materials are typically developed at a critical length of under 100 nm. However, other phenomena, such as transparency and stable dispersion, can occasionally extend the upper limit, and the use of the prefix "nano" is accepted for dimensions smaller than 500 nm. [2] Two relevant factors differentiate nanomaterials from macroscopic materials: first, the quantum effect that can promote changes in physical properties, such as color and electrical conductivity, and second, the surface effect related to the increased surface area to volume ratio that favors physical and chemical interactions between atoms and the surrounding environment. [3] NPs are of the same order of magnitude as antibodies, membrane receptors, nucleic acids, proteins, and other biomolecules, thus representing a potential material to be used in medicine for imaging applications, diagnosis, therapies, or in medical devices. [4] The small size and large surface area of NPs facilitate their permeation through cell membranes and enhance their biological activity. [5] Microbial colonization of medical devices leads to the formation of microbial or fungal biofilms, which are complex assemblages of microbial cells associated with a surface and incorporated into an extracellular matrix. [6] Biofilms are critical clinical issues because they culminate in the pathogenesis of numerous bacterial infections that are difficult to treat and effectively eradicate with antibiotics. [7] Biofilm formation can occur in three stages: attachment, maturation, and dispersion. The attachment step can be further categorized in two-stage processes: initial reversible attachment and irreversible attachment, in which the attached biofilm can tolerate strong shear forces. [8] The bacteria deposition is mediated by sedimentation, Brownian motion, and hydrodynamic forces, whereas adhesion is governed by Van der Waals, acid-base, hydrophobic, and electrostatic interaction forces. [9] Attachment is the most crucial phase to prevent bacterial adhesion because the antimicrobial action becomes less effective after biofilm formation. [10] Medical devices commonly affected by microbial contamination and biofilm formation are catheters, probes, and wound dressings. Catheters are used in patients to administer fluids, blood products, and parenteral nutrition. [6] Most nosocomial infections in intensive care units (ICUs) are associated with the insertion and maintenance of central venous catheters Nanomaterials with antimicrobial activity are promising alternatives to overcome microbial resistance in medical devices. Catheters, probes, and wound dressings are among the medical devices mostly affected by microbial contamination and the formation of polymicrobial biofilms. Nanoparticles (NPs) derived from natural sources, such as chitosan nanoparticles (CsNPs), and metal-based nanoparticles, including silver nanoparticles (AgNPs), are receiving increased interest in nanomedicine. CsNPs have been widely explored as a coating material and antimicrobial agent. AgNPs have a strong antimicrobi...

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Chitosan is a polycationic polysaccharide with good health and nutritional benefits. This study investigated the effect of chitosan properties, such as, biopolymer structure, viscometric molar mass (Mv), and degree of deacetylation (DD), on the fat‐binding capacity between five chitosan preparations (different origins and characteristics) and three types of fat (soybean oil, margarine, and pork lard). The in vitro fat‐binding tests were performed with soybean oil under different pH to simulate the digestion process in the gastrointestinal tract, followed by tests at constant pH (duodenal pH = 6.8) with three types of fat. Shrimp shell nanochitosan had an average hydrodynamic diameter of 62 nm, while that of shrimp shell chitosan and commercial chitosans (CC1, CC2, and CC3) ranged between 1090 and 1405 nm (determined by DLS). The Mv of chitosan varied between 18 and 260 kDa, and the DD ranged from 62% to 92%. Chitosan with medium Mv and high DD presented better results of fat‐binding capacity in the duodenal pH with soybean oil. This study provides insights into the mechanisms of fat‐binding capacity and its correlation with physicochemical properties of chitosan, pH, and type of fat, allowing the production of chitosan‐based products with improved fat‐binding capacity for several applications.

Photovoltaic solar energy has been widely used as an alternative energy source. Composite materials combine the properties of organic polymers, including flexibility and easier processing, with those of inorganic compounds, such as thermal and chemical stability. These characteristics are advantageous to produce materials for organic solar cells. This work aimed to synthesize by casting method and characterize the structure, morphology, chemical, and thermal properties of composite membranes of polysulfone and chitosan (PSF/CS) incorporated with different masses of nickel-zinc ferrite nanoparticles (NZFN) and magnetite nanoparticles (MN). PSF/CS composite membranes incorporated with inorganic nanoparticles were uniform and transparent, evidencing a good dispersion of the nanoparticles and the homogeneity of the synthesized material. The addition of inorganic nanoparticles increases the stability and efficiency of organic substrates making them suitable for different applications in renewable energy systems, such as organic photovoltaic solar cells.

Biodegradable polyesters, such as the poly(lactic-co-glycolic acid) (PLGA), have been extensively used as a polymer matrix for entrapping a variety of active compounds. In this study, the physicochemical phenomena that control the mass transport mechanism of hydrophilic compounds released from PLGA microspheres were identified. This study aims to produce and characterize PLGA microspheres loaded with metformin hydrochloride (MH) and perform a case study using the literature data of PLGA microspheres loaded with fluorescein isothiocyanate-dextran (FITC-dextran). The MH is a low molecular weight compound that was easily and rapidly transported by diffusion mechanism through the microsphere pores. The FITC-dextran, as a high molecular weight compound, depended on the mechanism of polymer erosion and mesopore formation, with 18 days of duration, before its release by diffusion mass transfer. Values of the effective diffusion coefficient of MH and FITC-dextran, both in PLGA, were 2.4 x 10-13 and 5.3 x 10-18 m2 s-1, respectively, with a difference of five orders of magnitude attributed to the molecular weight of these hydrophilic compounds and the main mass transport that governed their release. This study provides important insights into the mechanisms of mass transfer and their correlation with the physicochemical properties of both hydrophilic compounds and the PLGA matrix, contributing to the development of biodegradable controlled delivery systems for a variety of applications in chemical, biotechnological, and pharmaceutical industries.