Macroscopic and microscopic fluorescence spectroscopy of colorectal benign and malignant lesions - diagnostically important features.

Fluorescence spectroscopy is a sensitive, fast and non-invasive tool for a diagnostics of cancerous gastrointestinal lesions. It could be applied for in situ detection of tumours during primary endoscopic observations or as add-on measurement modality during microscopic observations of tissue histology slides for their initial or retrospective diagnosis. Therefore, we are looking for diagnostically important features of normal and cancerous tissue areas in a broad spectral range for gastrointestinal tissues ex vivo using two steady-state macroscopic fluorescent spectroscopic modalities and by confocal fluorescent microscopic detection. Results obtained from autofluorescence spectroscopy of benign and malignant lower part gastrointestinal tract (GIT) lesions from freshly excised tissues during surgical removal of the lesions in 18 patients (22 lesions), were compared with the spectral measurements obtained during confocal fluorescent microscopy observations of unstained tissue slides using 405 nm excitation. Excitation-emission matrices (EEMs) were used for ex vivo measurements with applied excitation in 280-440 nm spectral region and emission observed between 300 and 700 nm. Synchronous fluorescence spectroscopy (SFS) approach was also applied to improve the spectral resolution of the observed complex emission spectra. Specific fluorescent features observed, related to presence of structural proteins, co-enzymes and endogenous porphyrins in the tissues investigated, allow discriminating normal mucosa from benign polyps and malignant carcinoma lesions with diagnostic accuracy up to 94.4%.

Light-induced antibacterial activity of electrospun chitosan-based material containing photosensitizer.

Increasing antimicrobial resistance requires the development of novel materials and approaches for treatment of various infections. Utilization of photodynamic therapy represents an advanced alternative to antibiotics and metal-based agents. Here, we report the fabrication of electrospun material that possesses benefits of both topical antimicrobial and photodynamic therapies. This material combines chitosan, as a biocompatible polymer, and a second generation photosensitizer. The incorporation of photosensitizer doesn't affect the material morphology and its nearly uniform distribution in fibers structure was observed by confocal Raman microscopy. Owing to photosensitizer the prepared material exhibits the light-induced and spatially limited antimicrobial activity that was demonstrated against Staphylococcus aureus, an important etiological infectious agent. Such material can be potentially used in antibacterial therapy of chronic wounds, infections of diabetic ulcers, and burns, as well as rapidly spreading and intractable soft-tissue infections caused by resistant bacteria.

Impact of high-frequency ultrasound on nanocomposite microcapsules: in silico and in situ visualization.

The impact of high-frequency (1.2 MHz) ultrasound with a power density of 0.33 W cm(-2) on microcapsule nanocomposite shells with embedded zinc oxide nanoparticles was investigated by exploring modeling simulations and direct visualization. For the first time the sonication effect has been monitored in situ on individual microcapsules upon exposure of their aqueous suspension to ultrasound. The stress distribution on the microcapsule shell for the impact of ultrasound with high (1.2 MHz) and low (20 kHz) frequency at two fixed intensities (0.33 and 30 W cm(-2)) has been modeled. As shown in silico and experimentally the nanocomposite microcapsules were destroyed more effectively by the action of high-frequency (1.2 MHz) ultrasound in comparison to the low frequency (20 kHz) one with the same power density.