Biomolecular Sensing and Biomedical Properties of Gold Nanorods

• Main Authors: Cheng-Dah Chen, 陳正達
• Other Authors: Wang C.R. Chris
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/52973668784429286903

博士 === 國立中正大學 === 化學所 === 94 === It is known that the absorption spectra of AuNRs are characterized by the dominant longitudinal surface plasmon band (SPlong, at a longer wavelength) and the much weaker transverse surface plasmon band (SPtrans, at a shorter wavelength, ca. 520 nm), with the position of the SPlong band being strongly dependent on the aspect ratio of the AuNRs. Meanwhile, gold nanorods (AuNRs) possess extremely large photoabsorption cross-sections for the characteristic longitudinal surface plasmon (SPlong) resonant absorption band. For example, the absorption coefficient at 950 nm for AuNRs having a mean aspect ratio of 5 is ca. 5.5*10(9) (M–1•cm–1). The resonant wavelength of the SPlong absorption maximum, which is sensitive to the mean particle aspect ratio, has a very wide wavelength range from Vis. to NIR that can be utilized to tune the SPlong band for the particular needs of the application. There are three major subjects in my thesis which all relate to the SPlong absorption band: (I) A new label-free LSPR sensor, which retains many of the desirable features of SPR sensors: This sensor is easy to fabricate, and requires only a Vis-NIR spectrometer for detection purposes. More importantly, the sensor operates in the NIR region and is potentially useful for detecting low concentration of analytes in whole blood within minutes without any sample preparation. We demonstrate the feasibility of using the lmax of SPlong band in the proposed biomolecular sensing scheme. The sensor containing AuNRs, with a mean aspect ratio of 5.2, exhibits a sensitivity of ca. 366 nm/RIU (refractive index unit), which increases accordingly with the increase of the particle mean aspect ratios. Such a biosensor was further modified to demonstrate its effectiveness in quantitative detection for selective binding events, such as biotin/streptavidin pairs. Results showed that the spectral lmax shifts linearly to the streptavidin concentration. The results from both experiment and model calculations strongly indicate the efficacy of the longitudinal surface plasmon absorption band in biosensing. (II) Laser-induced hyperthermia therapy in the cancer cells selective targeted nanoprobes containing AuNRs: This highly efficient thermotherapy is also wavelength-selective. The large absorption coefficients, strong optothermal effects, and wavelength tunability of AuNR systems also make them ideal candidates for use in biomedical molecular imaging. Anti-HER2 monoclonal-antibody (HER2mAb) was chosen to carry AuNRs for specific recognition of HER2 over-expression cancer cells. The AuNRs efficiently transform near-IR light into heat. The local heating is sufficiently high to successfully damage the neighboring cancer cells within a few minutes of laser irradiation. By the way, the generation of acoustic wave signal from the heat effectively discerned the cancer cell with and without nanoprobes. AuNRs have been demonstrated as being useful in both the imaging and NIR thermal therapy of cancer cells. (III) Particles self-assembly features structural control in thermodynamically disfavored means. We set out this work to aim at developing a simple, yet effective, nanoparticle self-assembly route to link gold nanorods in a way of end-to-end fashion forming another overall 1D nanostructure in order to apply in tissue engineering or self-assemble contact end.