This research was supported in part by a National Research Service Award (T32GM07616) from the National Institute of General Medical Sciences.

1. 실험 설정 및 샘플 준비 <ol><li> 리소그래피를 사용하여 에칭하고, 이전에 설명 된 바와 같이 6 과정을 용융 microtoroids를 제작. 일반적으로 80 내지 100 ㎛의 주요 직경, 2 ㎛의 작은 직경을 갖는 실리콘 웨이퍼 (칩)의 상단에 microtoroids를 제작. </li><li> 대략의 섬유 스풀에서 단일 모드 광섬유 (125 μm의 클래딩, 4.3 μm의 모드 필드 직경)의 미터 긴장을 풀고. </li><li> 광섬유의 풀린 부분의 중간에, 와이어 스트리퍼를 사용하여 광 화이버의 주위에 폴리머 코팅재의 작은 세그먼트 (2.5 cm)를 스트립. 주 :이 microtoroid 순간적으로 커플 광에 사용되는 광섬유의 부분이다. </li><li> 이소프로판올 알코올과 무료로 닦아 보풀 제거 섬유를 청소합니다. </li><li> 자기 클램프로 만든 섬유 홀더를 사용하는 대신에 섬유의이 부분을 잡으십시오. </li><li> meltin으로 ~ 500 nm의 얇은 스트립 섬유g 및 수소 토치가 60㎛ / 분에서 서로 반대 방향으로 움직이는 두 개의 스텝퍼 모터를 사용하여 당기는. ~ 10mm 높이 있어야 화염의 상부 내부에 광섬유를 위치. 광섬유를 통해 전송이 (오프 섬유 점멸로부터 측 방향으로 산란되는 광을 보면서)이나 오실로스코프에 연결된 포토 다이오드에 섬유를 연결하여 시각적으로 감시 할 수있는 요동 정지시 섬유 당기는 중지 . </li><li> 광섬유의 한쪽 끝을 절단 및 베어 섬유 어댑터에 삽입합니다. 수광부의 입력에 섬유의 끝을 놓습니다. </li><li> 섬유 커플 광섬유 결합기를 이용하여 레이저 광 스풀의 타단. </li><li> 에폭시 또는 양면 테이프를 사용하여 샘​​플 홀더의 상단에있는 microtoroid 칩 (스테인레스 스틸, 37.8 mm X 6.4 mm X 3.2 mm)를 놓습니다. </li><li> (3 축 나노 포지셔닝 포함하는 위치 결정 스테이지의 상부에 샘플 홀더를 마운트 N3 축 마이크로 미터 위에 anocube) 단계 (장치 목록 참조). 진동을 최소화하기 위해 공압 고립 된 광학 테이블에 모든 실험을 수행합니다. </li><li> 조대 위치 3 축 마이크로 미터를 사용하여 샘​​플 칩. </li><li> 나노 포지셔너를 사용하여 광섬유에 microtoroid 함유 칩과 평행을 맞 춥니 다. 참고 : 입력 광 (~ 633 ㎚)의 한 파장의 거리에 microtoroid을 맞 춥니 다. 이 프로세스의 시각화를위한 두 개의 촬상 컬럼 사용 상단과 칩의 측면 상에 위치 (대물 렌즈 및 카메라를 가진 튜브를 장비 목록 참조). </li><li> 인라인 편광 제어기를 사용하여 광섬유를 통해 지향 레이저 광의 편광을 최적화하는 편광을 조정 노브 (장치 목록 참조). 주 : 광섬유의 전송에서 측정 된 딥 좁은 나타날 때 최적의 편광이 달성된다. 오실로스코프 (자세한 내용은 단계 2.2 참조)이 수영을 관찰한다. </li><li> 구축스페이서로서 유리 현미경 슬라이드를 사용하여 샘​​플 스테이지 위에 유리 커버 슬립을 epoxying 의해 샘플 챔버. 참고 : 전체 설치를 포함하는 플렉시 유리 인클로저는 공기 흐름을 최소화하는 데 유용 할 수 있습니다. 작은 개구는 튜브를 사용하여 펌핑 할 수있는 솔루션을 수 있도록 남아 있어야합니다. </li><li> 열적 RT 수조 (~ 500 ml)에 1 시간 동안 ≥ 입자 현탁액 또는 단일 분자 수용액 평형. 참고 : 시료는 제조 업체, 예를 들어, PBS 또는 HEPES에서 지정한 관련 버퍼를 사용하여 마이크로 원심 튜브에 원하는 농도로 희석한다. 