A simple synthetic method has been described to prepare anisotropic gold nanoparticles （AuNPs） possessing unique optical and structural properties at room temperature, and subsequently the nanoparticles have been st...A simple synthetic method has been described to prepare anisotropic gold nanoparticles （AuNPs） possessing unique optical and structural properties at room temperature, and subsequently the nanoparticles have been stabilized by temperature-sensitive poly（N-isopropylacrylamide）, or poly（NIPAM）. Although poly（NIPAM） does not exhibit a strong binding affinity to gold, simply introducing poly（NIPAM） to these unstable anisotropic AuNPs can maintain the original structures and absorption properties for several weeks. This increased stability is presumably caused by the adsorbed polymer layer around the anisotropic AuNPs. The existence of adsorbed linear poly（NIPAM） around the AuNPs is confirmed through the reversible absorption properties of the nanoparticles upon heating and cooling. To verify the presence of weak attractive forces （e.g., van der Waals, dipole-dipole, and possible hydrogen bonding） between the polymer and the AuNPs, various concentrations of linear poly（NIPAM） are introduced during the formation of the AuNPs resulting in the systematical control of the size and roughness of the nanoparticles. In addition, the preferential attachment of pre-formed anisotropic AuNPs on cross-linked poly（NIPAM） nanoparticles indicates the presence of weak attractive forces between AuNPs and poly（NIPAM）. As such, poly（NIPAM） and its derivatives can serve as a useful stabilizing and capping agent to preserve the properties of the anisotropic AuNPs.展开更多
Bacterial sensing is important for understanding the numerous roles bacteria play in nature and in technology,understanding and managing bacterial populations,detecting pathogenic bacterial infections,and preventing t...Bacterial sensing is important for understanding the numerous roles bacteria play in nature and in technology,understanding and managing bacterial populations,detecting pathogenic bacterial infections,and preventing the outbreak of illness.Current analytical challenges in bacterial sensing center on the dilemma of rapidly acquiring quantitative information about bacteria with high detection efficiency,sensitivity,and specificity,while operating within a reasonable budget and optimizing the use of ancillary tools,such as multivariate statistics.This review starts from a general description of bacterial sensing methods and challenges,and then focuses on bacterial characterization using optical methods including Raman spectroscopy and imaging,infrared spectroscopy,fluorescence spectroscopy and imaging,and plasmonics,including both extended and localized surface plasmon resonance spectroscopy.The advantages and drawbacks of each method in relation to the others are discussed,as are their applications.A particularly promising direction in bacterial sensing lies in combining multiple approaches to achieve multiplex analysis,and examples where this has been achieved are highlighted.展开更多
基金supported by Korea Ministry of Environment as The Eco-Innovation Project (Global Top project,No.GT-SWS-11-01-0040-0)
文摘A simple synthetic method has been described to prepare anisotropic gold nanoparticles （AuNPs） possessing unique optical and structural properties at room temperature, and subsequently the nanoparticles have been stabilized by temperature-sensitive poly（N-isopropylacrylamide）, or poly（NIPAM）. Although poly（NIPAM） does not exhibit a strong binding affinity to gold, simply introducing poly（NIPAM） to these unstable anisotropic AuNPs can maintain the original structures and absorption properties for several weeks. This increased stability is presumably caused by the adsorbed polymer layer around the anisotropic AuNPs. The existence of adsorbed linear poly（NIPAM） around the AuNPs is confirmed through the reversible absorption properties of the nanoparticles upon heating and cooling. To verify the presence of weak attractive forces （e.g., van der Waals, dipole-dipole, and possible hydrogen bonding） between the polymer and the AuNPs, various concentrations of linear poly（NIPAM） are introduced during the formation of the AuNPs resulting in the systematical control of the size and roughness of the nanoparticles. In addition, the preferential attachment of pre-formed anisotropic AuNPs on cross-linked poly（NIPAM） nanoparticles indicates the presence of weak attractive forces between AuNPs and poly（NIPAM）. As such, poly（NIPAM） and its derivatives can serve as a useful stabilizing and capping agent to preserve the properties of the anisotropic AuNPs.
基金the National Institute of Allergies and Infectious Diseases under Grant 1RO1AI113219-01.
文摘Bacterial sensing is important for understanding the numerous roles bacteria play in nature and in technology,understanding and managing bacterial populations,detecting pathogenic bacterial infections,and preventing the outbreak of illness.Current analytical challenges in bacterial sensing center on the dilemma of rapidly acquiring quantitative information about bacteria with high detection efficiency,sensitivity,and specificity,while operating within a reasonable budget and optimizing the use of ancillary tools,such as multivariate statistics.This review starts from a general description of bacterial sensing methods and challenges,and then focuses on bacterial characterization using optical methods including Raman spectroscopy and imaging,infrared spectroscopy,fluorescence spectroscopy and imaging,and plasmonics,including both extended and localized surface plasmon resonance spectroscopy.The advantages and drawbacks of each method in relation to the others are discussed,as are their applications.A particularly promising direction in bacterial sensing lies in combining multiple approaches to achieve multiplex analysis,and examples where this has been achieved are highlighted.
