Development, Characterisation and Neuroprotective Effects of Polymer-Drug Conjugate Nano-Polyplex: Working Towards a Multi-Target Treatment for Neurodegenerative Diseases

Abstract

Neurodegenerative diseases (NDs) are complex, multifaceted conditions that require novel, multi-targeted therapeutic approaches. This study aimed to develop a multifunctional polymer-drug conjugate (PDC) by employing a novel strategy of utilizing PDC-based nano-polyplexes as a multi-target treatment for NDs. The nano-polyplex (N5NM15) was formulated by combining polyallylamine hydrochloride-vanillin (NM15) and polyacrylic acid-naphthalimidohexylamine (N5) conjugates. Antioxidant capacity was measured via ORAC assay, and cholinesterase inhibition was evaluated using Ellman’s assay. Cytotoxicity, neuroprotective effects, and anti-inflammatory activity were tested in undifferentiated SH-SY5Y and BV-2 cells via MTT assay. Amyloid-beta aggregation was assessed using Thioflavin T assay and TEM imaging in a cell-free system. The results demonstrated that N5NM15 resulted in uniform nanoparticles with an average size of 30.5±7.9 nm, confirmed via Cryo-TEM. Cytotoxicity studies indicated high biocompatibility with SH-SY5Y cells (viability >90%) and moderate toxicity in BV-2 cells (viability 75%, p ≤ 0.001). Furthermore, N5NM15 demonstrated significantly enhanced in vitro antioxidant activity (p ≤ 0.001, after adjustment) and cholinesterase inhibition (p ≤ 0.0001 for AChE and p ≤ 0.01 for BuChE, after adjustment) compared to starting materials. N5NM15 also protected SH-SY5Y cells from hydrogen peroxide-induced oxidative stress (p ≤ 0.0001), reduced lipopolysaccharide-induced inflammation in BV-2 cells (p ≤ 0.05), inhibited BuChE activity in SH-SY5Y cells (p ≤ 0.01), and reduced amyloid-beta aggregation (p ≤ 0.01). Notably, polyacrylic acid demonstrated protective and anti-inflammatory effects in both cell lines (p ≤ 0.0001) and inhibited amyloid-beta aggregation (P ≤ 0.001). These findings suggest the potential use of N5NM15 and polyacrylic acid as treatment options for NDs.