어떠한 바인딩 이벤트가 검출되지 않은 경우, 버퍼의 염 농도를 증가시킨다. </li><li> ~ 2 초 동안 솔루션 (1 ml)을 간략하게 포함 소용돌이 입자. </li><li> 1 mL의 샘플에서 챔버 내로 입자 함유 용액을 주입 / 1ml를 주사기 펌프를 사용하여 민. </li><li> 샘플 챔버가 작성되면, 주사기 펌프의 전원을 끄십시오. </li><li> 기록 데이터를 최소화하기 전에 30 초를 기다립니다측정에 영향을 미칠 수있는 유체의 흐름으로 인한 기계적인 진동의 영향. </li></ol> 2. 주파수 잠금 <ol><li> 커플 링은 유체의 주입으로 인해 방해되기 때문에, 나노 위치로 샘플 홀더를 이동시킴으로써 광섬유에 토 로이드 - 커플 재. </li><li> 다양한 파장 통해 컴퓨터 제어 입력을 레이저 스캐닝하여 microtoroid의 공진 파장을 찾아. 레이저의 파장을 조절하는 레이저 컨트롤러 내의 압전 소자에 삼각파 전압 신호를 전송하여이 단계를 수행한다. 이 파장에서 물에 빛의 낮은 흡수가로 가시 광선 (2.5 nm의 ± 635 나노 미터)를 사용하여 실험을 수행합니다. </li><li> 자동 평형 수광부로 광섬유의 출력을 연결하여 광섬유를 통해 광 투과율을 측정한다. BNC 케이블을 사용하여 오실로스코프에 수광부의 출력을 연결합니다. O 관찰n은 오실로스코프는 microtoroid의 공진 파장에서, 광섬유를 통해 전송 방울있다. </li><li> 케이블을 통해 피드백 컨트롤러 (장비 목록 참조) 고정 주파수의 주요 입력 수광부의 출력을 연결합니다. </li><li> 2 kHz의 디더 주파수와 19 FM의 파장 진동의 진폭과 잠금 최고 수준의 피크를 사용하여 자동 잠금 모드에서 주파수 잠금 피드백 제어를 실행합니다. 경험적으로 지글러 - 니콜스 튜닝 규칙 (14)을 사용하여 소프트웨어 창의 비례 적분 미분 설정을 설정한다. 참고 :이 값은 모든 실험의 시작 부분에 한 번 설정 만하면됩니다. </li><li> microtoroid의 공진 파장 레이저의 파장을 자동 - 잠금. 샘플 챔버를 충전 한 후이 단계를 수행합니다. 주 : 파장 변화가 너무 큰 경우, 피드백 제어기는 잠금을 잃게 자동 공진 파장의 위치를​​ 찾기 위해 스캔 모드로 전환. 이 OC파장에 대한 CURS 약 1 선폭 (여기 조사 모든 시스템에 대해 적어도 600 FM)보다 큰 이동합니다. </li><li> 24 비트 데이터 수집 카드를 사용하여 20 kHz에서 피드백 제어기의 출력을 기록한다. 데이터 수집 소프트웨어를 통해 텍스트 파일로 데이터를 내보낼. </li></ol> 3. 데이터 처리 및 분석 <ol><li> 푸리에 MATLAB에서 데이터를 변환. </li><li> 낮은 2 kHz에서의 부과 디더 주파수를 제거하기 위해 1 kHz에서 컷오프와 &quot;벽돌 벽&quot;필터를 사용하여 데이터를 전달 (보충 코드 스크린 샷 1 파일 참조). </li><li> 계산적 노치는 16 Hz의 윈도우 크기를 사용하여 데이터를 필터링. 참고 :이이 경우에, 소음의 알려진 원인을 제거하기위한 것입니다, 60 Hz의 전자 라인 노이즈 및 고조파 (레이저 드라이버에서 오는)뿐만 아니라 100 Hz에서의 고조파 (보충 코드 스크린 샷 1 파일 참조). </li><li> 역 푸리에 변환은 시간 도메인으로 데이터를 다시 변환. </li><li> 메디안 필터 창을 이용하여 상기 데이터1,001 샘플의 크기 (보충 코드 스크린 샷 2 파일 참조). </li><li> Kerssemakers 등. (15)의 스텝 찾는 알고리즘을 사용하여 공진 파장의 단계 변화를 찾습니다. </li><li> 각 바인딩 단계의 진폭의 히스토그램을 생성합니다. </li><li> 식을 사용하여 입자 크기를 계산한다. (1) (토론 참조). </li></ol>

