Development of nanotechnology-based drug delivery and imaging system to the white adipose tissue vasculature using Wistar Rat Model

Philosophiae Doctor - PhDObesity is a complex metabolic disease of excessive fat accumulation. It is a worldwide epidemic affecting billions of people and its pharmacological management is hampered by drug toxicity and undesirable side effects. Therefore, a need still exists for the development of safe medication for treatment of obesity. Nanotechnology involves the use of small particles at atomic and molecular scale. It has application in medical diagnostics, drug delivery and molecular imaging. Various nanoparticles (NPs) functionalized with different biomolecules have been successfully used in many therapeutic and research applications due to their versatility, ease of chemical synthesis, low toxicity and unique properties. Examples of NPs used in this study are Gold nanoparticles (GNPs) and Quantum dots (QDs). GNPs and QDs are extensively used as drug delivery, labelling and imaging tools in biomedical research. Nanotechnology offers a new potential useful avenue for solving the problem of toxicity of anti-obesity drugs. This could be achieved through targeted drug delivery. In this study, rats were fed a high fed diet (HFD) to induce obesity. The streptavidin conjugated GNPs and QDs were functionalized with biotinylated adipose-homingpeptide (AHP) and/or anti-obesity drug (Gallic acid). Functionalization was characterized using agarose gel electrophoresis, UV-vis spectroscopy and transmission electron microscopy. The binding-specificity and targeting ability of AHP was evaluated in vitro and in vivo. The apoptotic effect of AHP functionalized-drug loaded GNPs (AHP-GA-GNPs) was tested in vitro using APOPercentage TM and Caspase-3 activation assays. The in vitro data indicated that the binding was specific to prohibitin (PHB) expressing cells (MCF-7 and Caco-2), and that the binding was temperature dependent. PHB was confirmed as a target for AHP after overlaying AHP-FITC and anti-prohibitin antibody staining. Cellular uptake was detected on the cells treated with AHP-functionalized NPs as compared to unfunctionalized NPs. The GA and AHP-GA-GNPs reduced cellular viability and induced apoptosis through activation of Caspase-3. The Ex-vivo studies using primary endothelial cells (ECs) isolated from the WAT of lean and obese Wistar rats showed that the binding of AHP was receptor mediated, and specific to receptors differentially expressed in ECs from obese WAT. The in vivo studies showed that, treatment of obese rats with AHP-functionalized NPs resulted in targeted delivery of the NPs to the WAT as compared to those treated with unfunctionalized NPs. Qualitative analysis using fluorescence microscopy and IVIS Luminar XR, live-imaging system showed that the unfunctionalized NPs accumulated mostly in the organs of the reticuloendothelial system, namely: liver, spleen, lungs and kidneys. In contrast, AHP-functionalized NPs accumulated mostly in the WATs as compared to the rest of the organs of the obese rats. Uptake and binding of the NPs to the tissues was quantitatively confirmed by the inductive coupled plasma-optical emission spectroscopy (ICP-OES). In conclusion, this study reports the 1) successful functionalization of GNPs and QDs with AHP, 2) use of AHP-functionalized GNPs and QDs as delivery and imaging agents to the WAT, and 3) potential use of AHP-functionalized drug-loaded GNPs in the treatment of obesity

Peptide-functionalized quantum dots for potential applications in the imaging and treatment of obesity

