Neurospecific fabrication and toxicity assessment of a PNIPAM nanogel encapsulated with trans-tephrostachin for blood-brain-barrier permeability in zebrafish model

Abstract

Biocompatible Poly N-isopropyl acrylamide (PNIPAM) nanogels (NGs) were developed at 40–65 nm to deliver Trans-Tephrostachin (TT) in zebrafish brain. Neurospecific PNIPAM NGs are functionalized with polysorbate 80 (PS80) to overcome the Blood Brain Barrier (BBB). The TT loaded with NG (NG + TT) was confirmed in UV-spectroscopy and transmission electron microscopy (TEM) with 90% efficiency of controlled release at 37 °C. The neurospecificity of NG was confirmed in 144 h post fertilization (hpf) larvae with PS80 surface-treated rhodamine-B (Rh–B) conjugated NG and visualized in the CNS. Oral gavaging of TT loaded NG with PS80 surface treatment (NG + TT + PS80) was confirmed to cross the BBB in adult zebrafish at 37 °C. TT release was detected by RP-HPLC. LC₅₀ was determined as 250 μg/ml for NG, 172 μg/ml for NG + TT, and 0.9 μg/ml for TT at 96 hpf and confirmed the lesser toxicity in TT bound NG. Delays in growth and malformations were observed at concentrations above the 96 hpf-LC₅₀. The behavior outcomes were varied with phase - and concentration-dependent hypo- or hyperactivity. The altered expression of genes associated with Alzheimer's disease (AD) was found at 96 hpf of its LC₅₀ concentration. The expression of appa was significantly increased for TT and supporting the TT to bind NG without altering the AD genes. Thus the study suggests the biocompatible potential of PNIPAM and its neurospecific delivery to the brain.