의 가장자리에 초점을 맞추어 적절한 디포커스 값을 결정합니다. -1.5 μm값을 사용하여 30,000배율로 이미지를 기록합니다. 두꺼운 용액이 발생하거나 시편 제조에 조영제가 사용되지 않는 경우 -2 ~ -4 μm 범위에서 더 높은 디포커스 값을 사용합니다.</li>
	<li>용액이 실험 전반에 걸쳐 미세 유체 챔버에 포함되도록 하기 위해 장치 내의 액체에 기포가 형성될 때까지 전자 빔에 초점을 맞춥니다.</li>
</ol>

<ol>
	<li>Zhou, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+atomic+resolution+structural+determination+by+single-particle+cryo-electron+microscopy.">Towards atomic resolution structural determination by single-particle cryo-electron microscopy.</a> Curr. Opin. Struct. Biol. 18, 218-228 (2008).</li><li>Wolf, M., Garcea, R. L., Grigorieff, N., Harrison, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subunit+interactions+in+bovine+papillomavirus.">Subunit interactions in bovine papillomavirus.</a> Proc. Natl. Acad. Sci. U.S.A. 107, 6298-6303 (2010).</li><li>Dubochet, 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=Cryo-electron+microscopy+of+vitrified+specimens.">Cryo-electron microscopy of vitrified specimens.</a> Q. Rev. Biophys. 21, 129-228 (1988).</li><li>Unwin, P. N., Henderson, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+structure+determination+by+electron+microscopy+of+unstained+crystalline+specimens.">Molecular structure determination by electron microscopy of unstained crystalline specimens.</a> J. Mol. Biol. 94, 425-440 (1975).</li><li>Ohi, M., Li, Y., Cheng, Y., Walz, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Negative Staining and Image Classification - Powerful Tools in Modern Electron Microscopy. Biol. Proced. Online. 6, 23-34 (2004).</li><li>Adrian, M., Dubochet, J., Fuller, S. D., Harris, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryo-negative+staining.">Cryo-negative staining.</a> Micron. 29, 145-160 (1998).</li><li>Parsons, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+of+wet+specimens+in+electron+microscopy.+Improved+environmental+chambers+make+it+possible+to+examine+wet+specimens+easily.">Structure of wet specimens in electron microscopy. Improved environmental chambers make it possible to examine wet specimens easily.</a> Science. 186, 407-414 (1974).</li><li>Parsons, D. F., Matricardi, V. R., Moretz, R. C., Turner, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+microscopy+and+diffraction+of+wet+unstained+and+unfixed+biological+objects.">Electron microscopy and diffraction of wet unstained and unfixed biological objects.</a> Adv. Biol. Med. Phys. 15, 161-270 (1974).</li><li>Hui, S. W., Parsons, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+diffraction+of+wet+biological+membranes.">Electron diffraction of wet biological membranes.</a> Science. 184, 77-78 (1974).</li><li>Hui, S. W., Parsons, D. F., Cowden, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+diffraction+of+wet+phospholipid+bilayers.">Electron diffraction of wet phospholipid bilayers.</a> Proc. Natl. Acad. Sci. U.S.A. 71, 5068-5072 (1974).</li><li>Ring, E. A., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+system+for+transmission+electron+microscopy.">Microfluidic system for transmission electron microscopy.</a> Microsc. Microanal. 16, 622-629 (2010).