Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites

Crosslinking of Pressure-Sensitive Adhesives with Polymer-Grafted Nanoparticles

Nanocomposite filler particles provide multiple routes to mechanically reinforce pressure-sensitive adhesives (PSAs), as their large surface area to volume ratios provide a means of effectively crosslinking multiple polymer chains. A major advancement could therefore be enabled by the design of a particle architecture that forms multiple physical and chemical interactions with the surrounding polymer matrix, while simultaneously ensuring particle dispersion and preventing particle aggregation. Understanding how such multivalent interactions between a nanoparticle crosslinking point and the PSA polymer affect material mechanical performance would provide both useful scientific knowledge on the mechanical structure-property relationships in polymer composites, as well as a new route to synthesizing useful PSA materials. Herein, we report the use of polymer-grafted nanoparticles (PGNPs) composed of poly(n-butyl acrylate-co-acrylic acid) chains grafted to SiO₂ nanoparticle (NP) surfaces to cohesively reinforce PSA films against shear stress without compromising their adhesive properties. The use of acrylic acid-decorated PGNPs allows for ionic crosslinking via metal salt coordination to be used in conjunction with physical entanglement, yielding 33% greater shear resistance and up to 3-fold longer holding times under static load. In addition, the effects of material parameters such as PGNP/crosslinker loading, polymer graft length, and core nanoparticle size on mechanical properties are also explored, providing insights into the use of PGNPs for the rational design of polymer composite-based PSAs.

Nanocomposite and bio-nanocomposite polymeric materials/membranes development in energy and medical sector: A review

Nanocomposite and bio-nanocomposite polymer materials/membranes have fascinated prominent attention in the energy as well as the medical sector. Their composites make them appropriate choices for various applications in the medical, energy and industrial sectors. Composite materials are subject of interest in the polymer industry. Different kinds of fillers, such as cellulose-based fillers, carbon black, clay nanomaterials, glass fibers, ceramic nanomaterial, carbon quantum dots, talc and many others have been incorporated into polymers to improve the quality of the final product. These results are dependent on a variety of factors; however, nanoparticle dispersion and distribution are major obstacles to fully using nanocomposites/bio-nanocomposites materials/membranes in various applications. This review examines the various nanocomposite and bio-nanocomposite materials applications in the energy and medical sector. The review also covers the variety of ways for increasing nanocomposite and bio-nanocomposite materials features, each with its own set of applications. Recent researches on composite materials have shown that polymeric nanocomposites and bio-nanocomposites are promising materials that have been intensively explored for many applications that include electronics, environmental remediation, energy, sensing (biosensor) and energy storage devices among other applications. In this review, we studied various nanocomposite and bio-nanocomposite materials, their controlling parameters to develop the product and examine their features and applications in the fields of energy and the medical sector.

Nanomaterials Application in Endodontics

In recent years, nanomaterials have become increasingly present in medicine, especially in dentistry. Their characteristics are proving to be very useful in clinical cases. Due to the intense research in the field of biomaterials and nanotechnology, the efficacy and possibilities of dental procedures have immensely expanded over the years. The nano size of materials allows them to exhibit properties not present in their larger-in-scale counterparts. The medical procedures in endodontics are time-consuming and mostly require several visits to be able to achieve the proper result. In this field of dentistry, there are still major issues about the removal of the mostly bacterial infection from the dental root canals. It has been confirmed that nanoparticles are much more efficient than traditional materials and appear to have superior properties when it comes to surface chemistry and bonding. Their unique antibacterial properties are also promising features in every medical procedure, especially in endodontics. High versatility of use of nanomaterials makes them a powerful tool in dental clinics, in a plethora of endodontic procedures, including pulp regeneration, drug delivery, root repair, disinfection, obturation and canal filling. This study focuses on summing up the current knowledge about the utility of nanomaterials in endodontics, their characteristics, advantages, disadvantages, and provides a number of reasons why research in this field should be continued.

