Self-crosslinkable complexes based on poly(ethylene glycol) (PEG), poly(itaconic acid) (PIA) and N-methylol acrylamide (NMA) as pharmaceutical hydrophilic matrices

Synthesis and Characterisation of Novel Temperature and pH Sensitive Physically Cross-Linked Poly (N-vinylcaprolactam-co-itaconic Acid) Hydrogels for Drug Delivery

Previous studies involving poly N-vinylcaprolactam (PNVCL) and itaconic acid (IA) have synthesised the hydrogels with the presence of a solvent and a crosslinker, producing chemically crosslinked hydrogel systems. In this study, however, temperature sensitive PNVCL was physically crosslinked with a pH-sensitive comonomer IA through ultraviolet (UV) free-radical polymerization, without the presence of a solvent, to produce hydrogels with dual sensitivity. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy indicated successful polymerisation of the hydrogels. The temperature and pH sensitivity of the hydrogels was investigated. The lower critical solution temperature (LCST) of the gels was determined using the UV spectrometry and it was found that the incorporation of IA decreased the LCST. Rheology was conducted to investigate the mechanical and viscoelastic properties of the hydrogels, with results indicating IA that enhances the mechanical properties of the gels. Swelling studies were carried out at ~20 °C and 37 °C in different buffer solutions simulating the gastrointestinal tract (pH 2.2 and pH 6.8). In acidic conditions, the gels showed gradual increase in swelling while remaining structurally intact. While in basic conditions, the gels had a burst in swelling and began to gradually degrade after 30 min. Results were similar for drug release studies. Acetaminophen was incorporated into the hydrogels. Drug dissolution studies were carried out at 37 °C in pH 2.2 and pH 6.8. It was found that <20% of acetaminophen was released from the gels in pH 2.2, whereas the maximum drug released at pH 6.8 was 74%. Cytotoxicity studies also demonstrated the hydrogels to be highly biocompatible. These results indicate that physically crosslinked P(NVCL-IA) gels possess dual pH and temperature sensitive properties, which may be beneficial for biomedical applications such as drug delivery.

Controlled drug delivery of ciprofloxacin from ultrasonic hydrogel

Ciprofloxacin is an antibacterial fluoroquinolone that stops the DNA synthesis, after penetration into the bacterial cells. This drug is applied in the curing of bacterial infections, as well as in antibiotics to treat urinary infections in women, infectious diarrhea and typhoid fever. The objective of the present work is to study controlled release of ciprofloxacin by hydrogel prepared by ultrasound. For this, first the swelling properties of hydrogel and then the absorption of drug were evaluated. The swollen hydrogel was dried in oven (50°C) and was ready for release experiments. During release, the loaded powder of the hydrogel was added to a buffer solution of pH 7.4, similar to human body condition. Then drug concentration was measured using a UV-visible (UV-Vis) spectrophotometer and a calibration curve. The results showed that the hydrogel is sensitive to pH, which makes it a good candidate for ciprofloxacin delivery in intestine. In addition, it was shown that the drug absorption is proportional with the swelling content of the hydrogel and the drug concentration in the loading process. The chemical structure and morphology of the hydrogels and loaded drug were characterized using Fourier transform infrared, UV-Vis, scanning electronic microscopy and thermal gravimetric analysis spectroscopy. According to the results presented here, acrylic-based hydrogels can be used in biomedical fields, especially for controlled drug release.