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The authors declare that they have no competing financial interests.

입자가 결합 된 바와 같이, 환형 상승의 공진 파장 (λ). 입자가 바인딩 해제하면, 공진 파장은 대응 (스텝 - 다운 이벤트)를 감소시킨다. 입자 직경 (d)는 각각의 파장 단계의 진폭 히스토그램을 통해 결정될 수있다. 각 파장 단계의 높이가 결합 입자의 크기 변화로 인해 입자가 결합 microtoroid의 위치로 인해 변한다. 입자는 전기장 (E 0 맥스)이 최대가 microtoroid의 적?...

단일 분자 검출 실험은 질병의 조기 진단을위한 바이오 센서에 사용되는 분석 물의 양을 감소시키는 데 유용하며, 분자 (3)의 기본 특성을 조사하기위한. 이러한 실험은 일반적으로 라벨 그러나, 라벨은 항상 이벤트가 검토되고 교란 수, 비용 증가, 특정 단백질을 얻을 수없고, 특히 현장 실험 또는 포인트 외 실시간 들면 불편할 수있다하여 수행 의료 진단. 라벨없는 바이오 센서에 대한 현재 금 표준 그러나 상업적 표면 플라즈몬 공명 시스템은 전형적 nm 인 검출 순서에 전형적인 하한을 가지고, 표면 플라즈몬 공명 (4)이다. 최근, 광 공진기는 라벨이없는 단일 분자 biodetection 5 유망 기술로 등장했다. 장기 (NS)에 기초하여 광 공진기 일 -6,7-의 광 가둠. 빛은 순간적이다일반적으로, 광섬유를 통해 이러한 장치에 연결된다. 섬유 거치지 광의 파장 공진기의 공진 파장과 일치 할 때, 효율적으로 공진기에 커플 빛. 이 결합 된 광은 완전히 내부 공진기의 둘레 근방에 소 산장을 발생 공진기의 공동 내에 반영한다. 입자는 공진기, 입자 (8)의 체적에 비례하여 변화 공진기의 공진 파장 산장 인드에 진입. 검출 능력의 관점에서, 미세 공진기 이전 단일에게 인플루엔자 바이러스 입자 (100 ㎚) 9,10 검출하는데 사용되어왔다. 최근 plasmonically 향상된 미세 광학 공진기 그러나이 접근법은 드 0.3 μm의 (2)에 입자 포획 영역을 제한하고, 분자 (11) 및 8 량체 올리고 12 알부민 단일 소 혈청을 검출하는데 사용되어왔다바이스. 큰 캡처 영역 바이오 센서는 입자 검출의 가능성을 최대화 이상적이다. 큰 (&gt; 100 μm의 2) 캡쳐 영역과 현재 솔루션 기반의 라벨없는 바이오 센싱 기술은 폴리스티렌 입자를 ≥ 25 nm의 검출에 한정되어있다. 우리는 용액 중의 분자의 단일 시간 - 분해 검출 할 수있는 에바 네 슨트 광 위스퍼 링 공진기 (FLOWER) (13) (도 1)을 잠그기 주파수라고도 광 공진기 기술 기반의 라벨없는 바이오 센싱 시스템을 개발 하였다. FLOWER 주파수 로크 피드백 제어, 평형 검출 한 단일 단백질 분자로 내려 작은 입자를 검출하는 필터링 연산과 결합 microtoroid 광학 공진기의 길이 광자 수명을 이용한다. 주파수 록의 이용은 스위프 또는 레이저 파장을 스캐닝 할 필요없이, 입자 결합으로 시스템이 항상 microtoroid의 이동 공명을 추적 할 수 있도록큰 범위. 꽃의 원리 플라즈몬 강화를 포함하는 다른 기법의 검출 능력을 향상시키기 위해 사용될 수있다. 다음 것에서, FLOWER를 행하는 절차를 설명한다.

