The agriculture and agri-food sectors produce substantial amounts of plant-based waste. This waste presents an identifiable research opportunity to develop methods for effectively eliminating and managing it in order to promote zero-waste and circular economies. Plant-based waste and by-products are acknowledged as valuable sources of bioactive compounds, including cellulose fibers. Direct application of these fibers in non-food sectors such as textiles can reduce the environmental impact of secondary raw materials. This review aims to provide an overview of novel concepts and modern technologies for efficiently utilizing plant-based waste and by-products from the agricultural and agro-industrial sectors to extract fibers for a variety of final applications, including the fashion industry. Two major routes are identified to produce cellulose fibers: the extraction and purification of natural cellulose fibers and the extraction and purification of cellulose pulp that is further processed into manmade cellulosic fibers. Scalability of experimental results at the laboratory or pilot level is a major barrier, so it is critical to develop closed-loop processes, apply standardization protocols, and conduct life cycle assessments and techno-economic analyses to facilitate large-scale implementation.

Novel V₂O₅ bifunctional photocatalysts were prepared following a wet chemical process with the addition of anionic or non-ionic surfactants into the precursor solution and further heating under reflux. Detailed characterization and investigation of the relevant light-matter interactions proved that surfactants addition had a strong impact on the morphology, while also affecting the crystallinity, the optoelectronic properties, and the surface chemistry of the novel photocatalysts. The most efficient photocatalyst (T80) was based on tween 80, a surface-active agent employed for the first time in the synthesis of vanadium oxide materials. T80 presented crystalline nature without structural defects, which are usually centers of e⁻ − h⁺ recombination. This material also exhibited small crystal size, high porosity, and short migration paths for the charge carriers, enabling their effective separation during photocatalysis. Under UV light illumination, T80 was capable to reduce hexavalent chromium to trivalent up to 70% and showed high yields in degrading methylene blue azo-dye and tetracycline antibiotic water pollutants. This remarkably high bifunctional performance defines T80 as a promising and capable photocatalytic material for both advanced oxidation and reduction processes (AOPs-ARPs).

Inflammation and oxidative stress are involved in cardiovascular diseases. Nitrogen monoxide participates in the regulation of endothelial processes. Thus, derivatives of classic nonsteroidal anti-inflammatory drugs (NSAIDs), trolox or cinnamic acids esterified with 2-(nitrooxy)ethanol were designed and studied. It was found that the nitrogen monoxide (NO) releasing activity was comparable to that of S-nitroso-N-acetylpenicillamine. The nitrooxy derivatives decreased potently lipid indices in the plasma of hyperlipidaemic rats (30–85%). All compounds presented increased anti-inflammatory activity in vivo, inhibiting carrageenan-induced rat paw oedema as high as 76%, up to six times higher than that of the parent acids. Lipoxygenase inhibitory activity was significant for most of them, although the parent molecules exerted a minor effect (IC₅₀ > 0.2 mM). Those compounds incorporating an antioxidant structure inhibited rat microsomal membrane lipid peroxidation strongly and possessed radical scavenging activity. These results indicated that the described compounds could act at different targets in multifactorial diseases, further limiting the possible adverse effects of drug combinations.

Every year, large amounts of shrimp waste are disposed of in the environment, causing serious environmental problems. The prospect of recycling shrimp waste helps to reduce waste and protect the environment. In this study, three different shrimp species were used, including Pleoticus muellieri, Litopeneus vanamei, and Parapenaeus longirostris, separated into shells (PLMUS, LIVAS, PALOS) and tails (PLMUT, LIVAT, PALOT), and transformed into novel carbonaceous materials. Their adsorption properties were investigated using different chemical compounds (MB, MR, phenol, astaxanthin) in aqueous means. The materials were characterized through FTIR, BET, and SEM–EDS analyses. According to the results, the carbonaceous adsorbents presented high adsorption percentage of MB and astaxanthin (>90%), and low adsorption percentage of phenol and MR, owing to the different bonds that were formed between the functional groups of the organic substances and the corresponding groups on the surface of the materials. The results of the FTIR analysis show the presence of C=C groups from the aromatic rings of the adsorbed MB and MR at 1636 cm⁻¹, the presence of O-H functional groups from the adsorbed phenols at 3330 cm⁻¹, and the presence of C=C or C=O groups at 1730 cm⁻¹ after the adsorption of astaxanthin. According to the BET analysis, the increase in the specific surface area follows the order: LIVAS > PLMUS > PALOT > PALOS > PLMUT > LIVAT. SEM–EDS analysis presented compact structures with the main elements of C (37–56%), O (25–35%), and Ca (12–23%) for all materials. Kinetic analysis showed that the experimental adsorption data of all the organic substances can be best described by the pseudo-second order model, indicating that chemisorption is the prevailing mechanism. Consequently, such methods promote the sustainable management and zero-waste fish farming practices, fostering the production of high-added value materials not only for decontamination purposes but also for the isolation of bioactive substances.

Non-toxic carbon-based hybrid nanomaterials based on carbon nanodisks were synthesized and assessed as novel antibacterial agents. Specifically, acid-treated carbon nanodisks (oxCNDs), as a safe alternative material to graphene oxide, interacted through covalent and non-covalent bonding with guanidinylated hyperbranched polyethyleneimine derivatives (GPEI5K and GPEI25K), affording the oxCNDs@GPEI5K and oxCNDs@GPEI25K hybrids. Their physico-chemical characterization confirmed the successful and homogenous attachment of GPEIs on the surface of oxCNDs, which, due to the presence of guanidinium groups, offered them improved aqueous stability. Moreover, the antibacterial activity of oxCNDs@GPEIs was evaluated against Gram-negative E. coli and Gram-positive S. aureus bacteria. It was found that both hybrids exhibited enhanced antibacterial activity, with oxCNDs@GPEI5K being more active than oxCNDs@GPEI25K. Their MIC and MBC values were found to be much lower than those of oxCNDs, revealing that the GPEI attachment endowed the hybrids with enhanced antibacterial properties. These improved properties were attributed to the polycationic character of the oxCNDs@GPEIs, which enables effective interaction with the bacterial cytoplasmic membrane and cell walls, leading to cell envelope damage, and eventually cell lysis. Finally, oxCNDs@GPEIs showed minimal cytotoxicity on mammalian cells, indicating that these hybrid nanomaterials have great potential to be used as safe and efficient antibacterial agents.