저자는 기꺼이이 프로젝트의 그들의 지원을 위해 미주리 주립 대학에서 화학학과 및 대학원 대학을 인정합니다. 우리는 또한, 투과 전자 현미경 탄소 코팅 된 그리드의 사용 암 연구 프레드릭 국립 연구소 전자 현미경 실험을 인정한다.

인듐 인화물 / 황화 아연 (InP를 /의 ZnS) 양자 점의 1. 합성 <ol><li> 인듐 포스 파이드 (InP)와 같은 반도체 양자점 코어의 합성 <ol><li> 12 인치 응축기 100 ㎖ 둥근 바닥 3 목 플라스크에 장착한다. 올레 일 아민 30 ㎖ (OLA), 0.398 g의 인듐 (III) 클로라이드 (3 포함), 0.245 g의 아연 (II) 클로라이드 (ZnCl 2)를 첨가하고 1 시간 동안 진공을 사용하여 RT에서 배기하면서 교반한다. 이 솔루션은 흰색 침전물과 무색 나타납니다. </li><li> 열전쌍 및 비례 적분 미분 (PID) 온도 제어기로 가열 맨틀을 사용하여, 120 ° C까지 용액의 온도를 증가시킨다. 코어의 성장에 영향을 미칠 수있는 저비점 불순물을 제거하고 20 분 동안 진공 하에서 용액 대피. 주의 : 가열 맨틀을 사용하여 모래 욕 및 온도계를 사용할 수 있고 PID가 반응 생성물의 균일 성 및 재현성을 향상 동안. </li><li> 불활성 가스에서 (예를 들어,, N 2) 용액을 환류하에 15 분 동안 220 ℃까지 온도를 증가시킨다. 포함 3 ZnCl 2 완전히 담황색 용액 결과 녹인다. 온도가 10 분 동안 안정화 할 수 있습니다. </li><li> 일회용 3 ㎖ 플라스틱 주사기 및 4 인치, 질소 가스를 22 G 바늘을 제거. 주사기를 사용하여 신속하게 포함 3 용액에 0.5 ㎖의 트리스 (디메틸 아미노) 포스 핀 (TDMAP)를 제공한다. 용액의 온도가 약간 감소하고 220 ° C까지 돌아갑니다. 투명에서 솔루션을 변경, 블랙, 불투명 한 노란색 창백. </li><li> 온도가 200 ° C 이하로 감소 될 때까지 9.5 분 후, 가열 맨틀로부터 반응 플라스크를 제거한다. InP의 코어의 무결성을 보호하기 위해 단계 1.2.1에서의 ZnS 코팅에 직접 진행합니다. </li></ol></li><li> 황화 아연 (의 ZnS) 양자 도트 쉘의 합성 <ol><li> 가열 맨틀에 단계 1.1.5에서 반응 플라스크를 놓고 t을 안정200 ° C에서 럼 온. 천천히 InP를 양자점을 함유하는 용액에 15 초에 걸쳐 3.58 g의 도데 칸 티올 (DDT)을 추가한다. 용액을 1 시간 동안 반응 할 수 있습니다. 참고 인 ZnS 쉘 두께를 증가 시키거나 단계 1.2.4 첨가 아연 스테아 레이트의 양을 감소시킴으로써 변화 될 수있다. 단계 1.1.1 및 1.2.1에 ZnCl 2의 양을 변경하거나 도데 상당히 반응 속도를 변화시킴으로써 양자점의 품질에 영향을 미칠 수있다. <ol><li> 그 후, 가열 맨틀로부터 반응 플라스크를 제거하고, 용액을 약 60 ℃로 냉각 할 수있다. </li></ol></li><li> InP의 / 인 ZnS 용액 이르면 ~ 60 ° C 10 ml의 헥산을 부가하고 50 ㎖ 폴리 프로필렌 원심 분리 튜브에 약 45 ㎖의 전체 용액 옮긴다. 미 반응 고체 전구체를 제거하기 위해 샘플 (10 분 동안 3,000 XG)를 원심 분리기. </li><li> 조심스럽게 (원심 분리기 3,000 X를 솔루션을 250 ml의 폴리 프로필렌 원심 분리기 병에 뜨는을 전송 200ml의 아세톤을 추가하고,10 분)에 대한 g을 InP를 /의 ZnS 양자점을 침전합니다. 필요한 로터 / 액세서리 원심 분리기를 사용할 수없는 경우이 볼륨은 원심 분리에 대해 사 50 ㎖ 튜브에 균등하게 분할 할 수 있습니다. 뜨는을 가만히 따르다 및 아세톤을 제거하기 위해 질소 가스로 완전히 QD 펠렛을 건조. </li><li> 초음파 처리를 사용하여 20 ㎖ OLA에 재현 탁 양자점을 50 ㎖ 둥근 바닥 3 목 플라스크에 0.474 g 함유 아연 스테아 레이트 및 교반 옮긴다. 실온에서 20 분 동안 진공 솔루션을 대피. </li><li> 질소 하에서 180 ℃까지 온도를 증가시키고, 반응을 3 시간 동안 수행 할 수있다. 반응 중에 발생하는 반응 액에 띄는 시각적 변화가 없지만 스테아린산 아연을 첨가하여 이렇게 양자점 (12)의 표면 보호를 개선 QY 증가의 ZnS 쉘 두께를 증가시킨다. 상기 반응이 완료되면, 가열 맨틀로부터 플라스크를 제거 상기 용액을 약 60 ℃로 냉각 할 수있다. </li><li> InP를 /의 ZnS soluti 번에 도달 ~ 60 ° C 20 ml의 헥산을 부가하고 50 ㎖ 폴리 프로필렌 원심 분리 튜브로 옮긴다. 미 반응의 아연 스테아 레이트를 제거하기 위해 샘플 (10 분 동안 3,000 XG)를 원심 분리기. </li><li> 조심스럽게, 250 ml의 폴리 프로필렌 원심 분리기 병에 뜨는을 전송 InP를 /의 ZnS 양자점을 침전 200ml의 아세톤, 원심 분리 용액 (10 분 3,000 XG)를 추가합니다. 