Aqueous synthesis of red fluorescent l-cysteine functionalized Cu2S quantum dots with potential application as an As(iii) aptasensor.

Water-stable Cu2S quantum dots were obtained by applying l-cysteine as a Cu(ii) to Cu(i) reducer and stabilizer in water and using an inert atmosphere at ambient temperature. The obtained quantum dots were characterized by STEM, XRD, FT-IR, UV-Vis, Raman, and fluorescence spectroscopy. The synthesis was optimized to achieve Cu2S quantum dots with an average diameter of about 9 nm that show red fluorescence emission. l-cysteine stabilization mediates crystallite growth, avoids aggregation of the quantum dots, and allows water solubility through polar functional groups, improving the fluorescence. The fluorometric test in the presence of the aptamer showed a shift in fluorescence intensity when an aliquot of As(iii) with a concentration of 100 pmol l-1 is incorporated because As(iii) and the used aptamer make a complex, leaving free the quantum dots and recovering their fluorescence response. The developed Cu2S quantum dots open possibilities for fluorescent detection of different analytes by simply changing aptamers according to the analyte to be detected.

Morphology Effect of Photoconverted Silver Nanoparticles on the Performance of Surface-Enhanced Raman Spectroscopy Substrates.

Nowadays, surface-enhanced Raman spectroscopy (SERS) substrates are of great interest for many researchers, aiming to fabricate substrates with high sensitivity and low fabrication costs. In this study, we photoconverted Ag nanoparticles by using a simple and affordable red-green-blue light-emitting diode photoreactor. The obtained dispersions were transformed into a paste of nanoparticles and used to fabricate SERS substrates by a simple drop-casting process under controlled humidity conditions. The performance of these substrates was tested using p-aminothiophenol as a Raman probe. The results indicate that the particle shape has an influence on the Raman intensities and substrate sensitivity, showing a significant enhancement as the number of faces and vertices in the particle increases.

Facile and rapid detection of respiratory syncytial virus using metallic nanoparticles.

BACKGROUND: Respiratory syncytial virus (RSV) causes severe respiratory infection in infants, children and elderly. Currently, there is no effective vaccine or RSV specific drug for the treatment. However, an antiviral drug ribavirin and palivizumab is prescribed along with symptomatic treatment. RSV detection is important to ensure appropriate treatment of children. Most commonly used detection methods for RSV are DFA, ELISA and Real-time PCR which are expensive and time consuming. Newer approach of plasmonic detection techniques like localized surface plasmon resonance (LSPR) spectroscopy using metallic nanomaterials has gained interest recently. The LSPR spectroscopy is simple and easy than the current biophysical detection techniques like surface-enhanced Raman scattering (SERS) and mass-spectroscopy. RESULTS: In this study, we utilized LSPR shifting as an RSV detection method by using an anti-RSV polyclonal antibody conjugated to metallic nanoparticles (Cu, Ag and Au). Nanoparticles were synthesized using alginate as a reducing and stabilizing agent. RSV dose and time dependent LSPR shifting was measured for all three metallic nanoparticles (non-functionalized and functionalized). Specificity of the functionalized nanoparticles for RSV was evaluated in the presence Pseudomonas aeruginosa and adenovirus. We found that functionalized copper nanoparticles were efficient in RSV detection. Functionalized copper and silver nanoparticles were specific for RSV, when tested in the presence of adenovirus and P. aeruginosa, respectively. Limit of detection and limit of quantification values reveal that functionalized copper nanoparticles are superior in comparison with silver and gold nanoparticles. CONCLUSIONS: The study demonstrates successful application of LSPR for RSV detection, and it provides an easy and inexpensive alternative method for the potential development of LSPR-based detection devices.

Highly luminescent PbS/ZnS nanoparticles synthesized by a microwave method.

Nanoparticles with PbS core of 12 nm and shell of approximately 3 nm were synthesized at PbS:ZnS ratios of 1.01:0.1 using Merca Ptopropionic Acid as stabilizing agent. PbS/ZnS nanoparticles present a dramatically increase of Photoluminescence intensity, confirming the confinement of the PbS core by increasing the Quantum Yield from 0.63 to 0.92 by the addition of the ZnS shell. In this case, the synthesis by microwave method allows obtaining nanoparticles with enhanced optical characteristics in shorter reaction time than those of nanoparticles synthesized by colloidal method.