Studies on CdSe/l-cysteine Quantum Dots Synthesized in Aqueous Solution for Biological Labeling

Abstract

Water-soluble, biologically compatible CdSe quantum dots (QDs) with l-cysteine as capping agent were synthesized in aqueous medium. Fluorescence (FL) spectra, absorption spectra, and transmission electron microscopy studies showed that both the molar ratio of Se/Cd and the reaction time are the determining factors for the size distribution of CdSe/l-cysteine QDs. The interaction of QDs bioconjugated to bovine serum albumin (BSA) was also studied by absorption and FL titration experiments. With addition of QDs, the FL intensity of BSA was largely quenched, which can be explained by static mechanism. However, when BSA was added to the solution of QDs, FL intensity of QDs was faintly enhanced at first and then quenched. Lysozyme could change the Escherchia coli (E. coli) membrane fluidity and permeability by FL polarimetry. Fluorescent imaging suggested that QDs can be designed as a probe to label the E. coli cell. These results suggested CdSe/l-cysteine QDs can be used as a probe for labeling biological molecule and bacteria cell.

A New Class of Nanostructured Inorganic–Organic Hybrid Semiconductors Based on II–VI Binary Compounds

“…Semiconductor QDs bridge the gap between molecules and bulk materials, but the boundaries among molecules, QDs and bulk regimes are not well defined and are material dependent. Over the past 20 years, tremendous research efforts have been made to develop II-VI quantum dots because of their great potential to revolutionize numerous traditional and emerging technologies [e.g., light emitting diodes (LEDs) (37)(38)(39)(40)(41)(42), solar cells (43)(44)(45)(46)(47)(48)(49)(50)(51), lasers (52)(53)(54)(55), nonlinear optical devices (56)(57)(58)(59)(60)(61)(62), and biological imaging (44,(63)(64)(65)(66)]. A major milestone in this research field is to quantify the size-dependent properties of II-VI quantum dots and to map the transition from molecular to macroscopic crystal properties.…”

Facile synthesis of high-quality water-soluble N-acetyl-l-cysteine-capped Zn1−xCdxSe/ZnS core/shell quantum dots emitting in the violet–green spectral range

“…To date, various thiols, such as thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiolactic acid and so on have been used as the stabilizers to synthesize water-soluble quantum dots with violet-blue emission [13][14][15][16][17]. Unfortunately, they usually exhibited some unfavourable optical properties.…”

Photocatalytic degradation of E.coli membrane cell in the presence of ZnO nanowires

“…Fifty microliters of three groups of E. coli were mixed with 50 µL of L-Cysteine capped CdSe QDs [14] and incubate at 28 ℃ for 40 min, then washed twice by PBS, and resuspended in PBS (vide supra) for fluorescent imaging (Olympus BXT51RF, mercury lamp: U-LH100HG ), respectively.…”