조심스럽게 뜨는을 가만히 따르다 및 아세톤을 제거하기 위해 질소 가스로 완전히 건조. </li><li> 30 ml의 헥산의 InP /의 ZnS QD 펠렛을 녹인다. 소용돌이와는 완전한 분산을 보장하기 위해 잠시 솔루션을 초음파 처리. </li><li> 반복 정제를 초과하는 유기 리간드의 철저한 제거를 보장하기 위해 1.2.6-1.2.8 두 번 더 반복합니다. 양친 매성 고분자 단계 1.2 QD 사이의 상호 작용이 과잉의 리간드의 존재 하에서 저하 될 수있다. </li><li> 시에 의해 설명 계산, 등. (16), UV-마주 분광학 사용하여 합성 된 InP를 /의 ZnS 양자점의 크기와 농도를 결정한다. <br/&gt; 주 :이 해석 중요한 분광 특성 흡수 피크의 숄더이다. 이 어깨의 최대 파장과 흡광도 값은 각각 크기 및 양자점의 농도를 계산하는데 사용된다. 이 반응은 전형적으로 600 nm에서 발광 피크와 약 5 μmol의 양자점을 산출한다. 다른 색상의 양자점을 합성 반응의 지속 시간 및 / 또는 온도를 변경할 수있다. 긴 반응 시간 및 / 또는 적색 편이 방출 피크 용액 결과 고온. 예를 들어, 10 분, 240 ℃까지 반응 온도를 증가시키고, 반응 유지 시간은 최대 680 nm의 방출 피크 양자점을 초래할 것이다. 마찬가지로, 2 분으로 반응 시간을 감소시키고 470 nm의 최대 발광 피크 양자점 될 것이다 사용 염화 아연 배로. 이들의 InP / 인 ZnS 양자점은 불활성 기체하에 어둠 속에서 4 ℃에서 1 개월 이상 동안 안정하다. </li></ol></li></ol> 2. 물양친 매성 고분자를 사용하여 InP를 /의 ZnS 양자점의 가용화 <ol><li> 물 가용화 <ol><li> 단계 1.2.10에서의 InP / 양자점은 ZnS를 사용하여 1 μM 양자점 1 ㎖를 수득 헥산으로 양자점의 일부를 희석. <ol><li> 원심 분리 관에서 각 튜브에 0.25 mL의의 InP / 양자점은 ZnS 옮긴다. 원심 분리기 튜브와 원심 분리기 (10 분 3,000 XG)에 1 ml의 아세톤 또는 메탄올을 추가합니다. 조심스럽게 상층 액을 제거하고 1 ml의 테트라 하이드로 퓨란 (THF)에 각각의 침전물을 용해. </li><li> 100ml의 둥근 바닥 플라스크에 THF에 용해 InP를 /의 ZnS 양자점을 전송하고 16 ML의 THF로 희석. 용액의 응집체의 수를 감소 5-10 분 동안 초음파 처리 양자점한다. </li></ol></li><li> 10 ㎖의 분자량 등급 물에 30 mg의 폴리 (말레 andhydride- ALT -1- 옥타 데센), 3- (디메틸 아미노) -1- 프로필 아민 (PMAL-D)를 녹인다. 용액이 투명해질 때까지 수조에서 초음파 또는 부드러운 교반은 중합체를 완전히 용해하기에 충분하다. 그만큼소용돌이 나 격렬한 교반 사용 QD로 중합체의 상호 작용을 방해하는 많은 거품을 생성 할 수있다. 라운드 THF에서의 InP /의 ZnS 양자점을 포함하는 바닥 플라스크 100 ㎖에 10 ml의 폴리머 솔루션을 추가합니다. </li><li> 회전 증발기를 사용 QD / 중합체 용액으로부터 THF를 증발시켰다. 중합체 및 QD 사이의 상호 작용을 용이하게하기 위해 증착 동안 얼음 용기에 플라스크를 배치. 진공의 강도에 따라, 대부분의 THF 10 분 후에 증발시키고, 용액을 혼탁 나타난다. <ol><li> 용액을 10 ㎖로 증발되면, 회전식 증발기에서 제거하고, 플라스크를 30 ㎖을 분자 수준의 물을 첨가 하였다. 회전 증발기에 플라스크를 돌려 2 ml의 증발을 계속합니다. 이 최종 증발 단계는 많은 시간이 걸릴 수 있습니다; 얼음 목욕이 유지되어 있는지 확인합니다. </li></ol></li><li> 피펫 둥근 바닥 플라스크에서 수용성의 InP /의 ZnS 양자점을 제거합니다. 0.1㎛의 나일론 SY 부착 3 ㎖ 플라스틱 주사기를 사용 QD 용액 필터ringe는 5 ML의 원심 분리기 튜브에 필터링 할 수 있습니다. </li><li> 20,000 MWCO 막 투석 장치에 양자점을 놓고 여분의 중합체를 제거하기 위해 0.05 M 붕산 완충액 pH 8.5에 대해 투석. (pH가이 붕산 완충액을 8.5가 될 때까지 천천히 격렬한 교반과 함께, 0.05 M 붕산 0.05 M 소듐 테트라 보레이트 십수화물을 추가한다.) 진공 농축기를 사용하여 1 ml의 보레이트 완충액에 양자점을 농축시킨다. </li><li> 저장을 위해, 파라 필름으로 밀봉하기 전에 질소 가스 퍼지 용액. 수용성의 InP /의 ZnS 양자점은 어둠 속에서 4 ° C에서 최소 4 개월 동안 안정하다. </li></ol></li></ol>