<table border="0" cellpadding="0" cellspacing="0" width="396">
	<tbody>
		<tr height="20" style="height:15.0pt">
			<td class="xl63" height="20" style="height:15.0pt;width:99pt" width="132">Tunable diode laser</td>
			<td class="xl63" style="width:99pt" width="132">Newport</td>
			<td class="xl63" style="width:99pt" width="132">TLB-6300</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl63" height="20" style="height:15.0pt;width:99pt" width="132">Laser controller</td>
			<td class="xl63" style="width:99pt" width="132">Newport</td>
			<td class="xl63" style="width:99pt" width="132">TLB-6300-LN</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">Frequency locking feedback controller</td>
			<td class="xl63" style="width:99pt" width="132">Toptica Photonics</td>
			<td class="xl63" style="width:99pt" width="132">Digilock 110</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">Auto-balanced photoreceiver</td>
			<td class="xl63" style="width:99pt" width="132">Newport</td>
			<td class="xl63" style="width:99pt" width="132">Model 2007</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">In-line polarization controller</td>
			<td class="xl63" style="width:99pt" width="132">General Photonics</td>
			<td class="xl63" style="width:99pt" width="132">PLC-003-S-90</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">24-bit data acquisition card</td>
			<td class="xl63" style="width:99pt" width="132">National Instruments</td>
			<td class="xl63" style="width:99pt" width="132">NI-PCI-4461</td>
		</tr>
		<tr height="60" style="height:45.0pt">
			<td class="xl63" height="60" style="height:45.0pt;width:99pt" width="132">Recombinant human interleukin-2</td>
			<td class="xl63" style="width:99pt" width="132">Pierce Biotechnology</td>
			<td class="xl63" style="width:99pt" width="132">R201520</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">20 nm polystyrene beads</td>
			<td class="xl63" style="width:99pt" width="132">Thermo Scientific</td>
			<td class="xl63" style="width:99pt" width="132">3020A</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">NanoCube XYZ Piezo Stage</td>
			<td class="xl63" style="width:99pt" width="132">Physik Instrumente</td>
			<td class="xl63" style="width:99pt" width="132">P-611.3</td>
		</tr>
		<tr height="20" style="height:15.0pt">
			<td class="xl63" height="20" style="height:15.0pt;width:99pt" width="132">Optical table</td>
			<td class="xl63" style="width:99pt" width="132">Newport</td>
			<td class="xl63" style="width:99pt" width="132">VH3660W-OPT</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">Objective lens for imaging column</td>
			<td class="xl63" style="width:99pt" width="132">Navitar Machine Vision</td>
			<td class="xl64">1-60228</td>
		</tr>
		<tr height="40" style="height:30.0pt">
			<td class="xl63" height="40" style="height:30.0pt;width:99pt" width="132">Imaging column (adaptor tube)</td>
			<td class="xl63" style="width:99pt" width="132">Navitar Machine Vision</td>
			<td class="xl65">1-60228</td>
		</tr>
		<tr height="60" style="height:45.0pt">
			<td class="xl63" height="60" style="height:45.0pt;width:99pt" width="132">High-Res CCD camera for imaging column</td>
			<td class="xl63" style="width:99pt" width="132">Edmund Industrial Optics</td>
			<td class="xl64">NT39244</td>
		</tr>
	</tbody>
</table>

