Barcoded Microparticles for Multiplexed Detection

The detection of multiple targets in a single sample is important for many applications, including medical diagnostics, genotyping, and drug discovery. The current approaches to multiplexing, such as planar arrays (such as DNA microarrays) and suspension (particle-based) arrays, require expensive or cumbersome means of encoding, decoding, or functionalizing substrates. Currently, commercially available approaches for multiplexed analysis are cost-prohibitive for high sample throughput, low-cost applications such as bedside diagnostics.

We have developed a method, based on multifunctional barcoded particles, for the sensitive and accurate multiplexed detection of biomolecules. The method is unique in that (1) we can fabricate, encode, and functionalize particles in a single step, (2) the particles are composed of poly(ethylene glycol) hydrogel to increase both sensitivity and specificity, and (3) only a single fluorescent wavelength is required to decode the particles and quantify the corresponding targets. Using an efficient one-step method based on continuous-flow lithography, we synthesize microparticles with multiple functional regions. Each particle bears a fluorescent dot-pattern barcode (capable of providing over a million unique codes) to identify the target(s) it is looking for and one or more spatially separated regions containing a probe where those targets can bind and be detected via fluorescence. In this way, particles from a library can be mixed and incubated in a single sample to simultaneously detect many targets, such as DNA oligomers. The detection of targets is not only sensitive but also extremely specific due to the porous and bio-inert nature of the hydrogel structure that allows target molecules to diffuse and bind deep into the transparent particle surfaces.