Nanostructured silver materials for noninvasive medical diagnostics by surface-enhanced Raman spectroscopy

Vapor phase SERS sensor based on mesoporous silica decorated with silver nanoparticles

“…At the same time, ordinary materials for SERS with ecological, pharmaceutical, biological and medical applications are commonly designed for the analysis of liquid analytes [1][2][3][4][5][6][7][8][9][10] while a limited number of actual research efforts has focused on vapor phase detection [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. The latter challenge evidently widens the promising application area of SERS and therefore requires novel approaches for the design of SERS-active materials.…”

Revisiting preparation routes of SERS materials

“…The Surface-enhanced Raman spectroscopy (SERS) method has become one of the most powerful and universal tool for modern analytics in pharmacology, ecology and potentially noninvasive biomedical diagnostics for screening and personal medicine [1][2][3][4][5]. Silver nanoparticles and nanostructured materials are a common choice for SERS measurements due to their broad plasmon resonance, high stability, facile fabrication methods and the largest enhancement for special molecules [3][4][5].…”

“…Silver nanoparticles and nanostructured materials are a common choice for SERS measurements due to their broad plasmon resonance, high stability, facile fabrication methods and the largest enhancement for special molecules [3][4][5]. A complex morphology such as nanoflowers, nanorices, cubes, multipods and nanodendrites, mesocages is achieved by kinetically controlled, aggregation-based, heterogeneously seeded, template-directed growth, selective etching and colloidal system aging; the polyol technique allows one to synthesize silver nanoparticles of a wide variety of shapes and sizes [6][7][8][9][10][11][12][13][14][15][16].…”

“…A complex morphology such as nanoflowers, nanorices, cubes, multipods and nanodendrites, mesocages is achieved by kinetically controlled, aggregation-based, heterogeneously seeded, template-directed growth, selective etching and colloidal system aging; the polyol technique allows one to synthesize silver nanoparticles of a wide variety of shapes and sizes [6][7][8][9][10][11][12][13][14][15][16]. Despite of all possible advantages, the nanoparticles themselves are likely to aggregate uncontrollably in solutions, making it difficult to reproduce SERS results [5,6,11,14]; nanoparticle sols exhibit limited plasmonic tunability as compared to a new class of nanomaterials -colloidosomes composed of a dielectric core and a concentric metal shells with hybridization of plasmon modes supported by an inner cavity and an outer surface of the nanoshell [5,7,9,10]. However, SERS still suffers a lack of reproducibility due to the masking of SERS signals by surfactants or by-products, gradients of electric fields near the nanoparticles and variations of molecule positions with respect to the nanoparticles; commonly used linkers, surfactants, reducing agents and their oxidized forms, halide ions can change the characteristic properties of nanoparticles because of their aging, recrystallization or random formation of aggregates [5,[11][12][13][14].…”

“…Despite of all possible advantages, the nanoparticles themselves are likely to aggregate uncontrollably in solutions, making it difficult to reproduce SERS results [5,6,11,14]; nanoparticle sols exhibit limited plasmonic tunability as compared to a new class of nanomaterials -colloidosomes composed of a dielectric core and a concentric metal shells with hybridization of plasmon modes supported by an inner cavity and an outer surface of the nanoshell [5,7,9,10]. However, SERS still suffers a lack of reproducibility due to the masking of SERS signals by surfactants or by-products, gradients of electric fields near the nanoparticles and variations of molecule positions with respect to the nanoparticles; commonly used linkers, surfactants, reducing agents and their oxidized forms, halide ions can change the characteristic properties of nanoparticles because of their aging, recrystallization or random formation of aggregates [5,[11][12][13][14]. Nanostructured substrates promise much better reproducibility and less toxicity promoting their SERS applications in biology and medicine, especially in highly sensitive lab-on-a-chip devices [5,11,[13][14][15].…”