New Laser Optoacoustic Spectroscopy (LOS) System to quantify Gold Nanoparticles in a Liquid Tissue Phantom for Biomedical Applications
H. Lamela
Optoelectronic and Laser Technology Group (GOTL), Carlos III de Madrid University, 28911 Leganes, Madrid, Spain
Abstract:
The increasing demand for new techniques to enhance the spectroscopic characterisation and optical contrast of in-vivo unhealthy tissue is at the forefront of new innovations in nanomedicine. Such novel optical based medical techniques can provide physiological definition, enhanced therapeutic efficiency and aid in early and effective diagnostic decisions. Targeted gold nanostructures are forming an integral part in solving current demands for biomedical applications, already providing numerous advances in fields of high sensitive diagnostic imaging (Eghtedari, Oraevsky et al. 2007; Eghtedari, Liopo et al. 2009), optical enhanced targeted drug delivery (Han, You et al. 2006; Yih and Al-Fandi 2006) and localized cancer cell destruction by means of phototherapy (Huang, Jain et al. 2007; Rozanova and Zhang 2009). Knowledge of the optical properties of such nanostructures is vital for efficient medical procedures.
In this paper, a novel real-time Laser Optoacoustic Spectrometer (LOS) prototype which demonstrates the potential of the photon to ultrasound conversion, via optoacoustics, is presented and proven to be a valuable technique for characterisation of gold nanorod solutions within turbid media that mimics the optical properties of healthy soft tissue. This analysis has been motivated by the authors previous work in the field of nanoparticle concentration characterization at a single wavelength (532 nm) (Cunningham and Lamela 2010) and spectroscopic characterisation of spherical nanoparticles within the visible range from 410 to 650 nm (Lamela and Cunningham 2010). In this paper real-time results from the LOS on an embedded gold nanorod colloidal solution are presented for the complete wavelength range from 410 nm to 1000 (see Figure 1 (left)) The optical source used is a Q-switched Nd:YAG pumped Optical Parametric Oscillator (OPO) controlled by specifically designed software. A comparative analysis of results obtained from a parallel reference measurement scheme, based on standard collimated optical transmission (see Figure 1 (right)) and standard UV-VIS spectrophotometry will be provided.
