A Facile Method To Encapsulate Proteins in Silica Nanoparticles: Encapsulated Green Fluorescent Protein as a Robust Fluorescence Probe

摘要

The encapsulation of proteins in biocompatible silica nanoparticles (NPs) has been extensively studied for many applications, such as biosensors, bioreactors, imaging, and drug delivery. Unfortunately, a recent study has shown that the encapsulation of a protein in silica NPs is critically dependent on the pI value of the protein. Negatively charged proteins (pI<7) are difficult to encapsulate and escape easily because of repulsion with the negative charges on the silica NPs. Herein, we report a facile method to encapsulate proteins, including negatively charged proteins. We show that His-tagged enhanced green fluorescent protein (EGFP; His tag = polyhistidine; pI = 5.99) can be easily and stably encapsulated in silica NPs by using the widely used reverse-microemulsion method with a small amount of additional calcium ions. The remarkably improved fluorescence properties and stability make this EGFP-encapsulated silica NP a robust and safe fluorescence probe.