Smart-Phone-Assisted Optical Biosensors Based on Silk-Fibroin-Decorated Reduced Graphene Oxide Quantum Dots for Fluorescent Turn-On Recognition of l-Dopa

Abstract

Levodopa (l-dopa) is a gold standard neurological drug for symptomatic medication of Parkinson’s disease. The long-term use of l-dopa therapy frequently leads to l-dopa-induced dyskinesia and several other non-motor flocculants for fluctuating plasma concentration. To alleviate the adverse effect of dopamine replacement therapy, sensitive detection of l-dopa is still challenging. Therefore, this study presents a simple strategy to develop an inexpensive, easy-to-use, smartphone-based fluorescence turn-on sensory system based on the aggregation-induced emission enhancement phenomenon for instant low-level detection of l-dopa in biological samples. The sensor was fabricated using silk-fibroin-decorated reduced graphene oxide quantum dots, which exhibit a progressive increase of fluorescence intensity in the presence of l-dopa. By measuring the turn-on efficiency of the sensor in elevated concentrations of l-dopa, the limit of detection (LOD) was evaluated as 76.18 nM over a linear range of 0–35 μM. We have further designed a smartphone-based electronic device involving a 365 nm light emitting diode attached below the rare camera for capturing the change of fluorescent color of the solution during sensing. From these images, red, green, and blue values are analyzed using a mobile phone application, and the corresponding LOD was found to be 0.29 μM in a similar linear range of concentration. This simple, cost-effective, and rapid screening gadget is very demanding for on-spot detection of the analytes in remote areas where sophisticated instrumentation is not usually available.

Bio-conjugated carbon dots for the bimodal detection of prostate cancer biomarkers via sandwich fluorescence and electrochemical immunoassays

“…27 Furthermore, a paper-based sensing matrix integrated with smartphone-based measurement facilitates point-of-care analysis biosensors not only for monitoring and diagnosing cancer but also for other diseases. 28 In this work, PNP-modified paper was used to immobilize antibodies, followed by PSA and detection probe binding. Different concentrations (5, 10, 25, 50, 100, and 120 ng ml −1 ) of PSA standard were used to bind to the sensor surface.…”

Biomedical applications of graphene-based nanomaterials: recent progress, challenges, and prospects in highly sensitive biosensors

“…Analyzing the red, green, and blue values through a mobile app revealed a matching LOD of 0.29 M within a similar concentration range. This economical and swift screening technique, suitable for remote areas lacking sophisticated instrumentation, holds promise for on-the-spot analyte detection [ 99 ].…”

Chiral discrimination of l-DOPA vial/d-tryptophan decorated carbon quantum dots

“…The corresponding probe showed a linear response to l -DOPA in the range of 0–35 μM with an LOD value of 76.18 nM. 37 Therefore, understanding and addressing chiral discrimination based on CQDs is critical for the development and use of safe and effective pharmaceuticals. To the best of our knowledge, this study represents the first and only reported investigation of chiral CQDs that exhibit exceptional performance in the chiral detection of l -DOPA.…”