Adhesion strength and viscoelastic properties of polydimethylsiloxane (PDMS) based elastomeric nanocomposites with embedded electrospun nanofibers

In the present study, the adhesive and viscoelastic properties of polydimethylsiloxane (PDMS) based nanocomposite pressure sensitive adhesives (PSAs) with embedded electrospun polyacrylonitrile (PAN) and polyvinyl alcohol (PVA) nanofibers as fillers were investigated. PDMS nanocomposite adhesive films using PAN and PVA nanofibers were synthesized by dispersing fillers in the matrix by a solvent mixing process. The adhesion strength and reusability of the prepared nanocomposite PSA films were measured using peel tests as the fraction of nanofibers in the polymer matrix is increased. The variations of the adhesive properties of the PSAs as function of the type and loading of filler were related to their rheological properties in terms of shear and elastic moduli. Although 3-fold enhancement of the adhesion strength was achieved with 0.5 wt% loading for both types (PAN and PVA) of nanocomposites as compared to elastic PDMS, the composite adhesive with PAN nanofibers can provide a superior balance of rheological properties, resulting in improved reusability over other PSAs. The differences in the adhesion and viscoelastic properties of the composite PSAs are attributed to the polymer chemistry, processability, and architecture of the electrospun nanofibers in the soft PDMS matrix.

Transdermal patches loaded with L-cysteine HCL as a strategy for protection from mobile phone emitting electromagnetic radiation hazards

Mobile phone usage has been increased in the last few years emitting electromagnetic radiation (EMR), which disturbs normal cellular processes via oxidative stress. L-cysteine, a glutathione precursor, prevents oxidative damage. Transdermal patches (TDPs) loaded with L-cysteine hydrochloride (L-CyS-HCL) were fabricated by dispersion of L-CyS-HCL 5% w/w and different concentrations of sorbitol as a plasticizer in room-temperature vulcanizable synthetic silicone matrices (RTV-Si). The effect of sorbitol on patch physicochemical parameters was assessed; in-vitro L-CyS-HCL release profiles and ex-vivo permeation were studied. Pharmacokinetic parameters of endogenous synthetized in-vivo glutathione, after receiving IV bolus dose of L-CyS-HCl and L-CyS-HCl-RTV-Si-TDPs were studied in rat model. The influence of L-CyS-HCL-RTV-Si-TDPs against damaging effects of mobile phone EMR on rats' blood and brain tissues was studied. The results revealed that patch plasticity, intensity reflections, surface porosity, L-CyS-HCL release rate and skin permeation increased with increasing sorbitol concentration. Pharmacokinetic profile for IV dose and L-CyS-HCl-RTV-Si-TDPs revealed that the L-CyS-HCl-RTV-Si-TDPs provided a sustained glutathione plasma concentration-time profile over entire patch application. High significant differences in biological parameters (blood and brain samples) were observed for radiated rats using the patch in study compared with positive control rats. Promising long-term strategy for protection against mobile phone hazards was obtained.

Processing polymer nanocomposites with natural additives for medical applications

The aim of this study is to analyze the effect of natural additive incorporation on processing nanocomposites and their effect on the functional characteristics of nanocomposites such as water uptake characteristics, drug adsorption and dissolution behaviors. Chitosan and montmorillonite were processed with olive oil and glycerin natural additives. In order to compare the processing results, the structure and the morphology of the polymer nanocomposites were examined by using infrared spectra, X-ray diffractograms and electron microscope images. Processing with nontoxic and healthful olive oil as a hydrophobizing agent overcame the high water uptake properties of the polymer nanocomposites and eliminated the use of other expensive chemicals. The nanocomposites without additives adsorbed the highest amounts of methylene blue at equilibrium. In vitamin B12 dissolution studies, not only the additives but also the reinforcement affected the results. Obviously, it can be seen that both the natural additive types and the reinforcement modification effects governed the drug adsorption and dissolution behaviors of the new tailored polymer nanocomposites. Moreover, the additives also improved the processing and handling abilities of these polymer nanocomposites. According to the results, these nanocomposites are promising candidates for medical applications like as a carrier for drug delivery and for skin treatment studies.

Review of Clay-Drug Hybrid Materials for Biomedical Applications: Administration Routes

Focus here is placed on the pharmaceutical and biomedical applications of novel clay-drug hybrid materials categorized by methods of administration. Clay minerals have been used for many years as pharmaceutical and medicinal ingredients for therapeutic purposes. A number of studies have attempted to explore clay-drug hybrid materials for biomedical applications with desired functions, such as sustained release, increased solubility, enhanced adsorption, mucoadhesion, biocompatibility, targeting, etc. The present review attempts not only to summarize the state-of-the-art of clay-drug hybrid materials and their advantages, depending on the methods of administration, but also to deal with challenges and future perspectives of clay mineral-based hybrids for biomedical applications.