</li><li>Dukes, M. J., Ramachandra, R., Baudoin, J. P., Gray Jerome, W., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+locations+of+gold-labeled+proteins+in+a+whole+mount+eukaryotic+cell+obtained+with+3nm+precision+using+aberration-corrected+scanning+transmission+electron+microscopy.">Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3nm precision using aberration-corrected scanning transmission electron microscopy.</a> J. Struct. Biol. 174, 552-562 (2011).</li><li>Yuk, J. M., 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=High-resolution+EM+of+colloidal+nanocrystal+growth+using+graphene+liquid+cells.">High-resolution EM of colloidal nanocrystal growth using graphene liquid cells.</a> Science. 336, 61-64 (2012).</li><li>Peckys, D. B., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+gold+nanoparticle+uptake+in+live+cells+with+liquid+scanning+transmission+electron+microscopy.">Visualizing gold nanoparticle uptake in live cells with liquid scanning transmission electron microscopy.</a> Nano Lett. 11, 1733-1738 (2011).</li><li>Klein, K. L., Anderson, I. M., de Jonge, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transmission+electron+microscopy+with+a+liquid+flow+cell.">Transmission electron microscopy with a liquid flow cell.</a> J. Microsc. 242, 117-123 (2011).</li><li>Degen, K., Dukes, M., Tanner, J. R., Kelly, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+affinity+capture+devices-a+nanoscale+purification+platform+for+biological+in+situ+transmission+electron+microscopy.">The development of affinity capture devices-a nanoscale purification platform for biological in situ transmission electron microscopy.</a> Rsc. Adv. 2, 2408-2412 (2012).</li><li>Gilmore, B. L., 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=Visualizing+viral+assemblies+in+a+nanoscale+biosphere.">Visualizing viral assemblies in a nanoscale biosphere.</a> Lab Chip. 13, 216-219 (2013).</li><li>Bican, P., Cohen, J., Charpilienne, A., Scherrer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+bovine+rotavirus+cores.">Purification and characterization of bovine rotavirus cores.</a> J. Virol. 43, 1113-1117 (1982).</li><li>Frank, 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=SPIDER+and+WEB:+processing+and+visualization+of+images+in+3D+electron+microscopy+and+related+fields.">SPIDER and WEB: processing and visualization of images in 3D electron microscopy and related fields.</a> J. Struct. Biol. 116, 190-199 (1996).</li><li>Zhang, 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=Near-atomic+resolution+using+electron+cryomicroscopy+and+single-particle+reconstruction.">Near-atomic resolution using electron cryomicroscopy and single-particle reconstruction.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 1867-1872 (2008).</li><li>Scheres, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Bayesian+view+on+cryo-EM+structure+determination.">A Bayesian view on cryo-EM structure determination.</a> J. Mol. Biol. 415, 406-418 (2012).</li><li>Kelly, D. F., Abeyrathne, P. D., Dukovski, D., Walz, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Affinity+Grid:+a+pre-fabricated+EM+grid+for+monolayer+purification.">The Affinity Grid: a pre-fabricated EM grid for monolayer purification.</a> J. Mol. Biol. 382, 423-433 (2008).</li></ol>

