In this research, we conducted a systematic evaluation of the synthesis parameters of a multi-responsive core-shell nanocomposite (Fe₃O₄ nanoparticles coated by poly(N-isopropylacrylamide) (PNIPAM) in the presence of chitosan (CS) (Fe₃O₄@PNIPAM-CS). Scanning electron microscopy (SEM) was used to follow the size and morphology of the nanocomposite. The functionalization and the coating of Fe₃O₄ nanoparticles (Nps) were evaluated by the ζ-potential evolution and Fourier Transform infrared spectroscopy (FTIR). The nanocomposite exhibited a collapsed structure when the temperature was driven above the lower critical solution temperature (LCST), determined by dynamic light scattering (DLS). The LCST was successfully shifted from 33 to 39 °C, which opens the possibility of using it in physiological systems. A magnetometry test was performed to confirm the superparamagnetic behavior at room temperature. The obtained systems allow the possibility to control specific properties, such as particle size and morphology. Finally, we performed vincristine sulfate loading and release tests. Mathematical analysis reveals a two-stage structural-relaxation release model beyond the LCST. In contrast, a temperature of 25 °C promotes the diffusional release model. As a result, a more in-depth comprehension of the release kinetics was achieved. The synthesis and study of a magnetic core-shell nanoplatform offer a smart material as an alternative targeted release therapy due to its thermomagnetic properties.

In the present research, an orange extract (OE) was obtained and encapsulated in a zein matrix for its subsequent physicochemical characterization and evaluation of its antioxidant capacity. The OE consists of phenolic compounds and flavonoids extracted from orange peel (Citrus sinensis) by ultrasound-assisted extraction (UAE). The results obtained by dynamic light scattering (DLS) and scanning electron microscopy (SEM) indicated that zein nanoparticles with orange extract (NpZOE) presented a nanometric size and spherical shape, presenting a hydrodynamic diameter of 159.26 ± 5.96 nm. Furthermore, ζ-potential evolution and Fourier transform infrared spectroscopy (FTIR) techniques were used to evaluate the interaction between zein and OE. Regarding antioxidant activity, ABTS and DPPH assays indicated no significant differences at high concentrations of orange peel extract and NpZOE; however, NpZOE was more effective at low concentrations. Although this indicates that ultrasonication as an extraction method effectively obtains the phenolic compounds present in orange peels, the nanoprecipitation method under the conditions used allowed us to obtain particles in the nanometric range with positive ζ-potential. On the other hand, the antioxidant capacity analysis indicated a high antioxidant capacity of both OE and the NpZOE. This study presents the possibility of obtaining orange extracts by ultrasound and coupling them to zein-based nanoparticulate systems to be applied as biomedical materials functionalized with antioxidant substances of pharmaceutical utility.

A core-shell of colloidal metal-responsive polymer provides an innovative model in functional materials. These core-shell nanocomposites offer the possibility to control some properties, such as particle size, surface plasmon resonance and morphology. In this research, we demonstrate the successful synthesis and functionality of gold nanorods (GNR) coated with the polymers chitosan (Ch) and poly(N-isopropylacrylamide) (PNIPAM). The polymer coatings are performed using a two-step method. First, GNR were coated with a thiolated chitosan (GNR-Ch) by replacing hexadecyltrimethylammonium bromide with a chitosan thiomer. Structural modification of GNR-Ch was monitored by Fourier transform infrared spectroscopy. Then a second polymeric coating was done by in situ free radical polymerization of N-isopropylacrylamide (NIPAM) on GNR-Ch to obtain the nanocomposite GNR-Ch-PNIPAM. The nanocomposite average size was analyzed by dynamic light scattering. The evolution of ζ potentials during the coatings was measured using electrophoretic mobility. GNR-Ch-PNIPAM presented a collapsed structure when heated above the lower critical solution temperature. The particle size of GNR-Ch-PNIPAM was manipulated by changing the pH. Plasmonic properties were evaluated by UV-Vis spectroscopy. Results showed an important blue shift due to the PNIPAM coating thickness. Thermo- and pH-responsive properties of the nanocomposite GNR-Ch-PNIPAM could be used as a drug delivery system.