Biomedical applications of cationic clay minerals

Different types of cationic clay minerals and their applications in various biological systems.

Comparative release studies of two cationic model drugs from different cellulose nanocrystal derivatives

Native cellulose nanocrystal (CNC), oxidized CNC (CNC-OX) and chitosan oligosaccharide grafted CNC (CNC-CSOS) were evaluated as potential drug delivery carriers for two model drug compounds, procaine hydrochloride (PrHy) and imipramine hydrochloride (IMI). The loading of PrHy and IMI was performed at pH 8 and 7, respectively. IMI displayed higher binding to CNC derivatives than PrHy. Drug selective membranes were prepared for each model drug and a drug selective electrode system was used to measure the drug concentration in the filtrate and release medium. Isothermal Titration Calorimetry (ITC) was used to elucidate the types of interactions between model drugs and CNC and its derivatives. The complexation between model drugs and CNC derivatives was confirmed by zeta potential and transmittance measurements. The binding and release of these drugs correlated with the nature and types of interactions that exist between the CNC and drug molecules.

Bioadhesion: a review of concepts and applications

Bioadhesion refers to the phenomenon where natural and synthetic materials adhere to biological surfaces. An understanding of the fundamental mechanisms that govern bioadhesion is of great interest for various researchers who aim to develop new biomaterials, therapies and technological applications such as biosensors. This review paper will first describe various examples of the manifestation of bioadhesion along with the underlying mechanisms. This will be followed by a discussion of some of the methods for the optimization of bioadhesion. Finally, nanoscale and macroscale characterization techniques for the efficacy of bioadhesion and the analysis of failure surfaces are described.

The use of nanocrystalline cellulose for the binding and controlled release of drugs

The objective of this work was to investigate the use of nanocrystalline cellulose (NCC) as a drug delivery excipient. NCC crystallites, prepared by an acid hydrolysis method, were shown to have nanoscopic dimensions and exhibit a high degree of crystallinity. These crystallites bound significant quantities of the water soluble, ionizable drugs tetratcycline and doxorubicin, which were released rapidly over a 1-day period. Cetyl trimethylammonium bromide (CTAB) was bound to the surface of NCC and increased the zeta potential in a concentration-dependent manner from -55 to 0 mV. NCC crystallites with CTAB-modified surfaces bound significant quantities of the hydrophobic anticancer drugs docetaxel, paclitaxel, and etoposide. These drugs were released in a controlled manner over a 2-day period. The NCC-CTAB complexes were found to bind to KU-7 cells, and evidence of cellular uptake was observed.

Cellulose-Based Bio- and Nanocomposites: A Review

Cellulose macro- and nanofibers have gained increasing attention due to the high strength and stiffness, biodegradability and renewability, and their production and application in development of composites. Application of cellulose nanofibers for the development of composites is a relatively new research area. Cellulose macro- and nanofibers can be used as reinforcement in composite materials because of enhanced mechanical, thermal, and biodegradation properties of composites. Cellulose fibers are hydrophilic in nature, so it becomes necessary to increase their surface roughness for the development of composites with enhanced properties. In the present paper, we have reviewed the surface modification of cellulose fibers by various methods. Processing methods, properties, and various applications of nanocellulose and cellulosic composites are also discussed in this paper.

Antimicrobial activities and cellular responses to natural silicate clays and derivatives modified by cationic alkylamine salts

Nanometer-scale silicate platelet (NSP) materials were previously developed by increasing the interlayer space and exfoliation of layered silicate clays such as montmorillonite and synthetic fluorinated mica by the process of polyamine exfoliation. In this study, the antibacterial activity and cytotoxicity of these nanometer-scale silicate clays were evaluated. The derivatives of NSP (NSP-S) which were modified by C18-fatty amine salts via ionic exchange association exhibited the highest antibacterial activity in the aqueous state among all clays. The high antibacterial activity, however, was accompanied by elevated cytotoxicity. The variations of cell surface markers (CD29 and CD44) and type I collagen expression of fibroblasts treated with the clays were measured to clarify the mechanism of the silicate-induced cytotoxicity. The signal transduction pathway involved the downregulation of extracellular-signal-regulated kinase (ERK), which appeared to participate in silicate-induced cytotoxicity. This study helped to understand the antibacterial potential of NSP and the interaction of natural and modified clays with cellular activities.