Visiting research scientist, Northeastern University


Infection resistant, injectable cryogels suitable for drug delivery, regenerative therapy

Regenerative medicine has revolutionized medicine. But is associated with introduction of foreign material into the body, which is prone to attachment, colonization and infection by bacterial pathogens. There are many hospital borne pathogens which have developed resistance to existing antibiotics. If in case the patient catches such infection, it is likely pose severe threat. So in this scenario it is imperative to make the insertion material resistant to bacterial infection. In this direction, we are trying to attach HHC-36 to cryogel, HHC-36 is a kind of antimicrobial peptide which is strongly effective against strains of multidrug-resistant P. aeruginosa, methicillin-resistant Staphylococcus aureus, and a few other ‘superbugs. Hydrogels are a class of highly hydrated polymeric materials used in the biomedical field due to their unique properties such as high water content, softness, flexibility, and biocompatibility. Recently, we have developed mechanically robust and syringe-injectable biomimetic cryogels. These cryogels form a new class of polymeric hydrogels with unique properties including large and interconnected pores, mechanical robustness, and injectability with shape memory properties. We are trying out 2 complimentary approaches for attachment of HHC-36 to cryogel. First approach is to chemically attach the HHC-36 to cryogel so that initially it will kill the bacteria which come in direct contact and then over the time as cryogel degrades, HHC-36 will become free and will be released into the surrounding to kill the pathogens. The second approach is to physically entrap the HHC-36 withing cryogel such that it can diffuse out of the cryogel. Injectable antimicrobial cryogel scaffolds show great potential in tissue engineering as they can overcome two main challenges faced by gel implants, namely: biomaterial associated infections and suitable three-dimensional microarchitectural features for guided tissue regeneration and biointegration.


Mussel-Inspired Multifunctional Hydrogel Coating for Prevention of Infections and Enhanced Osteogenesis.

Abstract: Prevention of post-surgery infection and promotion of bio-integration are the key factors to achieve long-term success in orthopaedic implants. Localized delivery of antibiotics and bioactive molecules by the implant surface serves as a promising approach towards these goals. However, previously reported methods for surface functionalization of the titanium (Ti) alloy implants to load bioactive ingredients suffer from time-consuming complex processes and lack of long-term stability. Here, we present the design and characterization of an adhesive, osteoconductive, and antimicrobial hydrogel coating for Ti implants. To form the multifunctional hydrogels, a photocrosslinkable gelatin-based hydrogel was modified with catechol motifs to enhance adhesion to Ti surfaces and thus promote coating stability. To induce antimicrobial and osteoconductive properties, a short cationic antimicrobial peptide (AMP) and synthetic silicate nanoparticles (SNs) were introduced into the hydrogel formulation. The controlled release of AMP loaded in the hydrogel demonstrated excellent antimicrobial activity to prevent biofilm formation. Moreover, the addition of SNs to the hydrogel formulation showed enhanced osteogenesis when cultured with human mesenchymal stem cells, suggesting the potential to promote new bone formation in the surrounding tissues. Considering the unique features of our implant hydrogel coating including high adhesion, antimicrobial capability, and the ability to induce osteogenesis, it is believed that our design provides a useful alternative method for bone implant surface modification and functionalization.

Pub.: 01 Feb '17, Pinned: 03 Jul '17