Devine, Declan M.

In this study, we present a simple and effective process that integrates hydrogels with drugs + ceramics via physical crosslinks resulting in improved mechanical properties. These cryogels have the potential for controlled drug release and stimulus responsive behavior. The hydrogels were produced from polyvinyl alcohol (PVA) and polyacrylic acid by varying the molecular weight of the polymers, via freeze‐thawing technique. The cryogels were combined with two ceramics: (1) a combination of beta‐tricalcium phosphate, wollastonite, magnesium silicate and (2) titanium dioxide nanopowder. Theophylline, a model drug, was incorporated into the structure to analyze the drug release behavior. A layered structure was produced by adding both hydrogels + ceramics into a mold where a PVA dried film acted as a barrier and reinforcing structure. The results showed that the barrier integrated between both hydrogels by a physically crosslinking mechanism. This adhesion was demonstrated using Fourier‐transform infrared spectroscopy and scanning electron microscopy. Swelling of this composite showed the profile of drug release from both hydrogels + ceramics while simultaneously releasing the drug independently without diffusing via the opposite layer. Finally, mechanical properties were improved with the addition of the ceramics, which demonstrates the potential approach in terms of modification of weak hydrogel systems. POLYM. COMPOS., 39:E210–E220, 2018. © 2017 Society of Plastics Engineers

Polylactic acid (PLA) has a long history in medical applications. Reinforced PLA has the potential to be used in the medical applications that require high mechanical strength such as coronary stents and bone fixation devices. Halloysite nanotube (HNT) has received considerable attention recently due to its tubular structure, high aspect ratio, high mechanical strength, thermal stability, biocompatibility and sustained drug releasing properties. Halloysite has been investigated in compounding with many polymers. However, the research in compounding halloysite with biodegradable materials for use in biological applications is sparse. In this study various weight fractions of HNT was compounded with the biodegradable polymer PLA using a melt compounding method. Tensile test, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle test, scanning electron microscopy (SEM), void content and thermogravimetric analysis (TGA) were carried out to study the PLA/HNT composite. Tensile test results indicated that Young's modulus and stiffness of PLA were enhanced with the addition of HNT; FTIR spectra showed the interaction between the PLA and HNT; whereas contact angle measurements indicated that the wettability of the PLA/HNT composite was not affected by the addition of HNT. However, the thermal stability of PLA was adversely effected by the addition of HNT which may be related to the presence of voids between the polymer and matrix. Nevertheless, the reinforced PLA/HNT composite, which maintains the surface characteristics, may prove beneficial for use in biological applications. POLYM. COMPOS., 38:2166–2173, 2017. © 2015 Society of Plastics Engineers

Innovations on the field of smart hydrogels are now being held with loads of advantages. With recent progress, smart polymers can now be used on the market for specific target/objectives desired on medicine. However, the field of smart hydrogels has not been fully overviewed on the ground for drug delivery. In this study, a novel pH‐sensitive smart hydrogel for drug delivery was investigated. Polyvinyl‐alcohol (PVA) with polyacrylic acid (PAA) was blended adding synthetic hydroxyapatite (Hap) with freeze‐thawed cycles and its effects were studied in terms of mechanical strength, bioactivity, and drug release profile. Mechanical strength towards compression tests was decreased after addition of Hap and storage modulus (G') increased. Bioactivity was confirmed after 14 days on simulated body fluid (SBF). Improvement of swelling and gel fraction with the addition of Hap throughout the polymer matrix. Moreover, a study was performed with theophylline‐loaded samples for drug‐delivery studies. Copyright © 2015 John Wiley & Sons, Ltd.