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BACKGROUND: Folic acid (FA), a synthetically produced compound analogous to vitamin B9, also referred to as vitamin folate, is an essential compound in human health and faces challenges in stability during food processing. This study explores the incorporation of FA into carboxymethylcellulose (CMC) nanofibers using electrospinning to enhance its stability. RESULTS: In this study, optimization of both electrospinning and solution parameters facilitated the fabrication of nanofibers. Furthermore, incorporating FA into CMC/polyethylene oxide (PEO) nanofibers resulted in thinner fibers, with an average diameter of 88 nm, characterized by a flat shape and smooth surface. Fourier transform infrared spectroscopic analysis demonstrated substantial hydrogen bonding interactions between FA and the polar groups present in CMC. This interaction contributed to an encapsulation efficiency of 94.5%, with a yield exceeding 87%. Thermal analysis highlighted mutual interference between CMC and PEO, with FA enhancing the thermal stability and reducing the melting temperatures and enthalpies of PEO, while also increasing the reaction heats of CMC. The encapsulated FA remained stable in acidic conditions, with only 6% degradation over 30 days, demonstrating the efficacy of CMC/PEO nanofibers in safeguarding FA against acidic environments. Moreover, the nanofibers provided a protective barrier against UV radiation, thereby preserving the stability of FA. CONCLUSION: This study emphasizes the efficacy of CMC/PEO nanofibers as a protective matrix against FA degradation. The findings indicate that this innovative approach could significantly diversify the applications of FA in food fortification, addressing concerns regarding its vulnerability to temperature and hydrolysis reactions during food processing. © 2024 Society of Chemical Industry.

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N-alkyl-substituted polyacrylamides exhibit a thermal coil-to-globule transition in aqueous solution driven by an increase in hydrophobic interactions with rising temperature. With the aim of understanding the role of N-alkyl substituents in the thermal transition, this study focuses on the molecular interactions underlying the phase transition of poly(N,N-diethylacrylamide-co-N-ethylacrylamide) random copolymers. Poly(N,N-diethylacrylamide) (PDEAm), poly(N-ethylacrylamide) (PNEAm), and their random copolymers were synthesized by free radical polymerization and their chemical structure characterized spectroscopically. It was found that the values of the cloud-point temperature increased with PNEAm content, and particle aggregation processes took place, increasing the negative charge density on their surface. The cloud-point temperature of each copolymer decreased with respect to the theoretical values calculated assuming an absence of interactions. It is attributed to the formation of intra- and interchain hydrogen bonding in aqueous solutions. These interactions favor the formation of more hydrophobic macromolecular segments, thereby promoting the cooperative nature of the transition. These results definitively reveal the dominant mechanism occurring during the phase transition in the aqueous solutions of these copolymers.

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Natural cyclodextrins (CDs) can be formed by 6, 7, or 8 glucose molecules (α-, ß-, and γ-, respectively) linked in a ring, creating a cone shape. Its interior has an affinity for hydrophobic molecules, while the exterior is hydrophilic and can interact with water molecules. This feature has been used to develop active packaging applied to food, interacting with the product or its environment to improve one or more aspects of its quality or safety. It also provides monitoring information when food is optimal for consumption, as intelligent packaging is essential for the consumer and the merchant. Therefore, this review will focus on discerning which packaging is most appropriate for each situation, solubility and toxicological considerations, characterization techniques, effect on the guest properties, and other aspects related to forming the inclusion complex with bioactive molecules applied to packaging.