저자, 매들린 J. 듀크스, 프로토 칩스의 직원입니다, Inc.

제시된 작업에서, 우리는 마이크로 유체 플랫폼에 밧줄 로타 바이러스 DLP에 친화성 캡처 접근 방식을 채택했다. 이것은 액체 미세 환경에서 매크로 분자 복합체의 시상 화상 진찰에서 허용했습니다. 포획 접근법은 다른 미세 유체 이미징 기술과 관련하여 중요한데, 이는 액체에서 이미지를 기록하는 동안 발생하는 큰 확산 문제를 부정하기 위해 이미징 창에 생물학적 표본을 국...

<a href="https://app.jove.com/t/6605">This corrects</a> the article <a href="https://dx.doi.org/10.3791/50936">10.3791/50936</a>

An erratum was issued for:&#160;<a href="https://www.jove.com/t/50936">In situ TEM of Biological Assemblies in Liquid</a>. The Representative Results and References sections were&#160;updated.

Erratum: In situ TEM of Biological Assemblies in Liquid

생물학자와 엔지니어의 공통된 목표는 분자 기계의 내부 작동을 이해하는 것입니다. 전송 전자 현미경 (TEM)은 거의 원자 해상도1-2에서이러한 복잡한 세부 사항을 시각화하기에 이상적인 도구입니다. TEM의 높은 진공 시스템을 유지하기 위해, 생물학적 샘플은 전형적으로 유리체3,설탕4,중금속 염5,또는 그일부조합6의 박막에 내장되어 있다. 따라서 임베디드 표본의 이미지는 동적 프로세스의 제한된 스냅샷만 나타낼 수 있습니다.
환경 액체 챔버에서 수화 된 생물학적 표본을 유지하기 위한 초기 시도는 파슨스와 동료들이 차동 펌핑 단계를 사용하여 수행되었습니다. 스테인드 카탈라제 결정의 전자 회절 패턴은7-8수화 상태에서 3Å의 해상도로 성공적으로 기록되었다. 또한, 위상 분리지질 도메인은 인간 적혈구9-10의수화 막에서 검사될 수 있었다. 그러나, 액체를 확산시키고 전자빔과의 간섭으로 인한 움직임은, 생물학적 표본을 이용한 심한 분해능 손실 및 추가 실험이 최근까지 시도되지 않았다.
새로 개발된 미세유체 표본 홀더는 반도체 마이크로칩을 활용하여 마이크로 스케일환경챔버를 형성하는 것으로 소개되었습니다. 이러한 장치는 TEM 컬럼11-12에위치하는 동안 액체로 샘플을 유지할 수 있습니다. TEM 이미징의 이러한 기술적 돌파구는 연구자들이 분자 수준13에서처음으로 진보적인 사건을 볼 수 있게 해 주어 왔다. 우리는 실험이 이제 EM 컬럼14-15를"내부"수행 할 수 있으므로"시투 분자 현미경 검사법에서"로이 새로운 양식도를 지칭한다. 이 방법의 전반적인 목표는 나노미터 해상도에서 그들의 동적 행동을 관찰하기 위하여 액체에 있는 생물학 어셈블리를 심상하는 것입니다. 개발 된 기술의 근거는 실시간 관찰을 기록하고 용액에서 생물학적 기계의 새로운 특성을 검사하는 것입니다. 이 방법론은 세포 및 분자 생물학12-16에서더 넓은 목적을 위해 TEM의 사용을 확장합니다.
현재 비디오 문서에서는 시판되는 미세 유체 표본 홀더를 조립하고 사용하는 포괄적인 프로토콜을 제시합니다. 이 전문 홀더는 통합 스페이서로 생성된 실리콘 트랜티드 마이크로칩을 사용하여 미세량의 용액을 둘러싸는 액체 챔버를 형성합니다. 얇고 투명한 창문은 이미징 목적을 위해 마이크로칩에 새겨져있다(12). 우리는 TEM을 사용하여 액체에 있는 simian rotavirus 이중 층 입자 (DlPs)를 검사하기 위하여 미세 유체 홀더의 적당한 사용을 보여줍니다. DP와 같은 생물학적 어셈블리가 이미징 하는 동안 먼 거리에서 빠르게 확산되지 않도록 하기 위해, 우리는 미세 유체챔버(16)의표면에 그들을 묶기 위해 선호도 캡처 접근법을 채택한다. 이 분자 포획 단계는 다운스트림 처리 루틴에 사용될 이미지의 수집을 허용하기 때문에 액체에서 생물학적 표본을 이미징하기위한 대체 기술에 비해 주요 이점이 있습니다. 미세 유체 이미징과 함께 사용되는 이 캡처 단계는 당사의절차(17)에고유합니다. TEM 또는 미세 유체 이미징 챔버를 사용하여 구조 생물학 응용 프로그램을 사용하는 독자는 분자 수준에서 동적 관찰이 최종 목표일 때 친화성 캡처 기술의 사용을 고려할 수 있습니다.

