Surabhi Nimbalkara | Searcharxiv

arXiv2026

Indirect Detection of Lactate Through Voltammetry Using Glassy Carbon Microelectrodes

Glassy carbon (GC) microelectrodes are increasingly being used for voltametric detection of electroactive neurotransmitters such as dopamine and serotonin. However, non-electroactive molecules including lactate, glutamate, and gamma-aminobutyric acid (GABA) cannot be directly detected using conventional voltammetry without surface functionalization. In this study, lactate oxidase was immobilized within a chitosan matrix on lithographically patterned GC microelectrodes to enable indirect detection of lactate via enzymatic generation of hydrogen peroxide, an electroactive byproduct. The resulting hydrogen peroxide was detected using fast-scan cyclic voltammetry (FSCV), enabling indirect in vitro detection of lactate at concentrations as low as 10 nM. The functionalized GC microelectrodes were integrated into a four channel array on a 1.6 cm flexible neural probe with potential for in vivo applications. Surface morphology and bonding interactions were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. FTIR analysis confirmed successful chitosan deposition through characteristic O-H, N-H, amide, and C-O stretching bands. Hydrogen peroxide detection was concentration-dependent, while lactate detection exhibited early saturation consistent with enzyme-limited kinetics. These results demonstrate a mechanically robust GC microelectrode platform for nanomolar-level indirect lactate sensing and provide insight into the reaction-diffusion coupling governing enzyme-based electrochemical detection.

physics.bio-ph↗

arXiv2023

Insights to Molecular and Bulk Mechanical Properties of Glassy Carbon Through Molecular Dynamics Simulation and Mechanical Tensile Testing

With increasing interest in the use of glassy carbon (GC) for a wide variety of application areas, the need for developing fundamental understanding of its mechanical properties has come to the forefront. Further, recent theoretical and modeling works that shed some light on the synthesis of GC through the process of pyrolysis of polymer precursors have highlighted the possibilities of a revisit to investigation of its mechanical properties at a fundamental level. While there are isolated reports on the experimental determination of its elastic modulus, insights into stress-strain behavior of GC material under tension and compression obtained through simulation, either at molecular level or for the bulk material is missing. This current study fills the gap at the molecular level and investigates the mechanical properties of GC using molecular dynamics (MD) simulations which model the atomistic level formation and breaking of bonds using bond-order based reactive force field formulations. The molecular model considered for this simulation has a characteristics 3D cagey structure of 5-, 6-, and 7-membered carbon rings and graphitic domain of a flat graphene-like structure. The GC molecular model was subjected to loading under varying strain rates (0.4/ns, 0.6/ns, 1.25/ns, and 2.5/ns) and varying temperatures (300 - 800 K) in each of the three axes x, y, and z. The simulation showed that GC molecule has distinct stress-strain curves under tension and compression. In tension, MD modeling predicted mean elastic modulus of 5.71 GPa for a single GC molecule with some dependency on strain rates and temperature, while in compression, the elastic modulus was also found to depend on the strain rates as well as temperature and was predicted to have a mean value of 35 GPa

cond-mat.mtrl-sci↗