Experimental investigations and DFT insights of atmospheric DBD plasma-induced surface modifications in curcumin-loaded PVA and chitosan films for bio-medical applications.

Polymer films are extensively used in biomedical applications, but their limited surface properties often restrict their functional performance. Non-thermal plasma treatment offers a clean and efficient strategy to modify the surface characteristics without altering the material's bulk properties. In this work, Cur/PVA and Cur/Ch films were surface-modified using Dielectric Barrier Discharge (DBD) plasma at 25 kV with argon as discharge gas. Experimental characterizations confirmed significant alterations in the surface properties after plasma treatment. Among the samples, plasma-treated Cur/Ch PT15 films exhibited better antibacterial activity against E. coli with an inhibition zone of 16 ± 0.3 mm and demonstrated a reduced drug release rate of 35.3 ± 2.3 %, indicating sustained release behavior. To understand the molecular mechanisms behind these enhancements, Density Functional Theory (DFT) calculations were performed. The plasma-treated Cur/Ch complex showed the lowest energy gap of 2.30 eV and the highest dipole moment of 8.09 Debye, indicating enhanced reactivity, polarity and stronger intermolecular interactions. The theoretical results correlated well with the experimental observations, confirming that plasma treatment induces favorable electronic modifications that contribute to improved antibacterial efficacy and drug retention. Overall, this study demonstrates the potential of plasma-modified Cur/Ch films as promising candidates for biomedical applications such as antibacterial applications and sustained drug delivery systems.