<table border="0" cellpadding="0" cellspacing="0" width="832">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="43">
			<td height="43" style="height:43px;width:237px;">E-chips, spacer chip</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;">EPB-52TBD</td>
			<td style="width:167px;">400 &#956;m x 50 &#956;m window</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:237px;">E-chip, top chip</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;">EPT-45W</td>
			<td style="width:167px;">400 &#956;m x 50 &#956;m window</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Ni-NTA lipid</td>
			<td style="width:183px;">Avanti Polar Lipids</td>
			<td style="width:245px;">790404P</td>
			<td style="width:167px;">Powder form</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">DLPC (12:0) lipid</td>
			<td style="width:183px;">Avanti Polar Lipids</td>
			<td style="width:245px;">850335P</td>
			<td style="width:167px;">Powder form</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Volumetric flasks&#160;</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">20-812A; 20-812C</td>
			<td style="width:167px;">1 ml; 5 ml&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Hamilton Syringes</td>
			<td style="width:183px;">Hamilton Co.</td>
			<td style="width:245px;">80300, 80400</td>
			<td style="width:167px;">1-10 &#956;l; 1-25 &#956;l</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Whatman #1 filter paper</td>
			<td style="width:183px;">Whatman</td>
			<td style="width:245px;">1001 090</td>
			<td style="width:167px;">100 pieces, 90 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass Petri dishes</td>
			<td style="width:183px;">Corning&#160;</td>
			<td style="width:245px;">70165-101</td>
			<td style="width:167px;">100 mm x 15 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass Pasteur pipettes</td>
			<td style="width:183px;">VWR</td>
			<td style="width:245px;">14673-010</td>
			<td style="width:167px;">14673-010</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Glass culture tubes</td>
			<td style="width:183px;">VWR</td>
			<td style="width:245px;">47729-566</td>
			<td style="width:167px;">6 mm x 50 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Acetone</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">&#160;A11-1</td>
			<td style="width:167px;">1 L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Methanol</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">&#160;A412-1</td>
			<td style="width:167px;">1 L</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">Chloroform&#160;</td>
			<td style="width:183px;">Electron Microcopy Sciences</td>
			<td style="width:245px;">12550</td>
			<td style="width:167px;">100 ml&#160;</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">His-tagged Protein A</td>
			<td style="width:183px;">Abcam, Inc.</td>
			<td style="width:245px;">ab52953</td>
			<td style="width:167px;">10 mg</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">Milli-Q water system</td>
			<td style="width:183px;">EMD Millipore Corp.</td>
			<td style="width:245px;">Z00QSV001</td>
			<td style="width:167px;">Ultrapure Water</td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:237px;">HEPES</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;">BP310-500</td>
			<td style="width:167px;">500 g</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Equipment&#160;</td>
			<td style="width:183px;"></td>
			<td style="width:245px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Poseidon In situ specimen holder</td>
			<td style="width:183px;">Protochips, Inc.</td>
			<td style="width:245px;"></td>
			<td>&#160;FEI compatible</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">FEI Spirit BioTwin TEM</td>
			<td style="width:183px;">FEI Co.</td>
			<td style="width:245px;"></td>
			<td>120 kV</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:237px;">Eagle 2k HS CCD camera</td>
			<td style="width:183px;">FEI Co.</td>
			<td style="width:245px;"></td>
			<td>10&#160;&#197;/pixel sampling at 30,000X</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:237px;">Gatan 655 Dry pump station</td>
			<td style="width:183px;">Gatan, Inc.</td>
			<td style="width:245px;"></td>
			<td>Pump holder tip to 10-6&#160;range</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:237px;">PELCO easiGlow, glow discharge unit</td>
			<td style="width:183px;">Ted Pella, Inc.</td>
			<td style="width:245px;"></td>
			<td>&#160;Negative polarity mode</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:237px;">Isotemp heated stir plate</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:245px;"></td>
			<td>Heat to 150 &#186;C for 1.5 hr</td>
		</tr>
	</tbody>
</table>

in situ tem of biological assemblies in liquid

연구원은 정기적으로 전염 전자 현미경 (TEM)을 사용하여 생물학적 개체를 검사하고 새로운 물질을 평가합니다. 여기서는 액체 환경에서 이러한 계측기-바이러스 성 어셈블리를 볼 수 있는 추가 응용 프로그램에 대해 설명합니다. 생물학적 구조를 시각화하는 이 흥미롭고 새로운 방법은 최근에 개발된 미세 유체 기반 표본 홀더를 활용합니다. 비디오 기사에서는 미세 유체 홀더를 조립하고 사용하여 TEM 내에서 액체 표본을 이미지화하는 방법을 보여 줍니다. 특히, 우리는 우리의 모델 시스템으로 시미안 로타 바이러스 이중 층 입자 (DlP)를 사용합니다. 우리는 또한 보기 창에 DLP를 묶는 친화성 생물막으로 액체 챔버의 표면을 코팅하는 단계를 설명합니다. 이렇게 하면 3D 구조 결정에 적합한 방식으로 어셈블리를 이미지할 수 있습니다. 따라서, 우리는 네이티브 액체 환경에서 서브 바이러스 입자의 첫 번째 엿볼을 제시한다.

광분 방출된 E칩을 이용한 액체의 DlP의 대표적인이미지(그림 3A)는선호도 캡처 장치(그림3B)에농축된 DlP에 비해 확산으로 인한 특정 보기 영역에서 더 적은 DP를 보여준다. 이미징 챔버에 우라알 수감자를 첨가하면 시편의 대비를 향상시키고 따라서 용액에서 개별 DlP의가시성(도 3C,상단 패널). 더 나은 콘트라스트는 이전에 설명된17과같이 입자평...

