Development of a smart polymer film based on hydrogen-bonded organic frameworks: stimuli-responsive and ammonia sensing

A multifunctional polyvinyl alcohol (PVA) film integrated with a Metronidazole.hydrogen-bonded organic framework (MET.HOF) encapsulating metronidazole was developed. The stability of MET.HOF is to temperature and pH-sensitive variations, leading to the controlled release of metronidazole under such conditions. Additionally, the incorporation of anthocyanin into the polymer matrix imparts the ability to detect ammonia, as anthocyanin exhibits color changes in response to pH fluctuations. Consequently, this film serves as a temperature/pH-responsive smart wound dressing. To assess the drug release behavior, the film's responsiveness was tested at different pH levels (5.5, 7.4, and 9) and temperatures (37 °C and 40 °C), conditions representative of wound environments. The results demonstrated that the polymer film effectively released metronidazole at temperatures above 37 °C and under alkaline pH, allowing for tailored drug delivery based on wound conditions. Anthocyanin functioned as a natural pH indicator, enabling the detection of ammonia produced at infected wound sites. The polymer's color change was quantitatively analyzed using RGB color detection software, with a minimum detectable concentration of 1.25 ± 0.07 mg L^-1. The film exhibited a contact angle of 58.8° ± 4.2° and a swelling degree of 240% ± 50%. Antibacterial tests revealed a zone of inhibition of 10 mm ± 1 at a concentration of 50 mg mL^-1, with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) both at 500 μg mL^-1. The polymer also demonstrated significant antioxidant activity, ranging from 85.90 to 97.00%. The study introduces a novel factor influencing crystal growth in hydrogen-bonded organic framework structures.