Recent progress in the engineering of multifunctional colloidal nanoparticles for enhanced photodynamic therapy and bioimaging.

This up-to-date review summarizes the design and current fabrication strategies that have been employed in the area of mono- and multifunctional colloidal nanoparticles - nanocarriers well suited for photodynamic therapy (PDT) and diagnostic purposes. Rationally engineered photosensitizer (PS)-loaded nanoparticles may be achieved via either noncovalent (i.e., self-aggregation, interfacial deposition, interfacial polymerization, or core-shell entrapment along with physical adsorption) or covalent (chemical immobilization or conjugation) processes. These PS loading approaches should provide chemical and physical stability to PS payloads. Their hydrophilic surfaces, capable of appreciable surface interactions with biological systems, can be further modified using functional groups (stealth effect) to achieve prolonged circulation in the body after administration and/or grafted by targeting agents (such as ligands, which bind to specific receptors uniquely expressed on the cell surface) or stimuli (e.g., pH, temperature, and light)-responsive moieties to improve their action and targeting efficiency. These attempts may in principle permit efficacious PDT, combination therapies, molecular diagnosis, and - in the case of nanotheranostics - simultaneous monitoring and treatment. Nanophotosensitizers (nano-PSs) should possess appropriate morphologies, sizes, unimodal distributions and surface processes to be successfully delivered to the place of action after systemic administration and should be accumulated in certain tumors by passive and/or active targeting. Additionally, physically facilitating drug delivery systems emerge as a promising approach to enhancing drug delivery, especially for the non-invasive treatment of deep-seated malignant tissues. Recent advances in nano-PSs are scrutinized, with an emphasis on design principles, via the promising use of colloid chemistry and nanotechnology.

Biological characterization of the modified poly(dimethylsiloxane) surfaces based on cell attachment and toxicity assays.

Poly(dimethylsiloxane) (PDMS) is a material applicable for tissue and biomedical engineering, especially based on microfluidic devices. PDMS is a material used in studies aimed at understanding cell behavior and analyzing the cell adhesion mechanism. In this work, biological characterization of the modified PDMS surfaces based on cell attachment and toxicity assays was performed. We studied Balb 3T3/c, HMEC-1, and HT-29 cell adhesion on poly(dimethylsiloxane) surfaces modified by different proteins, with and without pre-activation with plasma oxygen and UV irradiation. Additionally, we studied how changing of a base and a curing agent ratios influence cell proliferation. We observed that cell type has a high impact on cell adhesion, proliferation, as well as viability after drug exposure. It was tested that the carcinoma cells do not require a highly specific microenvironment for their proliferation. Cytotoxicity assays with celecoxib and oxaliplatin on the modified PDMS surfaces showed that normal cells, cultured on the modified PDMS, are more sensitive to drugs than cancer cells. Cell adhesion was also tested in the microfluidic systems made of the modified PDMS layers. Thanks to that, we studied how the surface area to volume ratio influences cell behavior. The results presented in this manuscript could be helpful for creation of proper culture conditions during in vitro tests as well as to understand cell response in different states of disease depending on drug exposure.

Lab-on-a-chip systems for photodynamic therapy investigations.

In recent years photodynamic therapy (PDT) has received widespread attention in cancer treatment due to its smaller surgical trauma, better selectivity towards tumor cells, reduced side effects and possibility of repeatable treatment. Since cancer is the second cause of death worldwide, scientists constantly seek for new potential therapeutic agents including nanotechnology-based photosensitizers used in PDT. The new-designed nanostructures must be carefully studied and well characterized what require analytically useful and powerful tools that enable real progress in nanoscience development. This review describes the current status of PDT investigations using microfluidic Lab-on-a-Chip systems, including recent developments of nanoparticle-based PDT agents, their combinations with different drugs, designs and examples of in vitro applications. This review mainly lays emphasis on biological evaluation of FDA approved photosensitizing agents as well as newly designed nanophotosensitizers. It also highlights the analytical performances of various microfluidic Lab-on-a-chip systems for PDT efficacy analysis on 3D culture and discusses microsystems designs in detail.

Evaluation of nanoencapsulated verteporfin's cytotoxicity using a microfluidic system.

A new-generation of nanoencapsulated photosensitizers could be a good solution to perform effective photodynamic therapy (PDT). In this paper, we present physicochemical characterization and cellular investigation of newly prepared long-sustained release oil-core polyelectrolyte nanocarriers loaded with verteporfin (nano VP) in relation to free VP. For this purpose, a macroscale multiwell plates and multifunctional microfluidic system (for three types of cell cultures: monoculture, coculture and mixed culture) were used. A physical analysis of nano VP showed its high stability, monodispersity with unimodal shape and highly positive charge, what made them good candidates for cancer treatment. Biological properties (cellular internalization and uptake as well as cytotoxicity) of nano and free VP were evaluated using both carcinoma (A549) and normal (MRC-5) human lung cells. It was investigated that verteporfin was accumulated in cancer cells preferentially. Low cytotoxicity of the tested photosensitizer was observed in both macro, and microscale. However, in experiments performed in the microsystem, nano VP allowed the reduction of cytotoxic effect, especially in relation to the normal cells. It could result from the specific environment of cell growth in the microsystem which can quite closely mimic the in vivo conditions. Our results suggest that the presented microsystem could be a very useful microtool for testing of new generation of photosensitizers in various configurations of cell cultures, which are difficult to perform in the macroscale. Moreover, the prepared nano VP could be successfully used for further research i.e. evaluation of PDT procedures.

Microfluidic platform for photodynamic therapy cytotoxicity analysis of nanoencapsulated indocyanine-type photosensitizers.

The application of nanotechnology is important to improve research and development of alternative anticancer therapies. In order to accelerate research related to cancer diagnosis and to improve the effectiveness of cancer treatment, various nanomaterials are being tested. The main objective of this work was basic research focused on examination of the mechanism and effectiveness of the introduction of nanoencapsulated photosensitizers to human carcinoma (A549) and normal cells (MRC-5). Newly encapsulated hydrophobic indocyanine-type photosensitizer (i.e., IR-780) was subjected to in vitro studies to determine its release characteristics on a molecular level. The photosensitizers were delivered to carcinoma and normal cells cultured under model conditions using multiwell plates and with the use of the specially designed hybrid (poly(dimethylsiloxane) (PDMS)/glass) microfluidic system. The specific geometry of our microsystem allows for the examination of intercellular interactions between cells cultured in the microchambers connected with microchannels of precisely defined length. Our microsystem allows investigating various therapeutic procedures (e.g., photodynamic therapy) on monoculture, coculture, and mixed culture, simultaneously, which is very difficult to perform using standard multiwell plates. In addition, we tested the cellular internalization of nanoparticles (differing in size, surface properties) in carcinoma and normal lung cells. We proved that cellular uptake of nanocapsules loaded with cyanine IR-780 in carcinoma cells was more significant than in normal cells. We demonstrated non cytotoxic effect of newly synthesized nanocapsules built with polyelectrolytes (PEs) of opposite surface charges: polyanion-polysodium-4-styrenesulphonate and polycation-poly(diallyldimethyl-ammonium) chloride loaded with cyanine IR-780 on human lung carcinoma and normal cell lines. However, the differences observed in the photocytotoxic effect between two types of tested nanocapsules can result from the type of last PE layer and their different surface charge.