In this study, we performed a systematic evaluation of the synthesis parameters of a multiresponsive core–shell nanoplatform (Fe₃O₄ nanoparticles coated by poly(N-isopropylacrylamide). These nanocomposites allow the possibility of controlling specific properties, such as particle size and morphology. The polymer coating was performed by in-situ free-radical polymerization of N-isopropylacrylamide on Fe₃O₄ nanoparticles to obtain a nanocomposite with a core–shell structure. We monitored the size and morphology of the nanocomposite by scanning transmission electron microscopy. Electrophoretic mobility determined the evolution of ζ-potentials during coating. We assessed the functionalization of the Fe₃O₄ nanoparticles by Fourier-transform infrared spectroscopy and ultraviolet-visible spectroscopy. The core–shell systems exhibited a collapsed structure when heated above the lower critical solution temperature, which was determined by dynamic light scattering. Squid based vibrating sample magnetometer tests were performed to verify superparamagnetic behavior at room temperature. The platform was approved as biocompatible for the HeLa and MDA-MB-231 cell lines by MTT assays, and it shows the desired properties for potential use in localized and controlled drug delivery.

The interesting properties of stimuli-responsive polymers lead to a wide range of possibilities in design and engineering of functional material for the biomedical application. A systematic approach focused on the evaluation of the physical properties of multiresponse (pH and temperature) PNIPAM was reported in this work. The effect of three different molar ratios of poly(n-isopropylacrylamide): chitosan (1:49, 1:99 and 1:198) were evaluated and labeled correspondingly as PC ₁ F, PC ₂ F, and PC ₃ F. An increase in the lower critical solution temperature (LCST) of sample PC ₁ F (34°C) was observed by differential scanning calorimetry (DSC). The presence of low molecular weight chitosan (LMWC) full-interpenetrating polymer (Full-IPN) segments in poly(n-isopropylacrylamide) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The hydrogel’s water capture was analyzed by two models of swelling, the power law model and a model that considers the relaxation of polymeric chains of the hydrogel, finding good correlations with experimental data in both cases. Sample PC ₃ F resulted with higher swellability, increasing the weight of the hydrogel around seven times. Hydrogel pH-sensibility was confirmed placing the samples at different pH environments, with an apparent increase in swellability for acidic conditions, confirming the highest swellability for sample PC ₃ F, due to hydrogen bonds boosted by chitosan high molar ratio. Based on these results, the hydrogel obtained has potential as a thermo-pH triggered hydrogel in drug delivery applications.

This study investigates the synthesis and characterization of zein nanoparticles (ZNp) loaded with grape pomace extract (GPE) from Vitis vinifera L. for applications in controlled release and antioxidant delivery. Grape pomace, a byproduct of the winemaking industry, is rich in bioactive compounds, including phenols and flavonoids, which possess antioxidant properties. To overcome the limitations of these compounds, such as photosensitivity and thermal degradation, they were incorporated into zein nanoparticles using the antisolvent technique. The physicochemical properties of the ZNp-GPE system were thoroughly characterized, including size, morphology, ζ-potential, and total phenol content. Results showed high encapsulation efficiency (89–97%) and favorable loading capacities. Characterization techniques, such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS), confirmed that GPE was successfully incorporated into the nanoparticles, thereby enhancing their antioxidant properties. The encapsulation process did not significantly alter the spherical morphology of the nanoparticles, and loading GPE resulted in a decrease in particle size. Total phenol content analysis showed that the ZNp-GPE nanoparticles effectively retained these compounds, confirming their potential as efficient delivery systems for antioxidants. This approach not only provides a method for protecting and enhancing the bioavailability of natural antioxidants but also contributes to the valorization of agricultural waste, promoting sustainability in bio-based industries.