Microwave promoted synthesis of smart superporous poly (dimethylaminoethyl methacrylate-co-acrylamide) hydrogels and study of Kamlet-Abboud-Taft polarity functions for obtained materials

Cross-linking of poly(dimethylaminoethyl methacrylate) by phytic acid: pH-responsive adsorbent for high-efficiency removal of cationic and anionic dyes

A new high-efficiency adsorbent for cationic and anionic dyes named PAGD was synthesized via polymerization of dimethylaminoethyl methacrylate by employing glycidyl-methacrylate-modified phytic acid as a cross-linker. The experiment demonstrated that PAGD is pH-sensitive, and the maximum adsorption capacities of anionic dye Reactive Red 24 (RR24) and cationic dye Fuchsin Basic (FB) were 1871.23 and 482.54 mg g⁻¹, respectively. To the best of our knowledge, there has been no previous report on a dye adsorbent possessing an adsorption capacity of over 465 mg g⁻¹ for RR24. The excellent adsorption abilities toward RR24 are due to the introduced phytic acid groups, which could promote protonation of tertiary amine groups under acid pH conditions. Moreover, PAGD is able to selectively remove RR24 in a mixed solution of cationic dye and RR24. The adsorption isotherms and kinetics of PAGD fit well with the Langmuir isotherm and pseudo-second-order kinetic model, respectively. These results imply that PAGD is a promising adsorbent for removal of both cationic and anionic dyes.

The adsorbent PADG based on phytic acid and DMAEMA was synthesized and tested, which is pH-sensitive and shows high adsorption capacities for anionic and cationic dyes.

Microwave-assisted synthesis of TEMPO-labeled hydrogels traceable with MRI

Polymer functionalization strategies have recently attracted considerable attention for several applications in biomaterials science. In particular, technological advancements in medical imaging have focused on the design of polymeric matrices to improve non-invasive approaches and diagnostic accuracy. In this scenario, the use of microwave irradiation of aqueous solutions containing appropriate combinations of polymers is gaining increasing interest in the synthesis of sterile hydrogels without using monomers, eliminating the need to remove unreacted species. In this study, we developed a method for the in situ fabrication of TEMPO-labeled hydrogels based on a one-pot microwave reaction that can then be tracked by magnetic resonance imaging (MRI) without using toxic compounds that could be hostile for the target tissue. Click chemistry was used to link TEMPO to the polymeric scaffold. In an in vivo model, the system was able to preserve its TEMPO paramagnetic activity up to 1 month after hydrogel injection, showing a clear detectable signal on T₁-weighted MRI with a longitudinal relaxivity value of 0.29 mM s^-1, comparable to a value of 0.31 mM s^-1 characteristic of TEMPO application. The uncleavable conjugation between the contrast agent and the polymeric scaffold is a leading point to record these results: the use of TEMPO only physically entrapped in the polymeric scaffold did not show MRI traceability even after few hours. Moreover, the use of TEMPO-labeled hydrogels can also help to reduce the number of animals sacrificed being a longitudinal non-invasive technique.

Microwave-Assisted Preparation of Hydrogel-Forming Microneedle Arrays for Transdermal Drug Delivery Applications

1A microwave (MW)-assisted crosslinking process to prepare hydrogel-forming microneedle (MN) arrays was evaluated. Conventionally, such MN arrays are prepared using processes that includes a thermal crosslinking step. Polymeric MN arrays were prepared using poly(methyl vinyl ether-alt-maleic acid) crosslinked by reaction with poly(ethylene glycol) over 24 h at 80 °C. Polymeric MN arrays were prepared to compare conventional process with the novel MW-assisted crosslinking method. Infrared spectroscopy was used to evaluate the crosslinking degree, evaluating the area of the carbonyl peaks (2000-1500 cm-1). It was shown that, by using the MW-assisted process, MN with a similar crosslinking degree to those prepared conventionally can be obtained in only 45 min. The effects of the crosslinking process on the properties of these materials were also evaluated. For this purpose swelling kinetics, mechanical characterisation, and insertion studies were performed. The results suggest that MN arrays prepared using the MW assisted process had equivalent properties to those prepared conventionally but can be produced 30 times faster. Finally, an in vitro caffeine permeation across excised porcine skin was performed using conventional and MW-prepared MN arrays. The release profiles obtained can be considered equivalent, delivering in both cases 3000-3500 μg of caffeine after 24 h.