Watch this Scientific Journal Video about In situ TEM of Biological Assemblies in Liquid at JoVE.com

In situ TEM of Biological Assemblies in Liquid

여기서는 투과 전자 현미경을 이용하여 나노미터 해상도로 액체에 바이러스 성 복합체를 이미지화하는 절차를 설명합니다.

시투에서 액체에 있는 생물학 어셈블리의 TEM

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an ...

in-situ-tem-of-biological-assemblies-in-liquid

Research

JoVE Journal

Bioengineering

In situ TEM of Biological Assemblies in Liquid

10.0K 조회수.  Protochips, Inc.. 여기서는 투과 전자 현미경을 이용하여 나노미터 해상도로 액체에 바이러스 성 복합체를 이미지화하는 절차를 설명합니다.

비디오: In situ TEM of Biological Assemblies in Liquid

Multiparametric Optical Mapping of the Langendorff-perfused Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not have been accomplished by other approaches1. With the use of the calcium- and voltage-sensitive dyes, optical mapping allows measurement of transmembrane action potentials and calcium transients with high spatial resolution without the physical contact with the tissue. This makes measurements of the cardiac electrical activity possible under many conditions where the use of electrodes is inconvenient or impossible1. For example, optical recordings provide accurate morphological changes of membrane potential during and immediately after stimulation and defibrillation, while conventional electrode techniques suffer from stimulus-induced artifacts during and after stimuli due to electrode polarization1. 
The Langendorff-perfused rabbit heart is one of the most studied models of human heart physiology and pathophysiology. Many types of arrhythmias observed clinically could be recapitulated in the rabbit heart model. It was shown that wave patterns in the rabbit heart during ventricular arrhythmias, determined by effective size of the heart and the wavelength of reentry, are very similar to that in the human heart2. It was also shown that critical aspects of excitation-contraction (EC) coupling in rabbit myocardium, such as the relative contribution of sarcoplasmic reticulum (SR), is very similar to human EC coupling3. Here we present the basic procedures of optical mapping experiments in Langendorff-perfused rabbit hearts, including the Langendorff perfusion system setup, the optical mapping systems setup, the isolation and cannulation of the heart, perfusion and dye-staining of the heart, excitation-contraction uncoupling, and collection of optical signals. These methods could be also applied to the heart from species other than rabbit with adjustments to flow rates, optics, solutions, etc.
Two optical mapping systems are described. The panoramic mapping system is used to map the entire epicardium of the rabbit heart4-7. This system provides a global view of the evolution of reentrant circuits during arrhythmogenesis and defibrillation, and has been used to study the mechanisms of arrhythmias and antiarrhythmia therapy8,9. The dual mapping system is used to map the action potential (AP) and calcium transient (CaT) simultaneously from the same field of view10-13. This approach has enhanced our understanding of the important role of calcium in the electrical alternans and the induction of arrhythmia14-16.

This article describes the basic procedures for conducting optical mapping experiments in the Langendorff-perfused rabbit heart using the panoramic imaging system, and the dual (voltage and calcium) imaging modality.

Langendorff - perfused 토끼 하트의 Multiparametric 광 매핑

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not ...

연구

생체공학

Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products.
While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites13.
Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids.

This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).

타겟 안정 동위 원소 희석 액체 크로마 토그래피 - 질량 분광법 분석을위한 세포 지질 추출

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including ...

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

매개 변수화 이완기 충전 형식주의를 통해 Transmitral 흐름의 운동 학적 모델링 기반의 분석에 의하여 세계적인 이완기 기능의 정량화

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper and cystine, with either copper nanoparticles (CNPs) or copper sulfate contributing the metallic component. Synthesis is carried out in liquid under biological conditions (37 &#176;C) and the self-assembled composites form after 24 hr. Once formed, these composites are highly stable in both liquid media and in a dried form. The composites scale from the nano- to micro- range in length, and from a few microns to 25 nm in diameter. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) demonstrated that sulfur was present in the NP-derived linear structures, while it was absent from the starting CNP material, thus confirming cystine as the source of sulfur in the final nanocomposites. During synthesis of these linear nano- and micro-composites, a diverse range of lengths of structures is formed in the synthesis vessel. Sonication of the liquid mixture after synthesis was demonstrated to assist in controlling average size of the structures by diminishing the average length with increased time of sonication. Since the formed structures are highly stable, do not agglomerate, and are formed in liquid phase, centrifugation may also be used to assist in concentrating and segregating formed composites.

