Polyelectrolyte-Coated Mesoporous Bioactive Glasses via Layer-by-Layer Deposition for Sustained Co-Delivery of Therapeutic Ions and Drugs

In the field of bone regeneration, considerable attention has been addressed towards the use of mesoporous bioactive glasses (MBGs), as multifunctional therapeutic platforms for advanced medical devices. In fact, their extremely high exposed surface area and pore volume allow to load and the release of several drugs, while their framework can be enriched with specific therapeutic ions allowing to boost the tissue regeneration. However, due to the open and easily accessible mesopore structure of MBG, the release of the incorporated therapeutic molecules shows an initial burst effect leading to unsuitable release kinetics. Hence, a still open challenge in the design of drug delivery systems based on MBGs is the control of their release behavior. In this work, Layer-by-layer (LbL) deposition of polyelectrolyte multi-layers was exploited as a powerful and versatile technique for coating the surface of Cu-substituted MBG nanoparticles with innovative multifunctional drug delivery systems for co-releasing of therapeutic copper ions (exerting pro-angiogenic and anti-bacterial effects) and an anti-inflammatory drug (ibuprofen). Two different routes were investigated: in the first strategy, chitosan and alginate were assembled by forming the multi-layered surface, and, successively, ibuprofen was loaded by incipient wetness impregnation, while in the second approach, alginate was replaced by ibuprofen, introduced as polyelectrolyte layer. Zeta-potential, TGA and FT-IR spectroscopy were measured after the addition of each polyelectrolyte layer, confirming the occurrence of the stepwise deposition. In addition, the in vitro bioactivity and the ability to modulate the release of the cargo were evaluated. The polyelectrolyte coated-MBGs were proved to retain the peculiar ability to induce hydroxyapatite formation after 7 days of soaking in Simulated Body Fluid. Both copper ions and ibuprofen were co-released over time, showing a sustained release profile up to 14 days and 24 h, respectively, with a significantly lower burst release compared to the bare MBG particles.

Regulation of the stability of kaolin dispersion in the salt media by acrylamide copolymers

As a result of the study of the effect of acrylamide copolymers on the stability of the kaolin salt dispersion, it was shown that the aggregation of solid phase particles and the deposition rate of flocs increases when polymers with different adsorption activity are alternately dosed to a disperse system. The adsorption limit, adsorption capacity and adsorption constant are at maximum for alternate adsorption of anionic polyelectrolyte on a cationic polyelectrolyte layer. High adsorption capacity and interaction energy of polymers with the surface and with each other leads to an improvement in flocculation and to the increase in the deposition rate of the kaolin-salt dispersion by 1.3–1.5 times.

Tripling the Reverse Electrodialysis Power Generation in Conical Nanochannels Utilizing Soft Surfaces

We theoretically investigate the feasibility of enhancing the reverse electrodialysis power generation in nanochannels by covering the surface with a polyelectrolyte layer (PEL). Along this line, two conical nanochannels are...