Dipankar Chattopadhyay

Chemical recycling of polyethylene terephthalate (PET) waste through glycolysis has emerged as an attractive strategy for producing value-added polymeric materials. However, conventional PET-derived unsaturated polyester resins (UPRs) often suffer from reduced optical transparency owing to structural heterogeneity, increased crystallinity, and side reactions that occur during depolymerization and repolymerization processes. Although transparent recycled polyesters can be obtained using specialty monomers such as 1,4-cyclohexanedimethanol (CHDM) and isosorbide, their high cost limits large-scale industrial implementation. In this work, a cost-effective approach was developed for the synthesis of transparent UPRs from waste PET. PET waste was glycolyzed for different reaction times (0.5 and 3 h) to produce hydroxyl-terminated oligomers, which were subsequently repolymerized and converted into unsaturated polyester resin. The influence of depolymerization duration on molecular structure, morphology, transparency, thermal stability, and processing characteristics was systematically investigated using FTIR, NMR, GPC, SEM, UV–vis spectroscopy, XRD, TGA, and DSC analyses. GPC results demonstrated successful depolymerization followed by molecular-weight recovery after polyesterification, while FTIR confirmed the incorporation of maleate unsaturation into the polymer backbone. XRD analysis revealed the predominantly amorphous nature of the synthesized resins, while UV–vis spectroscopy showed exceptionally high optical transparency, with transmittance values exceeding 99% at 550 nm. The cured resins also exhibited suitable viscosity, gel time, hardness, and heat distortion temperature for practical applications. The combined use of sterically hindered neopentyl glycol (NPG) and meta-substituted isophthalic acid (IPA) effectively suppressed crystallization and preserved optical clarity, enabling the production of highly transparent recycled UPRs without the use of expensive specialty monomers. This study demonstrates a sustainable and economically viable route for converting PET waste into transparent, high-performance polyester resins for coating, composite, and decorative applications.

An ICT-based fluorescent probe, DMABT-NH2, was synthesized and incorporated into a nanofiber platform for the discriminative detection of phosgene and triphosgene with a ratiometric dual-channel fluorescence signal and colorimetric responses.

Recycling nylon helps reduce plastic pollution, conserve energy and save fossil fuel. This study presents a recycling‐based approach for developing high‐performance composites by reinforcing a virgin Nylon 66 (N66) matrix with electrospun nanofiber mats fabricated from recycled Nylon 66 (RN66) cable ties containing 0.5–5 wt.% graphene oxide (GO). Compression‐molded composites with different nanofiber orientations were fabricated and characterized using FTIR, EDS, SEM, DSC, TGA, and ASTM‐standard mechanical testing. Among the investigated compositions, the cross‐ply composite containing 2 wt.% GO exhibited the highest overall mechanical performance, with 31.5% higher flexural strength, 82.7% higher Izod impact strength, and 90.4% higher Charpy impact strength than neat N66, while also showing improved ductility. The cross‐ply composite containing 5 wt.% GO demonstrated the highest compressive strength (98.5 MPa, 35.9% higher than neat N66) and enhanced thermal stability, with the degradation onset temperature increasing from 365°C for neat N66 to 398°C. These results show that GO‐reinforced recycled Nylon 66 nanofibers enhance mechanical and thermal performance while valorizing post‐industrial nylon waste, offering a promising platform for lightweight engineering applications.