BACKGROUND: Obesity is a worldwide epidemic affecting millions of people. The current pharmacological treatment of obesity remains limited and ineffective due to drugs’ undesirable side effects. Hence, there is a need for novel or improved strategies for long-term therapies that will help prevent the disease progression into other chronic diseases. Nanotechnology holds the future for the treatment of obesity because of its versatility, as shown by improved drug efficiency and safety in cancer clinical trials. Nano-based drug delivery systems could potentially do the same for obesity through targeted drug delivery. This study investigated the use of peptide-functionalized quantum dots (QDs) for the imaging of prohibitin (PHB)-expressing cells in vitro and in diet-induced obese rats, which could potentially be used as nanocarriers of antiobesity drugs. METHODS: Cadmium (Cd)-based QDs were functionalized with an adipose homing peptide (AHP) and injected intravenously into lean and obese Wistar rats. Biodistribution of the QDs was analyzed by an IVIS® Lumina XR imaging system and inductively coupled plasma optical emission spectroscopy (ICP-OES). For in vitro studies, PHB-expressing (Caco-2 and MCF-7) and non-PHB-expressing (KMST-6 and CHO) cells were exposed to either unfunctionalized QDs (QD625) or AHP-functionalized QDs (AHP-QD625) and analyzed by fluorescence microscopy. RESULTS: AHP-QD625 accumulated significantly in PHB-expressing cells in vitro when compared with non-PHB-expressing cells. In vivo data indicated that QD625 accumulated mainly in the reticuloendothelial system (RES) organs, while the AHP-QD625 accumulated mostly in the white adipose tissues (WATs). CONCLUSION: AHP-functionalized QDs were successfully and selectively delivered to the PHB-expressing cells in vitro (Caco-2 and MCF-7 cells) and in the WAT vasculature in vivo. This nanotechnology-based approach could potentially be used for dual targeted drug delivery and molecular imaging of adipose tissues in obese patients in real time

Imino-phospine palladium (II) and platinum (II) complexes: Synthesis, molecular structures and evaluation as antitumor agents

The imino-phosphine ligands L1 and L2 were prepared via condensation reaction of 2-(diphenylphosphino) benzaldehyde with substituted anilines and obtained in very good yields. An equimolar reaction of L1 and L2 with either PdCl2(cod) or PtCl2(cod) gave new palladium(II) and platinum(II) complexes 1–4. The compounds were characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy. The molecular structures of 2, 3 and 4 were confirmed by X-ray crystallography. All the three molecular structures crystallized in monoclinic C2/c space system. The coordination geometry around the palladiumand platinumatoms in respective structures exhibited distorted square planar geometry at the metal centers. The complexes were evaluated in vitro for their cytotoxic activity against human breast (MCF-7) and human colon (HT-29) cancer cells, and they exhibited growth inhibitory activities and selectivity that were superior to the standard compound cisplatin.Web of Scienc

Synthesis, Characterization and In Vitro Antibacterial Evaluation of Pyrenacantha grandiflora Conjugated Silver Nanoparticles

In the present study, silver nanoparticles (AgNPs) were synthesized using both the chemical and biological methods and conjugated with Pyrenacantha grandiflora extracts. These were then characterized and evaluated for antimicrobial activities against multi-drug resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumonia, and Escherichia coli. Nanoparticles were analyzed with UV-visible spectrophotometer, transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX). Silver nanoparticles, P. grandiflora extracts, and the conjugates were also analyzed with Fourier transform infrared spectroscopy (FTIR). As a result, quasi-sphere-shaped AgNPs with sizes ranging from 5 to 33 nm and spherically shaped AgNPs with sizes ranging from 3 to 25 nm were formed from chemical and biological synthesis, respectively. A well diffusion assay showed that the activity of silver nanoparticles was most improved with acetone extract against all tested bacteria with diameters in the range of 19–24 mm. The lowest MIC value of 0.0063 mg/mL against MRSA was observed when biologically synthesized AgNPs were conjugated with acetone and water extracts. Chemically synthesized silver nanoparticles showed the lowest MIC value of 0.0063 mg/mL against E. coli when conjugated with acetone and methanol extracts. This study indicates that silver nanoparticles conjugated with P. gandiflora tubers extracts exhibit strong antibacterial activities against multi-drug resistant bacterial pathogens. Therefore, biosynthesized conjugates could be utilized as antimicrobial agents for effective disease management due to the synergistic antibacterial activity that was observed