Pearl-necklace nano-chains from tomato peel lycopene carbon dots: Enhanced Colloidal stability, ph sensing, and antibacterial monitoring

Abstract Transforming industrial tomato peel waste (a dense matrix of lignocellulosic fibers and bioactive lycopene) into advanced protective functional nano-probes. Utilizing a one-pot microwave-assisted hydrothermal route to synthesize carbon dot-decorated nanosheets (N-TP-CDs), which were then evolved into interconnected 1D pearl-necklace nano-chains (PN-NCs) via strategic carboxymethylation (Mercerization Depth = 0.53). Transmission Electron Microscopy (TEM) confirmed a morphological shift to 1D networks of pearls (2.88–4.39 nm), while Density Functional Theory (DFT) calculations revealed a narrowed energy gap (E g = 3.3170 eV) and an increased dipole moment (36.39 Debye) for enhanced electronic sensitivity. Demonstrated superior colloidal stability, a naked-eye chromogenic response to pH fluctuations, dual-mode selective NIR fluorescence shifts, and near-total antimicrobial efficacy (99.99%±1% against S. aureus and 99.62 ± 2% against E. coli ). By merging real-time diagnostic visibility with a potent bacterial inhibition efficiency, this research offers a sustainable, high-performance tool for intelligent food packaging and environmental monitoring.