Nano interface potential influences in CdTe quantum dots and biolabeling

Preparation of molecularly imprinted ratiometric fluorescence sensor for visual detection of tetrabromobisphenol A in water samples

A sensitive molecularly imprinted ratiometric fluorescence sensor was constructed for the first time to visually detect tetrabromobisphenol A (TBBPA). The blue fluorescent carbon quantum dots (CQDs) were coated with SiO₂ through the reverse microemulsion method to obtain a stable internal reference signal CQDs@SiO₂. The ratiometric fluorescence sensor was finally prepared using red fluorescent CdTe QDs as the response signal in the presence of CQDs@SiO₂. When the molecularly imprinted polymers were combined with TBBPA, the fluorescence of CdTe QDs (Ex = 365 nm, Em = 665 nm) was rapidly quenched, while that of CQDs (Ex = 365 nm, Em = 441 nm) remained stable, resulting in a noticeable fluorescence color change. Moreover, the fluorescence intensity ratio (I₆₆₅/I₄₄₁)₀/(I₆₆₅/I₄₄₁) of the sensor showed a linear response to TBBPA in the concentration range 0.1 to 10 μM with a low detection limit of 3.8 nM. The prepared sensor was successfully applied to detect TBBPA in water samples. The recoveries were in the range 98.2-103%, with relative standard deviations lower than 2.5%. Furthermore, a fluorescent test strip for visual monitoring of TBBPA was constructed to streamline the procedure. The excellent results demonstrate that the prepared test strip has a broad prospect for the offline detection of pollutants.

The cytotoxicity of core-shell or non-shell structure quantum dots and reflection on environmental friendly: A review

Quantum dots are widely applicated into bioindustry and research owing to its superior properties such as broad excitation spectra, narrow bandwidth emission spectra and high resistance to photo-bleaching. However, the toxicity of quantum dots should not be underestimated and aroused widespread concern. The surface properties and size of quantum dots are critical relevant properties on toxicity. Then, the core/shell structure becomes one common way to affect the activity of quantum dots such as enhance biocompatibility and stability. Except those toxicity it induced, the problem it brought into the environment such as the degradation of quantum dot similarly becomes a hot issue. This review initially took a brief scan of current research on the cytotoxicity of QDs and the mechanism behind that over the past five years. Mainly discussion concentrated on the diversity of structure on quantum dots whether played a key role on the cytotoxicty of quantum dots. It also discussed the role of different shells with metal or nonmetal cores and the influence on the environment.

Carbon quantum dots-embedded electrospun antimicrobial and fluorescent scaffold for reepithelialization in albino wistar rats

A prosthetic scaffold development using fluorescent nanofiber is reported for an enhanced reepithelialization in wistar albino rats. In this study, a novel approach was followed to construct the biocompatible fluorescent nanofiber that will be helpful to monitor the tissue regeneration process. Here, a multifunctional carbon quantum dots (CQDs)-embedded electrospun polyacrylonitrile (PAN) nanofiber was fabricated and characterized using standard laboratory techniques. The biodegradation ability was assessed by simulated body fluid thereby analyzing porosity and water absorption capacity of the material. The fluorescent scaffold was tested for cytotoxicity and antimicrobial activity using bacterial and fibroblast cells and fluorescent stability was analyzed by bioimaging of animal and bacterial cells. Tissue regeneration capability of the developed scaffold was evaluated using wistar albino rats. Unlike biomicking scaffolds, the CQDs-embedded PAN-based substrate has given dual support by enhancing reepithelialization without growth factors and acted as an antimicrobial agent to provide contamination free tissue regeneration. Scaffolds were examined by using histostaining techniques and scanning electron microscopy to observe the reepithelialization in the regenerated tissues. The novel approach for developing infection free soft tissue regeneration was found to be phenomenal in scaffold development.

Upconversion nanotubes with tunable fluorescence properties based on Gd2O2S:Ln3+ (Ln3+ = Yb3+, Er3+) and derivatives for photodynamic therapy

In this study, Gd2O2S:Ln3+ (Ln3+ = Yb3+, Er3+) upconversion nanotubes (UCNTs) were synthesised by using Gd(OH)3:Ln3+ (Ln3+ = Yb3+, Er3+) nanotubes as the template. The luminescent and biological properties of Gd2O2S:Ln3+ (Ln3+ = Yb3+, Er3+) UCNTs, along with photodynamic therapy (PDT) applications of the Gd2O2S:8%Yb3+,2%Er3+ UCNT-Ce6 (chlorin e6) nanocomposites, were systematically studied. The resultant UCNTs showed excellent biocompatibility with human retinal pigment cells (ARPE-19) even after a prolonged incubation time of 72 h, and could be used as luminescent probes. Microscopic imaging revealed that the UCNTs existed mainly in cytoplasm. PDT studies on the Gd2O2S:8%Yb3+,2%Er3+ UCNT-Ce6 nanocomposites indicate that the growth of the tumour (cell) could be inhibited dramatically when it was injected (incubated) with Gd2O2S:8%Yb3+,2%Er3+ UCNT-Ce6 nanocomposites under the irradiation of 980 nm laser.