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The necessity for decentralization of diagnostic technology, from a biomedical laboratory to near the patient sites, has driven the research community to engage the new generation smartphones with novel diagnostic and detection platforms. In this work, we will use state-of-the-art knowledge and state-of-the-art technology to construct an innovative platform on mobile devices with a future outlook of in vivo intervention. Specifically, we have built a low-cost smartphone-based microscopy technique by applying optics principles. With this technique we revealed the ability to identify PMMA beads circulating in a microfluidic channel, comparing its performance with the results obtained with an optical trapping device. The proposed platform could act as a detection and image analysis station for rapid and sensitive imaging of human cell collections from body fluids (biomedical diagnosis) or for screening of the water quality in remote areas (environmental pollution monitoring).

The introduction of new upconverting nanoparticles (UPCNPs) in the tumor area is being investigated worldwide as a solution for deep tissue theranostics interventions. Moreover, as the development of biophotonics techniques permits bioimaging in nanoscale, both photodynamic and photothermal sensing should be achieved even at cellular level with minimum perturbation, i.e., in absence of any physical contact between cells and sensing units at a single-cell level via optical tweezers. In our work, we discuss the biophotonic upconversion mechanism of nanoparticles’ excitation/emission at cellular level, under laser trapping conditions, via considering laser radiation of NIR (specifically at λ = 808 nm) for optimal penetration in biological tissues. Moreover, a theoretical simulation model will be presented for evaluation of the electric field distribution in optically trapped particles. Water soluble UPCNPs with maximum absorbance wavelength at λ = 808 nm and emission at 545 nm and 660 nm will be studied. The photoluminescence of biocompatible UPCNPs could provide a promising powerful tool for PDT single-cell analysis and/or for photothermal enhancement and sensing in an optical tweezers’ platform.

Photodynamic therapy (PDT) is a non-invasive procedure mainly used for treatment of malignancies. It is based on cytotoxic products generation after the excitation of absorbed photosensitizing drugs by non-ionizing radiation. The wavelength chosen is usually in the 620 - 700 nm region, resulting in limited tissue penetration depth. The relatively low irradiance values and the treatment time that, in most cases, lasts for a few minutes result in limited photothermal effects, which are usually overlooked. Therefore, in this study we computationally assess the temperature distribution during PDT in a cancer bearing mouse model. A user-friendly application is created that could be used in the treatment planning step of PDT. It receives as input various parameters, such as laser power, beam radius, irradiation time, body temperature and returns the maximum tissue temperature and irradiance values. Furthermore, it offers visualization of the generated effects through the spatial distribution of temperature, irradiance, acute necrosis and damaged tissue percentage that are presented in the form of interactive 3D plots. The conducted simulations reveal that 43 °C, which are in the hyperthermia range, are difficult to be excessed in PDT clinical practice, although topical thermal effects are observed.

Resumen del trabajo presentado en el International Multidisciplinary Microscopy Congress (INTERM2013), celebrado en Antalya (Turquía), del 10 al 13 de octubre de 2013, Micromanipulation of dielectric objects, from polystyrene spheres to living cells, is achieved when radiation pressure forces create stable trapping by highly focused laser beams through microscopes. However, the impressive history of optical trapping is shadowed by the light diffraction limit, as research currently has focused on materials below the micron scale, requiring stronger optical confinement and higher intensities than can be provided by the conventional optical tweezers. Recently, plasmonic nanostructures have entered the field, either to assist or enhance it. In this study, we present experimental results on using localized fields of metallic structures for efficient trapping, with various patterns (dots, fringes and squares). The patterns were produced by laser interferometry on almost continuous Ag or Au films on glass and glass covered by an amorphous Al2O3 layer (10 nm thick) respectively. We have calculated the optical forces by measuring the particle’s escape velocity. The results show that the effective quality factor Q in the patterned metal film is enhanced by a factor >10, with respect to the unpatterned metal film and a factor >100, with respect to an uncoated glass. In addition, mathematical simulation of plasmonic fields is investigated to confirm and explain theoretically, the experimentally observed plasmonic enhancement., RP acknowledges a grant from the JAE-doc program co-funded by European Social Fund. This work has partially been supported by MAT2011-28345-C02-02 (Spain) projects.