RESUMO
Engineering plasmonic nanomaterials or nanostructures towards ultrasensitive biosensing for disease markers or pathogens is of high importance. Here we demonstrate a systematic approach to tailor effective plasmonic nanorod arrays by combining both comprehensive numerical discrete dipole approximations (DDA) simulation and transmission spectroscopy experiments. The results indicate that 200×50 nm nanorod arrays with 300×500 nm period provide the highest figure of merit (FOM) of 2.4 and a sensitivity of 310 nm/RIU. Furthermore, we demonstrate the use of nanorod arrays for the detection of single nucleotide polymorphism in codon 12 of the K-ras gene that are frequently occurring in early stages of colon cancer, with a sensitivity down to 10 nM in the presence of 100-fold higher concentration of the homozygous genotypes. Our work shows significant potential of nanorod arrays towards point-of-care applications in diagnosis and clinical studies.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias do Colo/genética , DNA de Neoplasias/genética , Análise de Sequência com Séries de Oligonucleotídeos/instrumentação , Polimorfismo de Nucleotídeo Único/genética , Ressonância de Plasmônio de Superfície/instrumentação , Técnicas Biossensoriais/instrumentação , Neoplasias do Colo/diagnóstico , Análise Mutacional de DNA/instrumentação , DNA de Neoplasias/análise , Desenho de Equipamento , Análise de Falha de Equipamento , Marcadores Genéticos/genética , Humanos , Nanotubos/química , Nanotubos/ultraestrutura , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Analysis of molecular interaction and conformational dynamics of biomolecules is of paramount importance in understanding their vital functions in complex biological systems, disease detection, and new drug development. Plasmonic biosensors based upon surface plasmon resonance and localized surface plasmon resonance have become the predominant workhorse for detecting accumulated biomass caused by molecular binding events. However, unlike surface-enhanced Raman spectroscopy (SERS), the plasmonic biosensors indeed are not suitable tools to interrogate vibrational signatures of conformational transitions required for biomolecules to interact. Here, we show that highly tunable plasmonic metamaterials can offer two transducing channels for parallel acquisition of optical transmission and sensitive SERS spectra at the biointerface, simultaneously probing the conformational states and binding affinity of biomolecules, e.g., G-quadruplexes, in different environments. We further demonstrate the use of the metamaterials for fingerprinting and detection of the arginine-glycine-glycine domain of nucleolin, a cancer biomarker that specifically binds to a G-quadruplex, with the picomolar sensitivity.
