China Pharmaceutical university
Preparation of RGD Incorporating Silica Nanoparticles and Surfaces to Tune Cell Adhesion
Introduction
Over the past few decades, nano-drug delivery systems have achieved significant advances in the biomedical field, which has enabled more effective drug administration by depressing the toxic side effect, increasing efficacy and duration of drug activity, as well as controllable drug release. Specifically, nanoparticles play a critical role in brain cancer due to access to the blood-brain barrier (BBB), which protecting the brain from flotsam or jetsam in the blood, including many therapeutic agents. The application of silica nanoparticles as a biocompatible carrier has a prominent position in the studies. Basically, silica is widely present in living nature, from single-celled organisms to more evolved plants, with better biocompatibility than other metal oxides such as titanium and iron oxide1. Compared with traditional nanoparticles, silica offers advantages of releasing its cargo in greater tendency and degrading in the presence of a reducing agent. The strong Si-O bond allows the particles to be more stable during external changes like degradation and mechanical force1. Additionally, the abundant presence of silanol groups (Si-OH) at the silica surface makes them markedly hydrophilic with a high affinity to phospholipids2. In other words, silica particles can be actively taken up by cells. Then, the drug entrapped in the nanoparticle matrix is delivered to particular targeted-sites and released.
However, biomaterials are subjected to an active environment when implanted in vivo due to protein coated cell surfaces. Thus, advances in nano-drug delivery require bio-functional materials that can interact with cells in a biological manner. Since the discovery of RGD (Arginine-Glycine-Aspartic acid) peptides has been published to promote cell adhesion in 19843, RGD has been extensively functionalized as a cell-bind sequence to stimulate the adhesion on synthetic surfaces 456. RGD peptides can also be used to address selectively certain cell lines and elicit specific cell responses7. Although many other important cell adhesion motifs have been identified, RGD is unique due to its broad distribution and usage. RGD sites were identified in many ECM proteins and shown to bind half of the over 20 known integrins, which comprise the most numerous family of cell adhesion receptors8. The process of integrin mediated cell adhesion is defined as a cascade of four steps: cell attachment, cell spreading, organization of actin cytoskelection, and formation of focal adhesions9.Moreover, their integrin affinity is different with respect to their flanking amino acids.
In this study, we will show that RGD-peptide surface decoration of silica nanoparticles and glass surfaces effectively enhanced cell adhesion.
