RESUMEN
Alpha-synuclein oligomers play a crucial role in the early diagnosis of Parkinson's disease (PD). In this study, a mercaptoundecanoic acid (MUA)-capped gold nanorod (GNR)-coated and chitosan (CH)-immobilized fiber optic probe has shown considerable sensitivity of its detection. The proposed U-shaped fiber optic biosensor based on localized surface plasmon resonance (LSPR) was applied to detect α-syn oligomer (OA) biomarker. By analyzing OA concentrations, the biosensor achieved a limit of detection of (LOD) 11 pM within the concentration range of 10-100 pM and the sensitivity value was found as 502.69 Δλ/RIU. Upon analysis of the CV% (coefficient of variation) and accuracy/recovery values, it is revealed that the sensor successfully fulfilled the criteria for success, displaying accuracy/recovery values within the range of 80%-120% and CV% values below 20%. This sensor presents significant advantages, including high sensitivity, specificity, and ability to detect very low concentrations of OA. In conclusion, the suggested U-shaped fiber optic biosensor has the potential to be valuable in the early detection of PD from a clinical perspective.
RESUMEN
In this study, a facile one-pot solid-state synthesis method is developed to shed light on the metal-enhanced fluorescence (MEF) effect in carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) hybrid materials. This is one of the few studies on the solid-state synthesis of N-doped CQDs/gold hybrid nanomaterials. We have conducted various sets of experiments to reveal the role of individual reagents during the nucleation and growth of nanoparticles. We have demonstrated that the addition of a small amount of gold salt illustrates a paramount effect (103-fold) in photoluminescence intensity. This effect is ascribed to MEF, which is caused due to interactions between the excited-state fluorophores and the free surface electrons of metal nanoparticles. It is interesting to note that a further increase of gold yields fluorescence quenching due to a large number of formed AuNPs causing fluorescence resonance energy transfer. By adjusting the volume ratio of gold salt and CD precursors, it is possible to obtain the CQDs-AuNPs hybrid with the highest fluorescence, which produces extensive visible light under 460 nm excitation. Synthesized materials have been successfully used for imaging human dermal fibroblasts and A549 lung epithelial cells. The dose-dependent cytotoxicity studies reveal that the hybrid structures do not have cytotoxicity.