Detection and monitoring of lactate and glucose levels in biological fluids and cell cultures are essential for understanding metabolic disorders. While electrochemical biosensors are commonly used, traditional enzymatic sensors face challenges related to stability, reproducibility, and cost. To address these limitations, we developed non-enzymatic sensors for lactate and glucose detection using nanostructured nickel oxide (NiO)–modified screen-printed carbon electrodes. The sensors were fabricated by drop-casting a NiO/Nafion/ethanol dispersion onto the working electrode, and their performance was evaluated using cyclic voltammetry and amperometry. Optimal sensitivity and linearity were achieved at a working potential of ∼0.5 V. The sensors exhibited linear responses for both lactate and glucose in the 0.1–5 mM range, with detection limits of 0.03 mM (lactate) and 0.025 mM (glucose), and sensitivities of 1.564 μA/mM (lactate) and 1.842 μA/mM (glucose) in 0.1 M NaOH–KCl electrolyte. To address glucose interference in lactate sensing, dual-sensing strategies were employed by varying Nafion concentration, applying differential potentials, or modifying the sensors with Prussian Blue to achieve selective detection. Validation against commercial lactate and glucose assay kits in cell culture medium showed good agreement, confirming the sensors’ accuracy. Finally, the sensor was integrated with a microfluidic chip, demonstrating its potential as a flow-through, enzyme-free metabolic sensor for future organ-on-a-chip applications.

Three-dimensional (3D) tumor spheroids are regarded as promising models for utilization as preclinical assessments of chemo-sensitivity. However, the creation of these tumor spheroids presents challenges, given that not all tumor cell lines are able to form consistent and regular spheroids. In this context, we have developed a novel layer-by-layer coating of cellulose nanofibril–polyelectrolyte bilayers for the generation of spheroids. This technique builds bilayers of cellulose nanofibrils and polyelectrolytes and is used here to coat two distinct 96-well plate types: nontreated/non-sterilized and Nunclon Delta. In this work, we optimized the protocol aimed at generating and characterizing spheroids on difficult-to-grow pancreatic tumor cell lines. Here, diverse parameters were explored, encompassing the bilayer count (five and ten) and multiple cell-seeding concentrations (10, 100, 200, 500, and 1000 cells per well), using four pancreatic tumor cell lines—KPCT, PANC-1, MiaPaCa-2, and CFPAC-I. The evaluation includes the quantification (number of spheroids, size, and morphology) and proliferation of the produced spheroids, as well as an assessment of their viability. Notably, our findings reveal a significant influence from both the number of bilayers and the plate type used on the successful formation of spheroids. The novel and simple layer-by-layer-based coating method has the potential to offer the large-scale production of spheroids across a spectrum of tumor cell lines.