Development of 6-Thioguanine conjugated PLGA nanoparticles through thioester bond formation: Benefits of electrospray mediated drug encapsulation and sustained release in cancer therapeutic applications.

Polymeric nanoparticle-based successful delivery of hydrophobic drugs is highly desirable for its controlled and sustained release at the disease site, which is a challenge with the current synthesis methods. In the present study, an electrospray mediated facile one-step synthesis approach is explored in which a solution mixture of a hydrophobic drug, 6-thioguanine (Tg) and a biocompatible FDA approved polymer, Poly (d, l-lactide-co-glycolide) (PLGA) is injected in an applied electric field of suitable intensity to prepare drug encapsulated PLGA nanoparticles, PLGA-Tg with high yield. In order to explore the effect of external electric field on Tg loading and delivery applications, the nanoparticles are characterized using EDX, AFM, FESEM, TEM, FTIR, Raman, fluorescence, and mass spectroscopy techniques. The characterization studies indicate that the electric field mediated synthesis exhibits spherical nanoparticles with a homogenous core size distribution of ~60 nm, high encapsulation (~97.22%) and stable conjugation of Tg (via thioester linkages) with PLGA molecules in the presence of the applied electric field. The kinetic study demonstrates the 'anomalous diffusion' (non-Fickian diffusion) release mechanism in which Tg escapes from PLGA matrix with a slow, but steady diffusion rate and the sustained drug release profile continues for 60 days. To check the biological activity of the encapsulated Tg, in-vitro cell studies of the PLGA-Tg are performed on HeLa cells. The MTT assay shows significant cell death after 48 h of treatment, and the cellular internalization of the drug-loaded nanoparticles occurs through pinocytosis mediated uptake, which is established by the AFM analysis. The Raman and mass spectroscopy studies suggest that the PLGA-Tg nanoparticles are rapidly hydrolyzed inside cell cytoplasm to release Tg which initiates apoptosis-mediated cell death confirmed by as DNA fragmentation and membrane blebbing studies. The results clearly emphasize the benefits of electrospray based synthesis of polymeric nanodrug formulation through the formation of chemical bonds between polymer and drug molecules that could be easily implemented in the design and development of an effective nanotherapeutic platform with no typical 'burst effect,' prolonged release profile, and significant toxicity to the cancer cells.

Gold nanoparticle-assisted enhancement in the anti-cancer properties of theaflavin against human ovarian cancer cells.

Redox-active quinones have been reported to show good potential for biological activities, while efforts are directed to explore the usefulness of these materials further in cancer management. Our previous study demonstrated that theaflavin and theaflavin-gallates (tea-extracted polyphenols) selectively induce apoptosis of tumour cells in vitro, but its concentration for showing half-maximal therapeutic response remains a matter of concern. In this report, we demonstrated that if theaflavin is conjugated with gold nanoparticles (AuNPs) to form a nanoconjugate AuNP@TfQ, its apoptotic ability increases significantly in comparison to the bare theaflavin (Tf). The nanoconjugate is prepared by following a one-step green synthesis ̶ a reaction between HAuCl4 and the aflavin at room temperature. AuNP@TfQ is characterized using particle size analysis, FESEM, UV-vis, FTIR, fluorescence, and X-ray photoelectron spectroscopytechniques. We assume that the enhanced anti-cancer effect of AuNP@TfQ appears due to the facile oxidation of the pristine theaflavin to its quinone derivative on the surface of AuNPs. The presence of quinone motif in AuNP@TfQ induces an increased level of ROS generation probably through the depolarization of mitochondria and resulted in the caspase-mediated apoptotic cell death which may hold the potential for a "magic bullet"-mediated ovarian cancer treatment.

Ethylenediamine assisted functionalization of self-organized poly (d, l-lactide-co-glycolide) patterned surface to enhance cancer cell isolation.

Protein functionalized micro-scale patterned structures are developed using a biocompatible polymer PLGA (poly (d, l-lactide-co-glycolide)) via thin film dewetting and by step-wise chemical conjugations with EDA (ethylenediamine) and anti-EpCAM (Epithelial Cell Adhesion Molecule) antibodies to target the epithelial cell adhesion molecules of cancer cells. The effectiveness of such protein functionalized patterned surface is checked through cell isolation process using blood samples spiked with different cancer cells such as MCF-7, A549, MDA-MB-231. An efficient capture yield of 92% is obtained with MCF-7 cells over a two hour incubation time. The study demonstrates the effects of cell concentration and incubation time on the binding of cancer cells to the modified patterned surfaces. For the first time, a simple and inexpensive method is reported to fabricate functionalized PLGA patterned surface for an efficient isolation of cancer cells from diluted blood samples. The method shows the potential to be used as an effective platform for the development of an improved circulating tumor cell (CTC) isolation device from the clinical blood sample.

A novel approach to fabricate dye-encapsulated polymeric micro- and nanoparticles by thin film dewetting technique.

A new method is reported for fabrication of polymeric micro- and nanoparticles from an intermediate patterned surface originated by dewetting of a polymeric thin film. Poly (d, l-lactide-co-glycolide) or PLGA, a biocompatible polymer is used to develop a thin film over a clean glass substrate which dewets spontaneously in the micro-/nano-patterned surface of size range 50nm to 3.5µm. Since another water-soluble polymer, poly vinyl alcohol (PVA) is coated on the same glass substrate before PLGA thin film formation, developed micro-/nano-patterns are easily extracted in water in the form of micro- and nanoparticle mixture of size range 50nm to 3.0µm. This simplified method is also used to effectively encapsulate a dye molecule, rhodamine B inside the PLGA micro-/nanoparticles. The developed dye-encapsulated nanoparticles, PLGA-rhodamine are separated from the mixture and tested for in-vitro delivery application of external molecules inside human lung cancer cells. For the first time, the use of thin film dewetting technique is reported as a potential route for the synthesis of polymeric micro-/nanoparticles and effective encapsulation of external species therein.