# Linear Polyethyleneimine-Coated Gold Nanoparticles as a Platform for Central Nervous System Targeting

## TL;DR

Researchers developed gold nanoparticles coated with polyethyleneimine that can potentially deliver drugs to the brain, showing biocompatibility and the ability to cross the blood-brain barrier.

## Contribution

A new method to create biocompatible, brain-targeted gold nanoparticles using linear polyethyleneimine as a reducing and stabilizing agent.

## Key findings

- GNP@PEI nanoparticles were monodisperse and had an average diameter of 50 nm.
- The nanoparticles showed high biocompatibility in neural cultures and cell lines.
- In vivo studies showed detectable levels of gold in the brain after administration.

## Abstract

The unique physicochemical properties of gold nanoparticles (GNPs) have made them versatile tools for biomedical applications, such as imaging, therapy, and drug delivery. The surface modification of GNPs with polymers or biomolecules can enhance their colloidal stability and facilitate internalization into cells. However, the efficient and biocompatible delivery to the central nervous system remains a major challenge, as many existing nanocarriers show poor capacity to cross the blood-brain barrier. We developed a method to coat GNPs with linear polyethyleneimine (GNP@PEI) through a chemical reduction bottom-up approach, in which linear PEI hydrochloride acts simultaneously as a reducing and stabilizing agent of colloidal dispersion. This strategy yielded monodisperse spherical GNP@PEI nanoparticles with an average diameter of 50 nm. The physicochemical profile, biocompatibility, and capacity for neural uptake of this potentially brain-targeted nanoplatform were then evaluated. GNP@PEI nanoparticles exhibited high biocompatibility in several primary neural cultures and cell lines, with cellular uptake showing clear cell-type-dependent differences. In vivo studies carried out in a murine model demonstrated that after the intranasal or intraperitoneal administrations of GNP@PEI nanoparticles, detectable levels of gold were found in several organs, including the brain. Collectively, these findings highlight the potential of GNP@PEI as a promising nanoplatform for brain-targeted delivery and for advancing the development of therapeutic strategies for neurological disorders.