<ol>
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N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relative+fluorescence+quantum+yields+using+a+computer-controlled+luminescence+spectrometer.">Relative fluorescence quantum yields using a computer-controlled luminescence spectrometer.</a> Analyst. 108, 1067-1071 (1983).</li><li>Schindelin, 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=Fiji:+An+open-source+platform+for+biological-image+analysis.">Fiji: An open-source platform for biological-image analysis.</a> Nat. Methods. 9 (7), 676-682 (2012).</li><li>Schnieder, C. A., Rasband, W. S., Eliceiri, K. 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Toxicol. 20 (8), 1126-1133 (2007).</li><li>Corazzari, I., Gilardino, A., Dalmazzo, S., Fubini, B., Lovisolo, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localization+of+CdSe/ZnS+quantum+dots+in+the+lysosomal+acidic+compartment+of+cultured+neurons+and+its+impact+on+viability:+potential+role+of+ion+release.">Localization of CdSe/ZnS quantum dots in the lysosomal acidic compartment of cultured neurons and its impact on viability: potential role of ion release.</a> Toxicol. In Vitro. 27 (2), 752-759 (2013).</li><li>Pons, T., Uyeda, H. T., Medintz, I., Mattoussi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrodynamic+dimensions,+electrophoretic+mobility,+and+stability+of+hydrophilic+quantum+dots.">Hydrodynamic dimensions, electrophoretic mobility, and stability of hydrophilic quantum dots.</a> J. Phys. Chem. B. 110 (41), 20308-20316 (2006).</li><li>Durisic, N., Wiseman, P., Grutter, P., Heyes, C. 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저자는 공개 아무것도 없어.