label-free single molecule detection using microtoroid optical resonators

아래로 단일 분자 한계 분자의 작은 농도를 검출하는 것은 이러한 질병의 조기 발견 및 분자의 행동에 기초 연구 등의 분야에 영향을 미친다. 단일 분자 검출 기술은 일반적 그러나, 라벨 비용 및 복잡성을 증가, 항상 사용할 수 없으며, 이벤트가 연구되고있다 교란 형광 태그 또는 양자점과 같은 라벨을 사용한다. 광학 공진기는 라벨의 사용없이 하나의 분자를 검출하는 수단으로서 유망 나왔다. 현재 용액에 비 plasmonically 향상된 베어 광 공진기 장치에 의해 검출 된 가장 작은 입자는 25 nm의 폴리스티렌 구 1이다. 우리는 위스퍼 에바 네 센트 광 공진기 수용액 2 라벨없는 단일 분자 검출이 한계를 능가 달성 (FLOWER)를 잠그기 주파수로 알려진 기술을 개발했다. 신호 강도가 입자 볼륨 확장, 우리의 작품은&gt; 100 배의 양식 개선을 나타냅니다NT 기술의 현재 상태 위에 잡음비 (SNR)에 신호한다. 여기 FLOWER 뒤에 절차 야전에서의 사용을 증가시키기위한 노력으로 제시된다.

이벤트를 결합 입자는 분명히 시간 (그림 2A)를 통해 microtoroid의 공진 파장의 단계와 같은 변화로 볼 수 있습니다. 이러한 단계 높이는.도 2b에 도시 된 바와 같이, 히스토그램은 각각 2-4, 대표 엑소 좀의 결합에서 트레이스 (nanovesicles), 5 nm의 실리카 비드, 및 단일 인간 인터루킨 2 분자를 표시하는 도면이다. 계단 형 이벤트 입경 확장된...

Watch this Scientific Journal Video about Label-free Single Molecule Detection Using Microtoroid Optical Resonators at JoVE.com

Label-free Single Molecule Detection Using Microtoroid Optical Resonators

We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented.

Microtoroid 광 공진기를 사용하여 라벨이없는 단일 분자 검출

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental ...

label-free-single-molecule-detection-using-microtoroid-optical

Research

JoVE Journal

Bioengineering

9.1K 조회수.  California Institute of Technology. We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented. 

비디오: Label-free Single Molecule Detection Using Microtoroid Optical Resonators

Multiplexed Single-molecule Force Proteolysis Measurements Using Magnetic Tweezers

The generation and detection of mechanical forces is a ubiquitous aspect of cell physiology, with direct relevance to cancer metastasis1, atherogenesis2 and wound healing3. In each of these examples, cells both exert force on their surroundings and simultaneously enzymatically remodel the extracellular matrix (ECM). The effect of forces on ECM has thus become an area of considerable interest due to its likely biological and medical importance4-7.
	Single molecule techniques such as optical trapping8, atomic force microscopy9, and magnetic tweezers10,11 allow researchers to probe the function of enzymes at a molecular level by exerting forces on individual proteins. Of these techniques, magnetic tweezers (MT) are notable for their low cost and high throughput. MT exert forces in the range of ~1-100 pN and can provide millisecond temporal resolution, qualities that are well matched to the study of enzyme mechanism at the single-molecule level12. Here we report a highly parallelizable MT assay to study the effect of force on the proteolysis of single protein molecules. We present the specific example of the proteolysis of a trimeric collagen peptide by matrix metalloproteinase 1 (MMP-1); however, this assay can be easily adapted to study other substrates and proteases.

