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Small molecules with free thiol groups always show high binding affinity to quantum dots (QDs). However, it is still highly challenging to detect the binding capacity between thiol-containing molecules and QDs inside a capillary. To conquer this limitation, a capillary electrophoresis with fluorescence detection (CE-FL) based assay was proposed and established to investigate the binding capacity between QDs and a poly-thiolated peptide (ATTO 590-DDSSGGCCPGCC, ATTO-C4). Interestingly, the results showed that interval time had a great influence on QDs and ATTO-C4 self-assembly, which can be attributed to longer interval time benefitting the binding of QDs to ATTO-C4. The stability assays on ATTO-C4-QD assembly indicated that high concentration of imidazole or GSH had a high capability of competing with the bound ATTO-C4, evidenced by dramatically dropping of S /S ratio from 0.78 to 0.30 or 0.29. Therefore, all these results above suggested that this novel CE-FL based detection assay could be successfully applied to the binding studies between QDs and thiol-containing biomolecules.

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Resolving quantum dots and peptide assembly and disassembly using bending capillary electrophoresisDespite the numerous techniques developed for the studying nanoparticle and peptide interaction nowadays, sensitive and convenient assay in the process of flow, especially to simulate the self-assembly of quantum dots (QDs) and peptide inflow in blood vessels, still remains big challenges. Here, we report a novel assay for studying the self-assembly of QDs and peptide, based on CE using a bending capillary. We demonstrate that the semicircles numbers of the bending capillary affect the self-assembly kinetics of CdSe/ZnS QDs and ATTO-D 3 LVPRGSGP 9 G 2 H 6 peptide. Moreover, benefitting from this novel assay, the effect of the position on the self-assembly has also been realized. More importantly, we also demonstrate that this novel assay can be used for studying the stability of the QDspeptide complex inflow. We believe that our novel assay proposed in this work could be further used as a general strategy for the studying nanoparticle-biomolecule interaction or biomolecule-biomolecule interaction.

Multienzyme detection and monitoring enzyme activity in situ are significant for the disease to diagnose. This study aims to develop a quantum dots (QDs)‐based nanoprobe Cyanine5‐DDDLEVLFQFPGLVPRGSGGHHHHHH‐QDs (Cy5‐LEVLVP‐QD), which is able to detect two enzymes inside a bent capillary using CE. Cy5‐LEVLVP and QDs were allowed to bind with each other through metal affinity interaction and then injected the Cy5‐LEVLVP‐QD complex into a capillary with different bends, followed by related enzyme that can cleave the Cy5‐LEVLVP peptide. The fluorescence of Cy5 was excited by QDs due to Förster resonance energy transfer. By monitoring the peaks produced by the original Cy5‐LEVLVP‐QD complex and a significant fluorescence change, sensitive analysis of two different enzymes was conducted. Therefore, the novel approach of using capillaries with semicircular bends could prove particularly useful for enzyme investigating in disease.