Kye Robinson1,3, Kristofer Thurecht2,4 and Simon Corrie1,2,3,4*


1Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia
2Centre for Advanced Imaging, Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD 4072, Australia
3ARC Centre for BioNano Science (Monash node), Clayton, Victoria, Australia
4ARC Centre for Bio-Nano Science (QLD node), Brisbane, Queensland, Australia


Continuous monitoring of biomarkers in biological environments is a key challenge for the development of biosensors capable of providing real-time feedback1. Sensors capable of continuous pH monitoring have already found applications in detection of bacterial infections and have potential for aiding in treatment of diseases with a highly dynamic nature1.  Nanoparticle based “optodes” have emerged as sensitive and tuneable biosensors, using chromo/ionophores to generate analyte-specific changes in fluorescence spectra in a dynamic and reversible manner. Current key limitations of these materials include leaching of reagents from the nanoparticles over time, combined with poor colloidal stability in biological fluids. 

Organosilica is a promising material for developing stable biosensors, allowing simple control over size, interfacial chemistry and porosity. This presentation will describe the development of a core-shell nanoparticle containing a mixture of covalently incorporated pH-sensitive (shell) and pH-insensitive (core) fluorescent dyes. The attachment of anti-fouling polymers to reduce aggregation and biofouling in biological media will also be discussed. Fluorescence analysis of the nanoparticles reveals that the shell/core fluorescence ratio is highly sensitive to pH over a physiological range (Figure 1) with the response time dependent on the properties of the particle shell. Changes in shell thickness and porosity can decrease response time at the cost of the dynamic range. Here we will present our latest results focussed on using this particle as a pH sensor, including analysis and modulation of the response time, stability to leaching, and colloidal stability in protein and serum-containing fluids.

Figure 1: pH Calibration and Reversibility: A) pH dependant fluorescence change between pH 3-8 around the pKa (6.4) of fluorescein. B) Reversibility of fluorescence response between pH 5 and 7 over 4 cycles response time was calculated to be 3.5 minutes.

1 Corrie, S. R. et al., Analyst, 2015, 140, 4350-4364

Biographic Details
Name: Kye Robinson
Title: Mr
Affiliation, Country: Monash University, Australia
Phone: +0409720904 E-mail:
Research interests: Invivo sensors, nanoparticle synthesis, antifouling polymers