이 프로토콜은 많은 생물학적 시스템에서 사용할 수있는 매우 형광체의 InP / 인 ZnS 양자점의 합성 세부. 여기에 합성 QD 제품은 전술 한 다른 비교 합성 12 내지 73 (도 1)의 FWHM, 600 nm에서 중심 단일 형광 발광 피크를 나타내었다. 반응 시간과 반응 온도 QD 합성 품질 및 재현성에 미치는 큰 영향으로 인해 매우 중요한 단계이다. 물에 용해 후, 양자점은 약 6 %의 양자 수율을하기로 ...

A correction was made to: <a href="http://www.jove.com/video/53684/synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical" target="_blank">Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications</a>. There was an error with an author's given name. The author's name was corrected to:
Katye M. Fichter
from:
Kathryn M. Fichter

A correction was made to: <a href="http://www.jove.com/video/53684/synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical" target="_blank">Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications</a>.

Erratum: Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

양자 도트 (양자점)는 빛 (1) 조사에 형광 특성을 나타내는 나노 결정 반도체된다. 그들의 작은 많은 큰 생체 분자와 비슷합니다 크기 (2-5 ㎚), 및 biofunctionalization의 용이성, 양자점은 생명 의학 애플리케이션을위한 매우 매력적인 도구입니다. 그들은 생물학적 표지의 사용을 발견 한 많은 다른 용도 2-8 사이의 단일 분자 라이브 세포 이미징, 약물 전달, 생체 이미징, 병원체 탐지 및 세포 추적. CD 기반 양자점 가장 일반적으로 인해 강한 형광 좁은 발광 피크 폭 (9)의 생의학 분야에 사용되어왔다. 그러나 우려 인해 카드뮴의 잠재적 인 독성 제기되고있다 2+ 나노 입자의 분해를 통해 공개 할 수있다 (10)를 이온. 그들은 많은 형광 특성을 유지하기 때문에, 최근의 InP 계 양자점 CD 기반 양자점 대안으로 탐구되어왔다의 양자점을 CD 기반과 11 개의 생체 적합성 수있다. CD 기반 양자점은 48 시간 11 후 10 오후의 낮은 농도에서 시험 관내 분석에서의 InP 기반의 양자점보다 훨씬 더 독성이 밝혀졌다. 양자점의 형광 방출 색상은 가변 크기 일 것이다. 즉 QD 크기가 증가, 형광 방출은 적색 편이된다. QD 상품의 크기 및 크기 분산은 반응 12시 온도, 반응 지속 시간, 또는 전구체 농도 조건을 변경함으로써 변경 될 수있다. InP의 양자점의 발광 피크는 일반적으로 넓은 그리고 CD 기반 양자점보다 강한 반면, InP를 양자점은 스펙트럼 중첩을 방지하기위한 수많은 색상 다양한 이루어진 것으로, 대부분 생물 의학 응용 (12)을 충분히 강렬 할 수있다. 이 프로토콜에 설명 합성은 600 nm에서 중심 적색 발광 피크 양자점을 산출한다. 몇 가지 단계가 AF 촬영QD 코어 터 합성은 양자점의 광학 무결성을 유지하고 생물 애플리케이션에 호환되도록 할 수 있습니다. QD 코어의 표면은 담금질의 원인이 산화 또는 표면 결함으로부터 보호되어야한다 따라서, 쉘은 ZnS의 InP /의 ZnS (코어 / 쉘) 13 양자점을 제조 코어 위에 코팅된다. 이 코팅은 QD 상품의 광 발광을 보호하는 것으로 나타났다. InP의 QD 합성 중에 아연 이온의 존재는 표면 결함의 감소뿐만 아니라 입도 분포 (12)를 제한하는 것으로 나타났다. 비록 반응 매질에서 아연 2+의 존재와 InZnP의 합성 12 희박하다. 코팅 후, 결과의 InP /의 ZnS 양자점은 이러한 트리 옥틸 포스 핀 옥사이드 (TOPO) 또는 올레 일 아민 (12, 14)과 같은 소수성 리간드에 코팅된다. 양쪽 성 중합체는 수용성을 부여하는 15 QD 표면의 소수성 리간드뿐만 아니라 대량의 물 분자와 상호 작용할 수있다. 침탄와 양친 매성 고분자xylate 화학 기는 상기 양자점을 기능화 &quot;화학 핸들&quot;로서 사용될 수있다. 이 프로토콜은 매우 강렬한 형광 방출과 상대적으로 작은 크기 분산과 합성 수용성의 InP /의 ZnS 양자점의 작용을 자세히 설명합니다. 이러한 양자점은 잠재적으로 일반적으로 사용의 CdSe /의 ZnS 양자점보다 독성이 낮음. 여기서, InP를 /의 ZnS 양자점의 합성은 생물 의학 응용 프로그램에 대한 CD 기반 양자점에 대한 실질적인 대안을 제공합니다.