In this article we describe the use of magnetic tweezers to study the effect of force on enzymatic proteolysis at the single molecule level in a highly parallelizable manner.

마그네틱 족집게를 사용하여 다중 단일 분자 강제 Proteolysis 측정

The  generation and detection of mechanical forces is a ubiquitous aspect of cell physiology,  with direct relevance to cancer metastasis1, atherogenesis2 ...

연구

생체공학

A Cre-Lox P Recombination Approach for the Detection of Cell Fusion In Vivo

The ability of two or more cells of the same type to fuse has been utilized in metazoans throughout evolution to form many complex organs, including skeletal muscle, bone and placenta. Contemporary studies demonstrate fusion of cells of the same type confers enhanced function. For example, when the trophoblast cells of the placenta fuse to form the syncytiotrophoblast, the syncytiotrophoblast is better able to transport nutrients and hormones across the maternal-fetal barrier than unfused trophoblasts1-4. More recent studies demonstrate fusion of cells of different types can direct cell fate. The "reversion" or modification of cell fate by fusion was once thought to be limited to cell culture systems. But the advent of stem cell transplantation led to the discovery by us and others that stem cells can fuse with somatic cells in vivo and that fusion facilitates stem cell differentiation5-7. Thus, cell fusion is a regulated process capable of promoting cell survival and differentiation and thus could be of central importance for development, repair of tissues and even the pathogenesis of disease.
Limiting the study of cell fusion, is lack of appropriate technology to 1) accurately identify fusion products and to 2) track fusion products over time. Here we present a novel approach to address both limitations via induction of bioluminescence upon fusion (Figure 1); bioluminescence can be detected with high sensitivity in vivo8-15. We utilize a construct encoding the firefly luciferase (Photinus pyralis) gene placed adjacent to a stop codon flanked by LoxP sequences. When cells expressing this gene fuse with cells expressing the Cre recombinase protein, the LoxP sites are cleaved and the stop signal is excised allowing transcription of luciferase. Because the signal is inducible, the incidence of false-positive signals is very low. Unlike existing methods which utilize the Cre/LoxP system16, 17, we have incorporated a "living" detection signal and thereby afford for the first time the opportunity to track the kinetics of cell fusion in vivo.
To demonstrate the approach, mice ubiquitously expressing Cre recombinase served as recipients of stem cells transfected with a construct to express luciferase downstream of a floxed stop codon. Stem cells were transplanted via intramyocardial injection and after transplantation intravital image analysis was conducted to track the presence of fusion products in the heart and surrounding tissues over time. This approach could be adapted to analyze cell fusion in any tissue type at any stage of development, disease or adult tissue repair.

A Cre-Lox P Recombination Approach for the Detection of Cell Fusion In Vivo

A method to track cell fusion in living organisms over time is described. The approach utilizes Cre-LoxP recombination to induce luciferase expression upon cell fusion. The luminescent signal generated can be detected in living organisms using biophotonic imaging systems with a sensitivity of detection of &tilde;1,000 cells in peripheral tissues.

세포 융합의 탐지를위한 Cre - 훈제 연어 P 재조합 접근법 VIVO에서</em

The ability of two or more cells of the same type to fuse has been utilized in metazoans throughout evolution to form many complex organs, including ...