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OBJECTIVE: To develop N-(levodopa) chitosan derivatives through click chemistry to study their effect in brain cells.Significance: This study presents a proof-of-concept that macromolecules such as N-(Levodopa) chitosan derivatives traverse brain cell membranes and induce biomedical functionalities. METHODS: Through click chemistry, we developed N-(levodopa) chitosan derivatives. They were physically and chemically characterized by FT-IR, 1H-NMR, TGA and Dynamic Light Scattering analyses. Solution and nanoparticles of N-(levodopa) chitosan derivatives were tested in primary cell cultures from the postnatal rat olfactory bulb, substantia nigra and corpus callosum. Ca2+ imaging and UPLC experiments were used to investigate if the biomaterial modulated the brain cell physiology. RESULTS: N-(levodopa) chitosan derivatives induced intracellular Ca2+ responses in primary cell cultures of the rat brain. UPLC experiments indicated that levodopa attached to chitosan was converted into dopamine by brain cells. CONCLUSION: The present study shows that N-(levodopa) chitosan may be useful to develop new treatment strategies, which could serve as molecular reservoirs of biomedical drugs to treat degenerative disorders of the nervous system.

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The spatiotemporal temperature distributions of NIR irradiated polypyrrole nanoparticles (PPN) were evaluated by varying PPN concentrations and the pH of suspensions. The PPN were synthesized by oxidative chemical polymerization, resulting in a hydrodynamic diameter of 98 ± 2 nm, which is maintained in the pH range of 4.2-10; while the zeta potential is significantly affected, decreasing from 20 ± 2 mV to -5 ± 1 mV at the same pH range. The temperature profiles of PPN suspensions were obtained using a NIR laser beam (1.5 W centered at 808 nm). These results were analyzed with a three-dimensional predictive unsteady-state heat transfer model that considers heat conduction, photothermal heating from laser irradiation, and heat generation due to the water absorption. The temperature profiles of PPN under laser irradiation are concentration-dependent, while the pH increase only induces a slight reduction in the temperature profiles. The model predicts a value of photothermal transduction efficiency (η) of 0.68 for the PPN. Furthermore, a linear dependency was found for the overall heat transfer coefficient (U) and η with the suspension temperature and pH, respectively. Finally, the model developed in this work could help identify the exposure time and concentration doses for different tissues and cells (pH-dependent) in photothermal applications.

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One of the main challenges facing materials science today is the synthesis of new biodegradable and biocompatible materials capable of improving existing ones. This work focused on the synthesis of new biomaterials from the bioconjugation of oleic acid with L-cysteine using carbodiimide. The resulting reaction leads to amide bonds between the carboxylic acid of oleic acid and the primary amine of L-cysteine. The formation of the bioconjugate was corroborated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance (NMR). In these techniques, the development of new materials with marked differences with the precursors was confirmed. Furthermore, NMR has elucidated a surfactant structure, with a hydrophilic part and a hydrophobic section. Ultraviolet-visible spectroscopy (UV-Vis) was used to determine the critical micellar concentration (CMC) of the bioconjugate. Subsequently, light diffraction (DLS) was used to analyze the size of the resulting self-assembled structures. Finally, transmission electron microscopy (TEM) was obtained, where the shape and size of the self-assembled structures were appreciated.

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The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized characteristics. In the present review, we summarize the latest methods for the modification and derivatization of chitin and chitosan under experimental conditions, which allow a control over the macromolecular architecture. This is because an understanding of the interdependence between chemical structure and properties is an important condition for proposing innovative materials. New advances in methods and strategies of functionalization such as the click chemistry approach, grafting onto copolymerization, coupling with cyclodextrins, and reactions in ionic liquids are discussed.

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A series of thermoresponsive copolymers based on chitosan-g-poly(N-vinylcaprolactam) were synthesized by amidation reaction using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride as coupling reagent. The effect of molecular architecture on the thermoresponsive properties of the graft copolymers solutions was studied by varying the chain length of the grafted poly(N-vinylcaprolactam), PVCL, (in the range from 4 to 26 kDa) and the spacing between grafted chains onto the chitosan backbone. The most interesting characteristic of these copolymers is their solubility in water at temperatures below their lower critical solution temperature (LCST). These solutions presented a LCST between 36 and 44 °C, which decreases with the spacing and length of grafted PVCL chains onto the chitosan backbone, in contrast with the limited decrease of the LCST of PVCL above a critical M¯n value around 18 kDa. This behavior offers tangible possibilities for the preparation and application of sensitive bioactive formulations and "smart" drug delivery systems.

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