Near-Infrared Surface-Enhanced-Raman-Scattering-Mediated Detection of Single Optically Trapped Bacterial Spores

A novel methodology has been developed for the investigation of bacterial spores. Specifically, this method has been used to probe the spore coat composition of two different Bacillus stearothermophilus variants. This technique may be useful in many applications; most notably, development of novel detection schemes toward potentially harmful bacteria. This method would also be useful as an ancillary environmental monitoring system where sterility is of importance (i.e., food preparation areas as well as invasive and minimally invasive medical applications). This unique detection scheme is based on the near-infrared (NIR) surface-enhanced Raman scattering (SERS) from single, optically trapped, bacterial spores. The SERS spectra of bacterial spores in aqueous media have been measured using SERS substrates based on ∼60-nm-diameter gold colloids bound to 3-aminopropyltriethoxysilane derivatized glass. The light from a 787-nm laser diode was used to trap and manipulate as well as simultaneously excite the SERS of an individual bacterial spore. The collected SERS spectra were examined for uniqueness and the applicability of this technique for the strain discrimination of Bacillus stearothermophilus spores. Comparison of normal Raman and SERS spectra reveals not only an enhancement of the normal Raman spectral features but also the appearance of spectral features absent in the normal Raman spectrum.

[1]  S. Chu,et al.  Observation of a single-beam gradient force optical trap for dielectric particles. , 1986, Optics letters.

[2]  Laurie L. Wood,et al.  New biochip technology for label-free detection of pathogens and their toxins. , 2003, Journal of microbiological methods.

[3]  M. Houlne,et al.  Confocal Raman microscopy for monitoring chemical reactions on single optically trapped, solid-phase support particles. , 2002, Analytical chemistry.

[4]  J. Zuo,et al.  Enhancement mechanism of SERS from cyanine dyes adsorbed on Ag2O colloids , 1997 .

[5]  S. Yamashita,et al.  Laser Raman Spectroscopy of Lyophilized Bacterial Spores , 1986, Microbiology and immunology.

[6]  J. M. Harris,et al.  Characterization of silane-modified immobilized gold colloids as a substrate for surface-enhanced Raman spectroscopy. , 2001, Analytical chemistry.

[7]  A. Resnick.  Design and construction of a space-borne optical tweezer apparatus , 2001 .

[8]  J. Popp,et al.  Raman spectroscopic investigation of polycyanacrylate capsules , 1999 .

[9]  K. Schütze,et al.  Force generation of organelle transport measured in vivo by an infrared laser trap , 1990, Nature.

[10]  Yong-qing Li,et al.  Near-infrared Raman spectroscopy of single optically trapped biological cells. , 2002, Optics letters.

[11]  B. Schrader,et al.  Uncertainties in temperature measurements of optically levitated single aerosol particles by Raman spectroscopy , 1999 .

[12]  Xin Houwen,et al.  Enhancement origin of SERS from pyridine adsorbed on AgCl colloids , 1987 .

[13]  W. Nelson,et al.  UV resonance Raman spectra of bacteria, bacterial spores, protoplasts and calcium dipicolinate , 1990 .

[14]  Morita,et al.  Investigation of the molecular extraction process in single subpicoliter droplets using a near-infrared laser Raman trapping system , 2000, Analytical chemistry.

[15]  A. Ashkin,et al.  Optical trapping and manipulation of single cells using infrared laser beams , 1987, Nature.

[16]  A. Ashkin.  Acceleration and trapping of particles by radiation pressure , 1970 .

[17]  K. Torimitsu,et al.  Single Nanoparticle Trapping Using a Raman Tweezers Microscope , 2002 .

[18]  J. Käs,et al.  The optical stretcher: a novel laser tool to micromanipulate cells. , 2001, Biophysical journal.

[19]  R. G. Freeman,et al.  Preparation and Characterization of Au Colloid Monolayers , 1995 .

[20]  Ramasamy Manoharan,et al.  UV Resonance Raman Spectra of Bacillus Spores , 1992 .

[21]  A. Ashkin,et al.  Optical trapping and manipulation of viruses and bacteria. , 1987, Science.

[22]  M. S. Zubairy,et al.  FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[23]  T. Spiro,et al.  Raman spectroscopy in vivo: evidence on the structure of dipicolinate in intact spores of Bacillus megaterium. , 1974, Biochemical and biophysical research communications.

[24]  E. Leifson.  Bacterial Spores , 1931, Journal of bacteriology.

[25]  J. Popp,et al.  Raman investigations on laser-trapped gas bubbles , 1997 .