As one of the major health problems for mankind is cancer, any development for the early detection and effective treatment of cancer is crucial to saving lives. Worldwide, the dream for the anti-cancer procedure of attack is the development of a safe and efficient early diagnosis technique, the so called “optical biopsy”. As early diagnosis of cancer is associated with improved prognosis, several laser based optical diagnostic methods were developed to enable earlier, non-invasive detection of human cancer, as Laser Induced Fluorescence spectroscopy (LIFs), Diffuse Reflectance spectroscopy (DRs), confocal microscopy, and Optical Coherence Tomography (OCT). Among them, Optical Coherence Tomography (OCT) imaging is considered to be a useful tool to differentiate healthy from malignant (e.g. basal cell carcinoma, squamous cell carcinoma) skin tissue. If the demand is to perform imaging in sub-tissular or even sub-cellular level, optical tweezers and atomic force microscopy have enabled the visualization of molecular events underlying cellular processes in live cells, as well as the manipulation and characterization of microscale or even nanoscale biostructures. In this work, we will present the latest advances in the field of laser imaging and manipulation techniques, discussing some representative experimental data focusing on the 21th century biophotonics roadmap of novel diagnostic and therapeutical approaches. As an example of a recently discussed health and environmental problem, we studied both experimentally and theoretically the optical trapping forces exerted on yeast cells and modified with estrogen-like acting compounds yeast cells, suspended in various buffer media.
The field of optical trapping has dramatically grown due to implementation in various arenas including physics, biology,
medicine and nanotechnology. Certainly, optical tweezers are an invaluable tool to manipulate a variation of particles,
such as small dielectric spheres, cells, bacteria, chromosomes and even genes, by highly focused laser beams through
microscope. As the main disadvantage of the conventional optical trapping systems is the diffraction limit of the incident
light, plasmon assisted nanotrapping is reported as a suitable technique for trapping sub-wavelength metallic or dielectric
particles. In this work, firstly, we report briefly on the basic theory of plasmon excitation, focusing on the interaction of
nanoscale metallic structures with laser light. Secondly, experimental and numerical simulation results are also
presented, demonstrating enhancement of the trapping efficiency of glass or SiO2 substrates, coated with Au and Ag
nanostructures, with or without nanoparticles. The optical forces were calculated by measuring the particle’s escape
velocity calibration method. Finally, representative applications of plasmon assisted optical trapping are reviewed, from
cancer therapeutics to fundamental biology and cell nanosurgery.