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

라만 분광학을 사용하여 세포와 세포외 기질의 비 접촉, 레이블이없는 모니터링

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

A label-free optical biosensor based on a nanostructured porous Si is designed for rapid capture and detection of Escherichia coli K12 bacteria, as a model microorganism. The biosensor relies on direct binding of the target bacteria cells onto its surface, while no pretreatment (e.g.&#160;by cell lysis) of the studied sample is required. A mesoporous Si thin film is used as the optical transducer element of the biosensor. Under white light illumination, the porous layer displays well-resolved Fabry-P&#233;rot fringe patterns in its reflectivity spectrum. Applying a fast Fourier transform (FFT) to reflectivity data results in a single peak. Changes in the intensity of the FFT peak are monitored. Thus, target bacteria capture onto the biosensor surface, through antibody-antigen interactions, induces measurable changes in the intensity of the FFT peaks, allowing for a &#39;real time&#39; observation of bacteria attachment.
The mesoporous Si film, fabricated by an electrochemical anodization process, is conjugated with monoclonal antibodies, specific to the target bacteria. The immobilization, immunoactivity and specificity of the antibodies are confirmed by fluorescent labeling experiments. Once the biosensor is exposed to the target bacteria, the cells are directly captured onto the antibody-modified porous Si surface. These specific capturing events result in intensity changes in the thin-film optical interference spectrum of the biosensor. We demonstrate that these biosensors can detect relatively low bacteria concentrations (detection limit of 104 cells/ml) in less than an hour.

Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

A label-free optical biosensor for rapid bacteria detection is introduced. The biosensor is based on a nanostructured porous Si, which is designed to directly capture the target bacteria cells onto its surface. We use monoclonal antibodies, immobilized onto the porous transducer, as the capture probes. Our studies demonstrate the applicability of these biosensors for the detection of low bacterial concentrations within minutes with no prior sample processing (such as cell lysis).

의 광학 검출<em&gt; E. 대장균</em메조 포러스 실리콘 바이오 센서에 의해&gt; 박테리아

A label-free optical biosensor based on a nanostructured porous Si is designed for rapid capture and detection of Escherichia coli K12 bacteria, as a ...

Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma membrane1. To regulate neuronal excitability, the biophysical properties of ion channels are modified by signaling proteins and molecules, which often bind to the channels themselves to form a heteromeric channel complex2,3. Traditional assays examining the interaction between channels and regulatory proteins require exogenous labels that can potentially alter the protein&#39;s behavior and decrease the physiological relevance of the target, while providing little information on the time course of interactions in living cells. Optical biosensors, such as the X-BODY Biosciences BIND Scanner system, use a novel label-free technology, resonance wavelength grating (RWG) optical biosensors, to detect changes in resonant reflected light near the biosensor. This assay allows the detection of the relative change in mass within the bottom portion of living cells adherent to the biosensor surface resulting from ligand induced changes in cell adhesion and spreading, toxicity, proliferation, and changes in protein-protein interactions near the plasma membrane. RWG optical biosensors have been used to detect changes in mass near the plasma membrane of cells following activation of G protein-coupled receptors (GPCRs), receptor tyrosine kinases, and other cell surface receptors. Ligand-induced changes in ion channel-protein interactions can also be studied using this assay. In this paper, we will describe the experimental procedure used to detect the modulation of Slack-B sodium-activated potassium (KNa) channels by GPCRs.

Optical biosensor techniques can detect changes in mass near the plasma membrane in living cells and allow one to follow cellular responses in both individual cells and populations of cells. This protocol will describe detection of the modulation of potassium channels by G-protein coupled receptors in intact cells using this approach.

G-단백질 결합 수용체에 의해 칼륨 채널의 변조를 감지하기 위해 라벨이없는 광 바이오 센서의 사용

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma ...

Nanomanipulation of Single RNA Molecules by Optical Tweezers

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be increasingly important. As RNA function often depends on its ability to adopt alternative structures, it is difficult to predict RNA three-dimensional structures directly from sequence. Single-molecule approaches show potentials to solve the problem of RNA structural polymorphism by monitoring molecular structures one molecule at a time. This work presents a method to precisely manipulate the folding and structure of single RNA molecules using optical tweezers. First, methods to synthesize molecules suitable for single-molecule mechanical work are described. Next, various calibration procedures to ensure the proper operations of the optical tweezers are discussed. Next, various experiments are explained. To demonstrate the utility of the technique, results of mechanically unfolding RNA hairpins and a single RNA kissing complex are used as evidence. In these examples, the nanomanipulation technique was used to study folding of each structural domain, including secondary and tertiary, independently. Lastly, the limitations and future applications of the method are discussed.

