Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS).

In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel.

Continuous research in prominent fields such as biotechnology, biomedicine and nanopharmaceutics has brought the development of a widespread class of materials, and studies for mesoporous materials have been exponentially growing lately. The purpose of this review is to provide a useful guide for different materials, methods and configurations that have been reported in the last 5 years for the synthesis of spherical mesoporous silica particles (MSP), in the colloidal size range (1-1000 nm). MSP exhibit several limitations that must be overcome in order to enable their medical and clinical use. Surface modification of these particles will allow getting new promising characteristics of these materials, including better drug release control and biocompatibility improvement. These modified MSP could be potentially used in many biomedical applications, especially for drug delivery systems. Emphasis is made on the pore size, diameter and shape of the final particles since these parameters will establish key characteristics, i.e., drug delivery profile, loading capacity and efficiency. Graphical Abstract Spreading the use of mesoporous silica particles in biomedicine is possible by the improvement of its inner characteristics through surface modification. This may be done by chemical functionalization or by coating with macromolecular layers or brushes, thus creating novel responsive core-shell hybrid composites to be used as carriers for drug delivery applications.

Mesoporous silica nanoparticles (MSNs) are one of the most promising nanocarriers in biomedicine. Nonetheless, surface modification has been pointed out as a condition necessary for drug delivery applications, where stability and biocompatibility are extremely important for the vehicle performance. Likewise, zwitterionic polymers are outstanding candidates in biological fields, where poly(sulfobetaine methacrylate) (pSBMA) has been widely studied. These polymers, known as antifouling materials, are able to render a surface capacity to avoid protein adhesion. In this work, a core‐shell nanocarrier was created, where pSBMA was covalently grafted by atom transfer radical polymerization (ATRP) onto a previously functionalized MSN surface. Brush morphologies with different chain lengths ( , between 6500 and 32 300) and graft densities (σpSBMA, between 0.15 and 0.51 molecules of pSBMA per nm2 of MSN) were obtained. Protein adhesion resistance was evaluated with two proteins: fibronectin (FN) and bovine serum albumin (BSA). The best nanocarrier synthesized allowed a reduction of 96% of FN and 76% of BSA adhesion (compared with an adsorption of 100% assigned to the native material). Since the influence of the brush morphology is seldom studied or reported, this work aims to comprehend how the configuration of the polymer brushes affected their antifouling capacity, in order to use this pSBMA‐MSN product for biomedical applications, notably as a possible drug delivery nanocarrier. Future work will analyze the solution behavior of the zwitterionic brushes to evaluate variations of temperature and pH values as possible mechanisms of delivery.

Zwitterionic polymer brush grafting is considered as a serious strategy for surface modification on mesoporous silica nanoparticles (MSN), and a prominent alternative to polyethylene glycol (PEG) films for antifouling applications. In this study, the solution behavior of poly(sulfobetaine methacrylate) (pSBMA) polymer brushes grafted on MSN (95 ± 15 nm particle diameter, 2.8 nm pore size) was evaluated. The temperature-responsive layers increased their hydrodynamic diameter (dH), indicating a conformational change from a surface-collapsed state to a fully solvated brush.This development was clearly marked by a transition temperature, directly related to the molecular weight and theoretical length of the polymer chains. Variation of the dH with pH values was also studied and a zwitterionic range of 5-9 was stablished where the electric charges in the molecule were balanced. Additionally, zeta potential (ZP) values for all pSBMA-MSN products were also measured. A decreasing trend of ZP with pH and an isoelectric point around 5.5-6.5 was obtained for all dispersions.Furthermore, the influence of temperature was analyzed on ZP and a directly proportional correlation was found, with increasing rates of 0.50-0.87 %/°C. Finally, ZP variation with electrolyte concentration was determined and a range of 40-60 mM of NaCl concentration was established to reach an almost zero charge point for all nanoparticles. It was demonstrated that solution response of pSBMA-MSN products can be modulated by the temperature, pH and ionic concentration of the media. These behaviors could be used as controlled release mechanisms for the application of pSBMA-MSN as a carrier in biomedicine and nanophamaceutical fields in the future.