Colloidally stable and highly luminescent near-IR emitting Ag 2 S quantum dots (NIRQDs) were prepared by a very simple aqueous method using 2-mercaptopropionic acid (2MPA) as a coating. Emission of Ag 2 S-2MPA NIRQDs can be tuned between 780 and 950 nm. These NIRQDs have photoluminescence quantum yields (PLQY) around 7-39% and exhibit excellent cytocompatibility even at 600 mg mL À1 in NIH/3T3 cells. With such improved properties, Ag 2 S-2MPA NIRQDs have a great potential in practical bio-applications.
The development of non-toxic theranostic nanoparticles capable of delivering a therapeutic cargo and providing a means for diagnosis is one of the most challenging tasks in nano-biotechnology. Gene therapy is a very important mode of therapy and polyethyleneimine (PEI) is one of the most successful vehicles for gene transfection, yet poses significant toxicity. Optical imaging utilizing quantum dots is one of the newer but fast growing diagnostic modalities, which requires non-toxic, highly luminescent materials, preferentially active in the near infrared region. Ag2S NIRQDs fit to this profile perfectly. Here, we demonstrate the aqueous synthesis of cationic Ag2S NIRQDs with a mixed coating of 2-mercaptopropionic acid (2MPA) and PEI (branched, 25 kDa), which are highly luminescent in the NIR-I window (λem = 810-840 nm) as new theranostic nanoparticles. Synergistic stabilization of the QD surface via the simultaneous use of a small molecule and a polymeric material provided the highest quantum yield, 150% (with respect to LDS 798 at pH 7.4), reported in the literature for Ag2S. These cationic particles show a dramatic improvement in cytocompatibility even without PEGylation, a strong optical signal easily detected by confocal laser microscopy and effective conjugation and transfection of the green fluorescence protein plasmid (pGFP) to HeLa and MCF-7 cell lines (40% efficiency). Overall, these Ag2S NIRQDs show great potential as new theranostics.
Size tunable aqueous Ag2S quantum dots emitting in the near-infrared region were synthesized through decomposition of meso-2,3-dimercaptosuccinic acid (DMSA) in water. The resulting NIR QDs are highly cyto- and hemocompatible, have quantum yields as high as 6.5% and are effective optical imaging agents based on in vitro evaluation.
Gümüş sülfür (Ag 2 S) kuantum noktaları (QD), hem görüntüleme hem de ilaç/gen hedefleme için büyük aktiviteleri nedeniyle biyo-görüntüleme sisteminde oldukça gelecek vaad eden nanomalzemelerdir. Mezo-2,3-dimerkaptosüksinik asit (DMSA) ile kaplanmış Ag 2 S QD'lerin toksisitesi hakkında yeterli çalışma yoktur. Bu çalışmada Çin hamster akciğer fibroblast (V79) hücrelerinde DMSA ile kaplanmış Ag 2 S QD'lerin geniş bir konsantrasyon aralığında (5-2000 µg/mL) sitotoksisitesini belirlemeyi amaçladık. Gereç ve Yöntemler: Hücre canlılığı 3-(4,5-dimetiltiyazol-2-il)-2,5-difeniltetrazolium bromid (MTT) ve nötral kırmız alım (NRU) deneyleri ile belirlendi. DMSA/Ag 2 S QD'lerin genotoksik ve apoptotik etkileri sırasıyla komet analizi ve gerçek zamanlı polimeraz zincir reaksiyonu tekniği ile değerlendirildi. Bulgular: Ag 2 S QD'lerin en yüksek dozlarında hücre canlılığı MTT ve NRU deneylerinde sırasıyla 54.0±4.8% ve 65.7±4.1% olarak bulundu. Ancak hücre canlılığı 400 µg/mL (MTT deneyi) ve 800 µg/mL (NRU deney) üzerinde azalmıştır. İncelenen konsantrasyonlarda DNA hasarının DMSA/Ag 2 S QD'ler tarafından indüklenmediği belirlenmiştir. P53, kaspaz-3, kaspaz-9, Bax, Bcl-2 ve survivin genlerinin mRNA ekspresyon düzeyleri 500 ve 1000 µg/mL DMSA/Ag 2 S QD'lere maruz kalan hücrelerde değişmiştir. Sonuç: DMSA/Ag 2 S QD'lerin yüksek dozlarda sitotoksik etkilerinin apoptotik yollarla ortaya çıkabileceği görülmektedir. Bununla birlikte, DMSA/ Ag 2 S QD'ler, düşük dozlarda biyolojik olarak uyumlu görünmektedir, bu da onları hücre görüntüleme uygulamaları için uygun kılmaktadır.
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