Clinical oncology faces a critical technological bottleneck driven by the rapid emergence of therapy-resistant tumors. Melanoma, in particular, remains a highly aggressive malignancy with pronounced metastatic potential and poor responsiveness to traditional therapy, signify the demand for advanced therapeutic strategies. Herein, we report a multifunctional nanoplatform integrating ternary layered double hydroxides (LDHs) with an injectable hydrogel system for localized and controlled melanoma therapy. The engineered trimetallic Cu–Zn–Fe LDHs (CZF) exhibit tunable physicochemical properties, enabling efficient drug intercalation, enhanced structural stability, and stimuli-responsive release within the tumor microenvironment. Doxorubicin (Dox) loaded LDHs (CZF@Dox) demonstrate high loading efficiency and sustained release, minimizing premature leakage and systemic toxicity. Computational insights from molecular dynamics and machine learning-assisted modeling reveal optimized host–guest interactions for improved delivery performance. In vitro studies confirm excellent biocompatibility toward normal 3T3-L1 cells (∼10% cell death at 20 μg/mL, 72 h), alongside significant cytotoxicity against B16F10 and SiHa cancer cells (∼80–85% cell death at the same conditions). In vivo evaluation further demonstrates effective tumor suppression with prolonged dosing intervals (96 h). Overall, this platform offers a predictive, minimally invasive, and efficient strategy for next-generation melanoma therapy.

Si is a multifaceted element in combating abiotic stress that mediated heavy metal detoxification via immobilisation, co-precipitation and ion-exchange. Phytoliths- are naturally occurring form of biogenic silica that held protective barrier in plant defence. In this study, phytoliths from three wild fern pinnae were extracted by modifying the established dry-ashing method for adsorption of Cr VI. Characterisation techniques, such as PZC, B-E-T analysis, FTIR, SEM-EDAX, UV-VIS spectroscopy, are employed to evaluate the characteristics of the sorbent. Sorption studies, kinetics, isotherms, and thermodynamic studies suggest chemisorption-driven metal uptake in the optimal setup. Biogenic silica immersed in Organic matrix were evaluated for XPS study. Predominance of Cr III (576.3–576.8eV of Cr2p3/2) verified post-adsorption changes in oxidation states. Aligning spectral analyses from XPS with FTIR peaks indicate the role of phenolic/carboxylic groups in electron-transfer-mediated reduction process, consistent with recent observation. Following, LC/ESI-MS profile analysis of the ethyl acetate fraction from crude was utilised to screen potent phenolic groups. Further a control set of experiments were established for the confirmation of reduction of Cr (VI) through the metabolites extracted in Ethyl acetate. From ESI/MS m/z ratio it is assumed that Lunularic acid may be the key electron donor responsible for reduction to Cr (III).Christella dentata bio-silica exhibited highest Cr VI adsorption capacity (Qmax = 9.68 mg g⁻¹).This research explores a novel investigation pathway into the function of fern-derived endogenous biogenic silica, associated with residual organic matrix, in the concurrent adsorption and reduction of hazardous Cr (VI) to its non-toxic Cr (III) form.

Despite extensive efforts toward photocatalytic degradation of organic dye pollutants, the fundamental reaction mechanisms remain unclear. In this research, we synthesized a SnS2/RGO composite with different mass ratios and systematically investigated it as a multifunctional photo and electrocatalyst. Among the prepared samples, the SnS2/RGO composite with a mass ratio of 1:2 exhibited superior photo and electrocatalytic performance. The enhanced activity is attributed to its reduced band gap and elevated Urbach energy, which promote extended solar-light absorption, efficient photogenerated charge carrier generation, and suppressed electron−hole recombination. As a result, the optimized SnS2/RGO (1:2) composite achieved a methylene blue degradation efficiency of 93.75% under visible-light irradiation. In addition, it demonstrated excellent electrocatalytic performance, delivering a hydrogen evolution reaction overpotential of 420 mV with a Tafel slope of 108 mV dec−1, along with an oxygen evolution reaction overpotential of 250 mV and a Tafel slope of 165 mV dec−1. Radical trapping experiments revealed that majorly hydroxyl radicals and minorly photogenerated holes are the reactive species responsible for dye degradation. Further, low solution resistance and charge-transfer resistances of the optimized composite were confirmed through electrochemical impedance spectroscopy analysis, indicating enhanced charge transport kinetics. Overall, our findings highlight the SnS2/RGO catalyst as a promising nanostructured catalysts for integrated environmental remediation and sustainable energy conversion applications.