VPAC receptor mediated tumor cell targeting by protamine based nanoparticles.

The receptors for vasoactive intestinal peptide (VIP), VPAC1-, VPAC2-, and PAC1-receptor are overexpressed by various tumor cells. VIP can target these receptors and transport conjugates into the cell. However, the use of VIP for tumor cell targeting is hampered by the peptides short half-lives due to enzymatic degradation. Because protamine-based nanoparticles (proticles) protect the peptide and serve as peptide depot, we explored the potential of proticles as carrier for VIP-conjugated molecules. The VIP-loaded proticles were stable as shown by Fluorescence Correlation Spectroscopy. With Confocal Laser Scanning Microscopy, we observed VIP-loaded proticles to specifically target the tumor cells. The cell binding triggered the substance release and conjugate internalization of VIP-Cy3 in vitro and ex vivo by human tumors. We observed VIP releasing proticle depots distributed in rat tissue and human tumors. Our findings warrant further studies to explore the proticles potential to enable peptide-mediated targeting for in vivo and clinical applications.

Emerging applications of fluorescence spectroscopy in medical microbiology field.

There are many diagnostic techniques and methods available for diagnosis of medically important microorganisms like bacteria, viruses, fungi and parasites. But, almost all these techniques and methods have some limitations or inconvenience. Most of these techniques are laborious, time consuming and with chances of false positive or false negative results. It warrants the need of a diagnostic technique which can overcome these limitations and problems. At present, there is emerging trend to use Fluorescence spectroscopy as a diagnostic as well as research tool in many fields of medical sciences. Here, we will critically discuss research studies which propose that Fluorescence spectroscopy may be an excellent diagnostic as well as excellent research tool in medical microbiology field with high sensitivity and specificity.

Liposomal vasoactive intestinal peptide for lung application: protection from proteolytic degradation.

Inhalative administration of vasoactive intestinal peptide (VIP) is a promising approach for the treatment of severe lung diseases. However, the clinical use of VIP is limited by the fact that the peptide is prone to rapid degradation mechanisms and proteolytic digestion. Accordingly, VIP exhibits a very short period of activity in the lung. To overcome this problem, we have designed a liposomal drug delivery system for VIP and characterized it in terms of its potential to protect VIP from enzymatic cleavage. The proteolytic conditions of the lung, the target site of aerosolic administered VIP, were mimicked by bronchoalveolar lavage fluid (BALF), a lung surfactant solution, obtained by fiberoptic bronchoscopy. Thus, the stability of VIP was assessed by its resistance to enzymatic degradation in BALF, using a combination of high pressure liquid chromatography with mass spectrometry. We found that free VIP was rapidly digested, whereas liposomal-associated VIP remained intact. By fluorescence spectroscopic techniques using fluorescent-labelled VIP we got strong indications that the tight association of VIP with the lipid membrane is only minimally affected upon incubation with BALF. Loading capacity and stability of EtCy3-VIP loaded liposomes were measured by fluorescence fluctuation spectroscopy. Finally, the protective properties of the liposomes were also expressed in the maintained biological activity of the peptide incubated with BALF.

Detection of nanometer-sized particles in living cells using modern fluorescence fluctuation methods.

Nanosized materials are increasingly used in medicine and biotechnology but originate also from various aerosol sources. A detailed understanding of their interaction with cells is a prerequisite for specific applications and appraisal of hazardous effects. Fluorescence fluctuation methods are applied to follow the time-course of the translocation and distribution of fluorescent 20 nm polystyrene nanoparticles with negative surface charges in HeLa cells under almost physiological conditions. The experimental results demonstrate that singular particles enter the cell without significant contribution by endocytotic mechanisms and are distributed within the cytoplasm. Subsequently aggregation is observed, which can be blocked by cytotoxins, like Genistein and Cytochalasin B, interfering with cellular uptake processes. The observed non-active uptake is due to non-specific interactions with the cell surface and could be responsible for distribution of nanometer-sized materials in tissue.