development of colorimetric platforms for biosensing using programmable assembly of aunp-core spherical nucleic acids

Dna molecules have a polymer language with four alphabets that can be designed with an arbitrary sequence, programmed base by base.[1] rather than directing biological processes, synthetic forms of dna are now utilized to program the assembly of nanoparticles. spherical nucleic acids (snas) are an emerging class of three-dimensional nanostructures typically made by arranging linear nucleic acids at high density around a nanoparticle core. [2, 3] programmable assembly of snas is a target-responsive and sequence-specific molecular recognition event. in cases where snas are composed of gold nanoparticles (called aunp-core snas), the programmable assembly events lead to generating naked-eye-observable colorimetric responses. the last two decades have seen a growing trend toward developing aunp-core snas as medical diagnostic probes. this study provides greater insight into the utilization of dna-programmable assembly of gold nanoparticles as a colorimetric transduction event for molecular diagnosis. recently, we developed several strategies based on the target-responsive assembly of aunp-core snas for the “naked-eye” colorimetric detection of severe acute respiratory syndrome coronavirus 2 (sars-cov-2) rna. [4-6] conventional polymerase chain reaction (pcr), which requires minimal laboratory equipment (a simple thermal cycler), was modified for molecular diagnosis via the 5′-exonuclease activity of the dna polymerase. due to public health interest in the management of infectious diseases using simple, accessible, and affordable laboratory equipment, the dna-based programmable assembly strategies have a valuable potential to design biosensors for point-of-care testing.