<table><tbody><tr><td>Oleylamine</td><td>Acros</td><td>129540010</td><td></td></tr><tr><td>Zinc(II) chloride</td><td>Sigma</td><td>030-003-00-2</td><td></td></tr><tr><td>Indium(III) chloride</td><td>Chem-Impex</td><td>24560</td><td></td></tr><tr><td>Tris(dimethylamino)phosphine</td><td>Encompass</td><td>50-901-10500</td><td></td></tr><tr><td>1-dodecanethiol</td><td>Acros</td><td>117625000</td><td></td></tr><tr><td>Hexanes</td><td>Fisher Sci</td><td>H292-4</td><td></td></tr><tr><td>Acetone</td><td>TransChemical</td><td>UN 1090</td><td></td></tr><tr><td>Zinc Stearate</td><td>Aldrich Chem</td><td>307564-1KG</td><td></td></tr><tr><td>Tetrahydrofuran</td><td>Acros</td><td>34845-0010</td><td></td></tr><tr><td>Molecular Water</td><td>Fisher Sci</td><td>BP2470-1</td><td></td></tr><tr><td>Poly(maleic anhyrdride-&lt;em&gt;alt&lt;/em&gt;-1-tetradecene), 3-(dimethylamino)-1-propylamine derivative</td><td>Sigma</td><td>90771-1G</td><td></td></tr><tr><td>Boric acid</td><td>Fisher Sci</td><td>BP168-500</td><td></td></tr><tr><td>Sodium Tetraborate Decahydrate</td><td>Fisher Sci</td><td>BP175-500</td><td></td></tr><tr><td>Rhodamine B</td><td>Aldrich Chem</td><td>R95-3</td><td></td></tr><tr><td>Nitrogen gas</td><td>Airgas</td><td>UN1066</td><td></td></tr><tr><td>Trypan blue</td><td>Thermo Sci</td><td>SV30084.01</td><td></td></tr><tr><td>3 ml plastic Luer-lock syringe</td><td>BD</td><td>309657</td><td></td></tr><tr><td>Luer-lock Needle</td><td>Air-Tite</td><td>8300014471</td><td>4 inch, 22 gauge</td></tr><tr><td>50 ml polypropyene centrifuge tube</td><td>Falcon</td><td>352098</td><td></td></tr><tr><td>250 ml centrifuge bottle</td><td>Thermo Sci</td><td>05-562-23</td><td>Nalgene PPCO</td></tr><tr><td>5 ml centrifuge tubes</td><td>Argos-Tech</td><td>T2076</td><td></td></tr><tr><td>1.5 ml microcentrifuge tubes</td><td>Bio Plas</td><td>4150</td><td></td></tr><tr><td>0.1 &amp;mu;m Syringe filter</td><td>Whatman</td><td>6786-1301</td><td>Puradisc 13 mm nylon filter</td></tr><tr><td>Slide-A-Lyzer MINI Dialysis Unit</td><td>Thermo Sci</td><td>69590</td><td>20,000 MWCO</td></tr><tr><td>Rotary Evaporator</td><td>Heidolph</td><td></td><td></td></tr><tr><td>Centrifuge 5072</td><td>Eppendorf</td><td></td><td>Swinging Bucket with 50&amp;nbsp;ml tube adapters</td></tr><tr><td>Lambda 650 UV/VIS Spectrometer</td><td>Perkin Elmer</td><td></td><td>UV-Vis Spectrophotometer</td></tr><tr><td>LS 55 Fluorescence Spectrometer</td><td>Perkin Elmer</td><td></td><td>Fluorometer</td></tr><tr><td>Axio Observer.A1</td><td>Zeiss</td><td></td><td>epifluorescence microscope</td></tr><tr><td>AxioCam MRm</td><td>Zeiss</td><td></td><td>CCD Camera</td></tr><tr><td>Tecnai TF20 Microscope</td><td>FEI</td><td></td><td>Transmisison Electron Miscroscope</td></tr><tr><td>TEM Eagle CCD</td><td>FEI</td><td></td><td>TEM CCD Camera</td></tr><tr><td>NanoBrook Omni DLS</td><td>Brookhaven</td><td></td><td>Dynamic Light Scattering Instrument</td></tr></tbody></table>

