Coimbra Laser Lab

Photonics and Reactivity

Photodynamic therapy of cancer

Starting in 1996 new photosensitizers were developed for the photodynamic therapy of cancer. This work lead to two patents of the University of Coimbra, which have been licensed to a start-up pharmaceutical company: Luzitin SA. The company is now leading the project and clinical trials are scheduled to start in 2013. The scientific grounds for the development of such photosensitizers, their properties and their achievements are regularly published in the scientific literature.

Transdermal drug delivery with photoacoustic waves

Building on the expertise of the laboratory since 1990, applications of photoacoustic waves to various processes lead to the finding of their effects on biological membranes. Subject to photoacoustic waves generated by carefully designed piezophotonic materials, the permeability of the skin or of cell membranes was found to increase temporarily without compromising skin recovery of cell viability. The technology was patented by the University of Coimbra and licensed to a start-up technological company: LaserLeap Technologies. The company is pursuing applications of the technology to transdermal drug delivery, instrumental cosmetics and gene therapy.

Optical biopsy dyes

The new frontiers of cancer detection and treatment demand the ability to visualize microstructures that target the diseased tissue. By imaging where, when, and in what extent a marker chromophore appears, it becomes possible to refine basic preclinical research and improve cancer therapy. Optical imaging techniques have the advantage of high sensitivity, high time resolution, strong contrast and good spatial resolution. The optimization of cancer detection using optical imaging requires new contrast agents with strong absorption in the therapeutic window (700 to 850 nm) where tissues are more transparent. This project focuses on the development of contrast agents for fluorescence imaging and for photoacoustic tomography.

Solar energy conversion

Approximately 4.3 × 1020 J of photon energy hit the surface of our planet each hour, which is enough to cover our yearly energy needs. Photochemical conversion of solar photons is one of the most promising and sought after solutions to the current global energy problem. Dye-sensitized solar cells (DSSC) and organic bulk heterojunction solar cells (BHJ) are two examples of systems that allow the conversion of visible sunlight into electricity by inorganic or organic semiconductor materials, which are inexpensive and easy to process on a large scale. The lab is actively involved in the development and characterization of solar cells using strongly near-IR absorbing dyes, new techniques to measure their efficiency, and new forms of photo-piezo-pyroelectric conversion.

Intersecting/Interacting-State Model

The driving force of the work in the lab is the ability to understand and predict how molecular structure influences chemical reactivity and the properties of molecules in general. Rather than relying on time-consuming calculations, the lab specialized in semi-empirical models capable of providing reliable estimates of rate constants for fundamental chemical reactions in a wide variety of media. The Intersecting/Interacting-State Model has been extensively applied to atom transfer, proton transfer, electron and energy transfer, proton-coupled electron transfer and SN2 reactions. It provides the fundamental guidance to the more applied projects carried out in the lab.

Peptide and protein folding

One of the major challenges in the field of Biophysical Chemistry is the study of protein folding mechanisms, i.e., how an unstructured polypeptide chain can rapidly adopt a unique, densely packed, three dimensional structure. Erroneous folding is the molecular basis for a wide range of human disorders, including Alzheimer's and Parkinson's disease. Our aim is to make the early stages of folding experimentally accessible. We use ultrafast pH-jump technique to induce peptide and protein unfolding. The conformational changes during unfolding are monitored by time-resolved photoacoustics calorimetry, enabling the determination of kinetic constants, enthalpy and volume changes accompanying the unfolding process. We focus our study on model peptides with well defined secondary structure and small proteins.