Online electrophoretic nanoanalysis using miniaturized gel electrophoresis and thermal lens microscopy detection

Online thermal lens microscopy (TLM) coupled with gel electrophoresis (GE) can represent a powerful tool for separating and detecting a wide range of biomaterials. Unlike slab gel electrophoresis (SGE), the proposed method does not require prolonged procedure between separation and detection. In this work, we developed an online monitoring GE system to separate and detect nanosized materials. The design is based on a homemade and cost-effective miniaturized GE chip (MGEC) integrated with real-time TLM detection through microcontroller-based digitization board platform. To validate the feasibility and practicability of the proposed approach, we evaluated its separation capability via employing synthesized Fe₃O₄-Au core-shell nanoparticles (NPs) which served remarkably for the proof-of-concept. The optimum conditions for the separation process were achieved through optimization of the excitation power as 30 mW, detection position at 24 mm, the concentration of agarose gel 0.5 % w/v, and 37.5 V/cm as the effective electric field strength. The findings showed that two populations of Fe₃O₄-Au, core-shell, and uncapped Fe₃O₄ NPs, were effectively separated in less than eleven minutes, demonstrating rapid assessment of the nanomaterial production quality. Moreover, other characterization techniques such as HRTEM and EDX were employed to confirm the presence of the two dissimilar kinds of NPs separated using MGEC-TLM. The sensitivity of the method was demonstrated by determining the limit of detection (23 pM) for 10 nm AuNPs. It is envisaged that our presented system enables rapid, economical, low volume of reagents consumption and high potential analysis for quality test in various bioanalytical and nanotechnological applications.