Optical tweezers have been used to study RNA folding by stretching individual molecules from their 5&#8217; and 3&#8217; ends. Here common procedures are described to synthesize RNA molecules for tweezing, calibration of the instrument, and methods to manipulate single molecules.

광 핀셋으로 단일 RNA 분자의 Nanomanipulation

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be ...

A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration of pre-processing steps. Utilizing these devices towards the analysis of DNA hybridization events is important because it offers a technology for real time assessment of biomarkers at the point-of-care for various diseases. However, when the device footprint decreases the dominance of various physical phenomena increases. These phenomena influence the fabrication precision and operation reliability of the device. Therefore, there is a great need to accurately fabricate and operate these devices in a reproducible manner in order to improve the overall performance. Here, we describe the protocols and the methods used for the fabrication and the operation of a microfluidic-based electrochemical biochip for accurate analysis of DNA hybridization events. The biochip is composed of two parts: a microfluidic chip with three parallel micro-channels made of polydimethylsiloxane (PDMS), and a 3 x 3 arrayed electrochemical micro-chip. The DNA hybridization events are detected using electrochemical impedance spectroscopy (EIS) analysis. The EIS analysis enables monitoring variations of the properties of the electrochemical system that are dominant at these length scales. With the ability to monitor changes of both charge transfer and diffusional resistance with the biosensor, we demonstrate the selectivity to complementary ssDNA targets, a calculated detection limit of 3.8 nM, and a 13% cross-reactivity with other non-complementary ssDNA following 20 min&#160;of incubation. This methodology can improve the performance of miniaturized devices by elucidating on the behavior of diffusion at the micro-scale regime and by enabling the study of DNA hybridization events.

We present a microfluidic-based electrochemical biochip for DNA hybridization detection. Following ssDNA probe functionalization, the specificity, sensitivity, and detection limit are studied with complementary and non-complementary ssDNA targets. Results illustrate the influence of the DNA hybridization events on the electrochemical system, with a detection limit of 3.8 nM.

라벨없는 DNA의 혼성화 분석 용 미세 유체 기반 전기 바이오칩

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration ...

A Label-free Technique for the Spatio-temporal Imaging of Single Cell Secretions

Inter-cellular communication is an integral part of a complex system that helps in maintaining basic cellular activities. As a result, the malfunctioning of such signaling can lead to many disorders. To understand cell-to-cell signaling, it is essential to study the spatial and temporal nature of the secreted molecules from the cell without disturbing the local environment. Various assays have been developed to study protein secretion, however, these methods are typically based on fluorescent probes which disrupt the relevant signaling pathways. To overcome this limitation, a label-free technique is required.
In this paper, we describe the fabrication and application of a label-free localized surface plasmon resonance imaging (LSPRi) technology capable of detecting protein secretions from a single cell. The plasmonic nanostructures are lithographically patterned onto a standard glass coverslip and can be excited using visible light on commercially available light microscopes. Only a small fraction of the coverslip is covered by the nanostructures and hence this technique is well suited for combining common techniques such as fluorescence and bright-field imaging.
A multidisciplinary approach is used in this protocol which incorporates sensor nanofabrication and subsequent biofunctionalization, binding kinetics characterization of ligand and analyte, the integration of the chip and live cells, and the analysis of the measured signal. As a whole, this technology enables a general label-free approach towards mapping cellular secretions and correlating them with the responses of nearby cells.

Inter-cellular communication is critical for controlling various physiological activities within and outside the cell. This paper describes a protocol for measuring the spatio-temporal nature of single cell secretions. To achieve this, a multidisciplinary approach is used which integrates label-free nanoplasmonic sensing with live cell imaging.

단일 세포 분비물의 공간 - 시간 영상의 레이블이없는 기술

Inter-cellular communication is an integral part of a complex system that helps in maintaining basic cellular activities. As a result, the malfunctioning ...

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 ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

물방울 미세 유체에 대한 여러 가지 빛깔의 형광 검출 광학 섬유를 사용하여

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...