Interpenetrating Polymer Network Hydrogels Formed Using Antibiotics as a Dynamic Crosslinker for Treatment of Infected Wounds

Antibacterial hydrogels, particularly antibiotic-loaded hydrogels, are promising wound dressing materials for treatment of bacteria-infected wound. However, it is challenging to achieve sustained release of antibiotics from hydrogels through physical encapsulation of the antibiotics. Herein, an interpenetrating polymer network P(AA-co-HEMA)_Gen hydrogel is reported with double crosslinking formed by free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA), while using the antibiotic gentamicin (Gen) as the dynamic physical crosslinker. Gentamicin is incorporated into the hydrogel networks via electrostatic interaction between the carboxyl groups of poly(acrylic acid) and the amino groups of gentamicin, which leads to pH-responsive drug release and a significant increase in mechanical strength (i.e., elastic modulus, viscous modulus, and compressive modulus). More importantly, the hydrogels with optimal compositions demonstrate long-lasting antibacterial activity against both Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) over 28 d. The in vivo studies that are conducted in an S. aureus-infected full-thickness skin wound model demonstrate that the double crosslinking hydrogels loaded with gentamicin eliminate bacteria in the wounds more effectively and significantly accelerate wound healing as compared to 3M dressing and the control without any treatment. Taken together, this antibiotic-loaded interpenetrating polymer network hydrogel is potentially a promising wound dressing material for the treatment of bacteria-infected wound.

Swelling-strengthening hydrogels by embedding with deformable nanobarriers

Biological tissues, such as muscle, can increase their mechanical strength after swelling due to the existence of many biological membrane barriers that can regulate the transmembrane transport of water molecules and ions. Oppositely, typical synthetic materials show a swelling-weakening behavior, which always suffers from a sharp decline in mechanical strength after swelling, because of the dilution of the network. Here, we describe a swelling-strengthening phenomenon of polymer materials achieved by a bioinspired strategy. Liposomal membrane nanobarriers are covalently embedded in a crosslinked network to regulate transmembrane transport. After swelling, the stretched network deforms the liposomes and subsequently initiates the transmembrane diffusion of the encapsulated molecules that can trigger the formation of a new network from the preloaded precursor. Thanks to the tough nature of the double-network structure, the swelling-strengthening phenomenon is achieved to polymer hydrogels successfully. Swelling-triggered self-strengthening enables the development of various dynamic materials.

Hydrogel formulations for biologicals: current spotlight from a commercial perspective

Hydrogels are, from a commercial perspective especially because of their ease of production, attractive sustained-release systems for high potent immunoglobulins with short circulation half-lives. Hydrogel formulations can reduce the dosing frequency while maintaining therapeutically relevant drug concentrations locally as well as systemically. However, hydrogels have only limited loading capacities and release hydrophilic immunoglobulins typically within hours or days, whereas weeks or months would be more preferable. Despite an evident medical need, the call for novel depot formulations seems to go unheard. This special report explores sought-after hydrogel properties, discusses arguments for using established versus novel excipients and provides selected examples for hydrogel formulations of biologicals that have proceeded into clinical development.

Hydrogels: an interesting strategy for smart drug delivery

Hydrogels are novel delivery systems that have drawn much attention in the current pharmaceutical scenario. Of all the advantages, the most important is their versatility, which makes them optimal for any kind of molecule, adequate to be administered by any administration route and capable to modulate the desired release profile. Current research is managed to solve the limitations of this systems; mainly the low mechanical strength and lack of control of release in time and quantity, and the reversibility of the delivery. Several approaches such as the use of multi-stimuli-sensitive mechanisms, the enhancement of mechanical properties using chemical crosslinkers, development of polyelectrolyte complexes, the increment of interpenetrating networks or composite hydrogels are providing excellent results. These systems represent a promising alternative due to the countless possibilities to offer for modulating drug release.