Hebat-Allah S. Tohamy

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.

Sustainable upcycling of pomegranate peel and bagasse into P,N-doped carbon hybrids. Pickering nanoemulsions provide colorimetric and fluorometric detection of bacterial pH signatures.

The development of sustainable, smart food packaging materials that simultaneously provide antimicrobial protection and real-time monitoring of food quality is a critical frontier in food safety. This study reports the fabrication of a multifunctional amphiphilic emulgel designed for the detection of pathogen-induced metabolic pH changes in food systems. The system utilizes Pomegranate-derived nitrogen-doped quasi-spherical carbon dots (QS-CDs) as fluorescent nanoprobes and Rosemary Essential Oil (REO) as a natural antimicrobial agent, both encapsulated within a polyelectrolyte complex of chitosan and sugarcane bagasse-derived carboxymethyl cellulose (CMC). A low degree of substitution (DS = 0.4) was specifically engineered for the CMC to ensure an amphiphilic character, enabling nanocomposite complex stabilization of the REO droplets without synthetic surfactants. Structural characterization via Transmission Electron Microscopy (TEM) revealed well-dispersed QS-CDs (4.71–6.62 nm) and stable oil droplets (~605.49 nm) anchored within a zipped polymer network. Thermal analysis (TGA/DSC) using the Coats–Redfern model revealed a significant synergistic effect: the smart-emulgel exhibits a distinct two-stage degradation profile, with the high-temperature stage requiring an activation energy (E_a) of 95.19 kJ/mol, a substantial increase over the corresponding stage in the CD-emulgel baseline (18.69 kJ/mol). This enhanced stability is complemented by a slight increase in crystallinity (X_c from 0.11 to 0.14). While the smart-emulgel remains predominantly amorphous, this shift suggests that the integration of REO and QS-CDs into the polymer network promotes the formation of localized, more ordered domains, contributing to a more robust and structurally integrated matrix. The emulgel demonstrated a dual-mode optical response (colorimetric and fluorometric) sensitive to the metabolic byproducts (e.g., organic acids, amines, other alkaline compounds) produced by Escherichia coli and Staphylococcus aureus. These findings were corroborated by Density Functional Theory (DFT) calculations, which confirmed the thermodynamic stability and optimized electronic energy gaps for pH-responsive sensing. This research provides a green, high-performance platform for the real-time monitoring of food freshness and the prevention of foodborne illnesses.

The rapid expansion of synthetic azo dye pollution requires the development of multifunctional nanomaterials capable of simultaneous real-time monitoring and active chemical remediation. Herein, we report the one-pot, microwave-assisted hydrothermal synthesis of nitrogen-doped carbon nano-chains (N-CNCs) using Hibiscus sabdariffa botanical waste as a sustainable precursor. Transmission electron microscopy (TEM) confirmed the fabrication of an interconnected, one-dimensional (1D) beads-on-a-string morphology composed of monodisperse beads (2.08–2.96 nm). Selected area electron diffraction (SAED) verified a short-range turbostratic amorphous carbon framework. The synthesized N-CNCs function as a high-performance dual-mode environmental platform, serving as a high-contrast naked-eye pH sensor and an ultra-rapid catalyst for methyl orange (MO) degradation. Catalytic trials demonstrated a clean, systematic elimination of the chromophore within seconds (< 1 s) at environmental extremes, reaching degradation efficiencies of 79.30% (pH 3) and 74.67% (pH 12). Computational insights from Density Functional Theory (DFT) and Density of States (DOS) analysis decoded the underlying quantum logic, revealing a dramatic collapse of the frontier molecular orbital energy gap (E _g ) from 8.5416 eV in native N-CNCs to an ultra-reactive 0.8816 eV within the hybrid matrix. DOS spectra confirmed intense orbital crowding near the Fermi level, which drives instantaneous, non-radiative intramolecular electron transfer for irreversible azo-bond cleavage. This metal-free, circular-economy platform successfully bridges real-time optical tracking with high-capacity chemical remediation, offering a highly competitive blueprint for advanced wastewater treatment.

This study introduces highly sensitive, functionalized dialdehyde fullerene-like carbon nanostructures (DAFs) as a versatile platform for chemical sensing. The DAFs were synthesized through an effective functionalization strategy, confirmed by Fourier-Transform Infrared Spectroscopy (FTIR), which introduced key dialdehyde groups necessary for multi-modal detection. Transmission Electron Microscopy (TEM) validated a critical morphological evolution from small carbon dots (CDs) to larger, fullerene-shaped DAFs, providing a new electronic and structural foundation for sensing. The DAFs demonstrate dual sensing capabilities for both pH and non-polar organic vapors, specifically explosive cyclohexane (LEL ≈ 13000 ppm). The DAFs sensor's Limit of Detection (LOD) of 137.34 ppm is strategically justified by this hazard, as it provides an early, high-reliability safety warning significantly below the 10% LEL industrial safety threshold of 1300 ppm. Density Functional Theory (DFT) calculations elucidated the mechanism of gas detection, confirming that the interaction with non-polar cyclohexane fundamentally alters the electronic structure of the DAFs, causing the dipole moment (µ) to increase significantly from 5.060 Debye to 8.203 Debye, which underlies the observed fluorescence enhancement. Experimentally, the DAFs function as an effective pH probe, exhibiting a distinctive "turn-on" fluorescence response at alkaline pH 12 due to the deprotonation of surface functional groups. Crucially, the material operates as a simple, naked-eye visual sensor for cyclohexane, quantified by a clear shift in CIE chromaticity coordinates from (0.193, 0.422) to (0.209, 0.473) upon gas exposure. This work provides a deep, integrated theoretical and experimental understanding of functionalized carbon nanostructures for industrial safety and general environmental applications.

Pinewood sawdust waste was converted into nitrogen-doped carbon nanofibers for supercapacitors. The N-CNFs achieved a capacitance of 1280 F g ⁻¹ with 100% stability over 4000 cycles, offering a high-energy, sustainable storage solution for EVs.

This study presents the development of a smart packaging material utilizing garlic-derived nitrogen-doped carbon dots (CDs) integrated into a whey protein–starch (WP-S) emulsion. The research aimed to create a real-time, non-invasive biosensor capable of detecting microbial spoilage. The synthesized CDs demonstrated strong pH-sensitive photoluminescence, exhibiting distinct changes in CIE coordinates and fluorescence intensity in response to varying pH values. The WP-S-CDs emulsion was tested against E. coli, S. aureus, and C. albicans. The results showed that the composite film provided a clear colorimetric shift and fluorescence quenching, both of which are directly correlated with microbial metabolic activity. The physical and electronic properties of the composite were investigated to understand the sensing mechanism. Scanning electron microscopy (SEM) of the dried film revealed that the WP-S-CDs system formed a more porous structure with larger pore sizes (3.63–8.18 µm) compared to the control WP-S film (1.62–6.52 µm), which facilitated the rapid diffusion of microbial metabolites. Additionally, density functional theory (DFT) calculations demonstrated that the incorporation of CDs significantly enhanced the composite’s electronic properties by reducing its band gap and increasing its dipole moment, thereby heightening its reactivity and sensitivity to spoilage byproducts. In a practical application on apples, the WP-S-CDs coating produced a visible red spot, confirming its function as a dynamic sensor. The material also showed a dual-action antimicrobial effect, synergistically inhibiting C. albicans while exhibiting an antagonistic effect against bacteria. These findings validate the potential of the WP-S-CDs emulsion as a powerful, multi-faceted intelligent packaging system for food quality monitoring.