synthesis of cd-free inp/zns quantum dots suitable for biomedical applications

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, quantum dots should be highly fluorescent and small/monodisperse in size. While commonly used cadmium-based quantum dots possess these qualities, they are potentially toxic due to the possible release of Cd2+ ions through nanoparticle degradation. Indium-based quantum dots, specifically InP/ZnS, have recently been explored as a viable alternative to cadmium-based quantum dots due to their relatively similar fluorescence characteristics and size. The synthesis presented here uses standard hot-injection techniques for effective nanoparticle growth; however, nanoparticle properties such as size, emission wavelength, and emission intensity can drastically change due to small changes in the reaction conditions. Therefore, reaction conditions such temperature, reaction duration, and precursor concentration should be maintained precisely to yield reproducible products. Because quantum dots are not inherently soluble in aqueous solutions, they must also undergo surface modification to impart solubility in water. In this protocol, an amphiphilic polymer is used to interact with both hydrophobic ligands on the quantum dot surface and bulk solvent water molecules. Here, a detailed protocol is provided for the synthesis of highly fluorescent InP/ZnS quantum dots that are suitable for use in biomedical applications.

코팅의 InP 코어는 눈으로 상당한 보이는 형광을 보여주지 않습니다. 그러나, InP를 /의 ZnS (코어 / 쉘) 양자점은 UV 조사에서 눈으로 밝은 형광을 보인다. InP를 /의 ZnS 양자점의 형광은 형광 분광법을 사용하여 분석되었다. 헥산 양자점의 형광 스펙트럼 73 나노 미터의 절반 최대 (FWHM)에서 전체 폭이 600 nm에서 중심으로 한 주요 피크를 보여줍니다 nm의 533에서 여기 (그림 ...

Watch this Scientific Journal Video about Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications at JoVE.com

Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

바이오 메디컬 응용 프로그램에 적합 InP를 /의 ZnS 양자점 CD-자유의 합성

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, ...

synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical

Research

JoVE Journal

Chemistry

13.5K 조회수.  Missouri State University. In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

비디오: Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

단일 분자 이미징을위한 소형 양자 점

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

연구

공학

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

화학

Solubilization and Bio-conjugation of Quantum Dots and Bacterial Toxicity Assays by Growth Curve and Plate Count

