PEGylated Platinum Nanoparticles: A Comprehensive Study of Their Analgesic and Anti-Inflammatory Effects

Pain and inflammation are common symptoms of a majority of the diseases. Chronic pain and inflammation, as well as related dreadful disorders, remain difficult to control due to a lack of safe and effective medications. In this work, biocompatible platinum nanoparticles with significant analgesic and anti-inflammatory action were synthesized through a wet chemical method using polyethylene glycol-400 as a capping agent and sodium borohydride as a reducing agent. The average particle size of these Pt nanospheres was determined to be 3.26 nm using TEM analysis, and X-ray diffraction confirmed their face-centered cubic crystalline structure. Fourier transform infrared and UV-visible spectroscopy confirm that Pt-NPs are coated with the PEG-400 molecule. The significantly negative zeta potential value (-26.8 mV) indicates the stability of the produced nanoparticles. In vitro cytotoxicity studies on normal cell lines show nontoxic behavior with over 96% cell viability at 100 μg/mL of the test sample. In vitro assays of inhibition of protein denaturation and DPPH free radical scavenging elucidated the anti-inflammatory and antioxidant properties of PEGylated Pt NPs with promising EC₅₀ values 57.99 and 9.324 μg/mL, respectively. In vivo animal trials confirmed that PEG-capped Pt-NPs are more effective than conventional medicines. The in vivo hot plate assay for the analgesic study shows a maximum response time of 14.5 ± 1.22 s (92.54% analgesia) at a dosage of 50 mg/kg and 13.8 ± 0.71 s (86.05% analgesia) at a dosage of 25 mg/kg after 180 and 240 min of administration, respectively. In the rat paw edema model for anti-inflammatory activity, the PEG-capped Pt NPs exhibit significant inhibitory action, with the maximum percentage of edema inhibition at a dosage of 50 mg/kg identical to that of the aspirin-based standard medication administered at a higher dosage of 100 mg/kg, resulting in 42% inhibition, suggesting a versatile solution for inflammation and persistent pain.