Here we present a protocol to synthesize novel, high-aspect ratio biocomposites under biological conditions and in liquid media. The biocomposites scale from nanometers to micrometers in diameter and length, respectively. Copper nanoparticles (CNPs) and copper sulfate combined with cystine are the key components for the synthesis.

생물 액체 배지에서 확장 성, 금속 높은 가로 세로 비율 나노 복합 재료의 생성

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper ...

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances (EPS). The EPS serves as a physical and protective scaffold that houses the bacterial cells and consists of a variety of materials that includes proteins, exopolysaccharides and DNA. The composition of the EPS may change, which remodels the mechanic properties of the biofilm to further develop or support alternative biofilm structures, such as streamers, as a response to environmental cues. Despite this, there are little quantitative descriptions on how EPS components contribute to the mechanical properties and function of biofilms. Rheology, the study of the flow of matter, is of particular relevance to biofilms as many biofilms grow in flow conditions and are constantly exposed to shear stress. It also provides measurement and insight on the spreading of the biofilm on a surface. Here, particle-tracking microrheology is used to examine the viscoelasticity and effective crosslinking roles of different matrix components in various parts of the biofilm during development. This approach allows researchers to measure mechanic properties of biofilms at the micro-scale, which might provide useful information for controlling and engineering biofilms.

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Particle-tracking microrheology investigates the viscoelasticity of materials. Here, the technique is used to determine the viscoelasticity, creep compliance and effective crosslinking roles of different matrix components of a bacterial biofilm. The matrix consists of polymeric substances secreted by the bacteria and its components determine biofilm structure and mechanical properties.

입자 추적 Microrheology에 의한 바이오 필름의 기계적 성질의 제자리 매핑에서

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances ...

Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system.

We present a facile method to fabricate a biodegradable gelatin-based drug release platform that is magneto-thermally responsive. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and poly(N-isopropylacrylamide-co-acrylamide) within a spherical gelatin micro-network crosslinked by genipin, in conjunction with an alternating magnetic field application system.

제어 약물 릴리스에 대한 자기장 응답 하이브리드 젤라틴 마이크로 겔을 교류

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of ...

A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are quickly moving into the operating room. Here, we present a new approach that utilizes a technique not yet explored for intraoperative imaging: chemiluminescent imaging. This method employs a ruthenium-based chemiluminescent reporter along with a custom-built nebulizing system to produce ex vivo or in vivo images with high signal-to-noise ratios. The ruthenium-based reporter produces light following exposure to an aqueous oxidizing solution and re-reduction within the surrounding tissue. This method has allowed us to detect reporter concentrations as low as 6.9 pmol/cm2. In this work, we present a visual guide to our proof-of-concept in vivo studies involving subdermal and intravenous injections in mice. The results suggest that this technology is a promising candidate for further preclinical research and might ultimately become a useful tool in the operating room.

This protocol describes a new intraoperative imaging technique that uses a ruthenium complex as a source of chemiluminescent light emission, thereby producing high signal-to-noise ratios during in vivo imaging. Intraoperative imaging is an expanding field that could revolutionize the way that surgical procedures are performed.

생물학적 설정에서 생성 및 관측 화학 발광위한 새로운 기술

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are ...

Automated Robotic Liquid Handling Assembly of Modular DNA Devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; represented by &#34;devices&#34; created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction.
Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols.
The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation.

Here, an automated workflow to perform modular DNA &#34;device&#34; assembly using a modular cloning DNA assembly method on liquid-handling robots is presented. The protocol uses an intuitive software tool for generating liquid handler picklists for combinatorial DNA device library generation, which we demonstrate using two liquid handling platforms.

모듈형 DNA 장치 조립 로봇 액체 처리 자동화

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

<em&gt; 체외</em쥐의 추간판의&gt; 장기 문화 모델

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

3D 공간 세포 배양을위한 세포 발판으로 생체 적합성 액정 엘라스토머 거품의 합성

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...