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence1,2 3,4,5. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells6.
QDs are also being widely investigated as cytotoxic agents for targeted killing of bacteria. The emergence of multiply-resistant bacterial strains is rapidly becoming a public health crisis, particularly in the case of Gram negative pathogens 7. Because of the well-known antimicrobial effect of certain nanomaterials, especially Ag, there are hundreds of studies examining the toxicity of nanoparticles to bacteria 8. Bacterial studies have been performed with other types of semiconductor nanoparticles as well, especially TiO2 9,10-11, but also ZnO12 and others including CuO 13. Some comparisons of bacterial strains have been performed in these studies, usually comparing a Gram negative strain with a Gram positive. With all of these particles, mechanisms of toxicity are attributed to oxidation: either the photogeneration of reactive oxygen species (ROS) by the particles or the direct release of metal ions that can cause oxidative toxicity. Even with these materials, results of different studies vary greatly. In some studies the Gram positive test strain is reportedly more sensitive than the Gram negative 10; in others it is the opposite 14. These studies have been well reviewed 15.
In all nanoparticle studies, particle composition, size, surface chemistry, sample aging/breakdown, and wavelength, power, and duration of light exposure can all dramatically affect the results. In addition, synthesis byproducts and solvents must be considered16 17. High-throughput screening techniques are needed to be able to develop effective new nanomedicine agents.
CdTe QDs have anti-microbial effects alone18 or in combination with antibiotics. In a previous study, we showed that coupling of antibiotics to CdTe can increase toxicity to bacteria but decrease toxicity to mammalian cells, due to decreased production of reactive oxygen species from the conjugates19. Although it is unlikely that cadmium-containing compounds will be approved for use in humans, such preparations could be used for disinfection of surfaces or sterilization of water.
In this protocol, we give a straightforward approach to solubilizing CdTe QDs with mercaptopropionic acid (MPA). The QDs are ready to use within an hour. We then demonstrate coupling to an antimicrobial agent.
The second part of the protocol demonstrates a 96-well bacterial inhibition assay using the conjugated and unconjugated QDs. The optical density is read over many hours, permitting the effects of QD addition and light exposure to be evaluated immediately as well as after a recovery period. We also illustrate a colony count for quantifying bacterial survival.

Nanoparticles such as semiconductor quantum dots (QDs) can be used to create photoactivatable agents for anti-microbial or anti-cancer applications. This technique shows how to water-solubilize cadmium telluride (CdTe) QDs, conjugate them to an antibiotic, and perform a bacterial inhibition assay based upon growth curves and plate count.

성장 곡선 및 플레이트 카운트하여 양자 점 및 세균성 독성 Assays의 Solubilization 및 바이오 활용

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. ...

생체공학

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

황 합체 매트릭스 내의 자유 리간드의 CDS 나노 입자의 합성

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

직접 형광 이미징을 사용하여 나노 입자 - 고분자 복합 재료의 고급 성분 분석

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

면 대 면 모양 이방성 콜 로이드 카드뮴 칼코게나이드 Nanostructures의 연결

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...

Production and Targeting of Monovalent Quantum Dots

The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in biology, where clustering and the spatial organization of biomolecules is often the object of study. We describe here a protocol to produce monovalent quantum dots (mQDs) that can be accomplished in most biological research laboratories via a simple mixing of CdSe/ZnS core/shell QDs with phosphorothioate DNA (ptDNA) of defined length. After a single ptDNA strand has wrapped the QD, additional strands are excluded from the surface. Production of mQDs in this manner can be accomplished at small and large scale, with commercial reagents, and in minimal steps. These mQDs can be specifically directed to biological targets by hybridization to a complementary single stranded targeting DNA. We demonstrate the use of these mQDs as imaging probes by labeling SNAP-tagged Notch receptors on live mammalian cells, targeted by mQDs bearing a benzylguanine moiety.

We provide detailed instructions for the preparation of monovalent targeted quantum dots (mQDs) from phosphorothioate DNA of defined length. DNA wrapping occurs in high yield, and therefore, products do not require purification. We demonstrate the use of the SNAP tag to target mQDs to cell-surface receptors for live-cell imaging applications.

생산 및 일가 양자점 타겟팅

The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in ...

Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are demonstrated. The ink synthesis is based on a simple wet chemical reaction and the inkjet printing protocol is a facile step by step method. The inkjet printed thin films have been characterized by X-ray diffraction, optical absorption spectroscopy, photoluminescent spectroscopy, and electronic transport measurements. X-ray diffraction of the printed quantum dot films indicates a crystal structure consistent with an orthorhombic room temperature phase with (001) orientation. In conjunction with other characterization methods, the X-ray diffraction&#160;measurements show high quality films can be obtained through the inkjet printing method.

A protocol for synthesizing inorganic-lead-halide hybrid perovskite quantum dot inks for inkjet printing and the protocol for preparing and printing the quantum dot inks in an inkjet printer with post characterization techniques are presented.

태양광 응용 프로그램에 대 한 모든 무기 할로겐 페로 잉크를 인쇄 하는 잉크젯

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

37P 20(o2CR)51 클러스터의 합성 및 InP 양자 점으로의 변환

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...