Susheel Kumar Nethi

Graphene Oxides Show Angiogenic Properties

Angiogenesis, a process resulting in the formation of new capillaries from the pre-existing vasculature plays vital role for the development of therapeutic approaches for cancer, atherosclerosis, wound healing, and cardiovascular diseases. In this report, the synthesis, characterization, and angiogenic properties of graphene oxide (GO) and reduced graphene oxide (rGO) have been demonstrated, observed through several in vitro and in vivo angiogenesis assays. The results here demonstrate that the intracellular formation of reactive oxygen species and reactive nitrogen species as well as activation of phospho-eNOS and phospho-Akt might be the plausible mechanisms for GO and rGO induced angiogenesis. The results altogether suggest the possibilities for the development of alternative angiogenic therapeutic approach for the treatment of cardiovascular related diseases where angiogenesis plays a significant role.

Accelerating the clearance of mutant huntingtin protein aggregates through autophagy induction by europium hydroxide nanorods

Autophagy is one of the well-known pathways to accelerate the clearance of protein aggregates, which contributes to the therapy of neurodegenerative diseases. Although there are numerous reports that demonstrate the induction of autophagy with small molecules including rapamycin, trehalose and lithium, however, there are few reports mentioning the clearance of aggregate-prone proteins through autophagy induction by nanoparticles. In the present article, we have demonstrated that europium hydroxide [Eu(III)(OH)3] nanorods can reduce huntingtin protein aggregation (EGFP-tagged huntingtin protein with 74 polyQ repeats), responsible for neurodegenerative diseases. Again, we have found that these nanorods induce authentic autophagy flux in different cell lines (Neuro 2a, PC12 and HeLa cells) through the expression of higher levels of characteristic autophagy marker protein LC3-II and degradation of selective autophagy substrate/cargo receptor p62/SQSTM1. Furthermore, depression of protein aggregation clearance through the autophagy blockade has also been observed by using specific inhibitors (wortmannin and chloroquine), indicating that autophagy is involved in the degradation of huntingtin protein aggregation. Since [Eu(III)(OH)3] nanorods can enhance the degradation of huntingtin protein aggregation via autophagy induction, we strongly believe that these nanorods would be useful for the development of therapeutic treatment strategies for various neurodegenerative diseases in near future using nanomedicine approach.

Hyperglycaemia Enhances Nitric Oxide Production in Diabetes: A Study from South Indian Patients

Background We have previously reported that increased glucose levels were associated with higher serum nitric oxide (NO) levels in fructose-fed insulin resistant rats. However, the relationship between hyperglycemia and serum NO level was not clear. Therefore, the present study was designed to find the association between hyperglycemia and serum NO levels in Type 2 diabetic (T2DM) patients and T2DM with cardiovascular complication. Methods Endothelial cells (HUVEC) were treated with of D-glucose (10-100mM), and NO levels and NOS gene expression was measured. Hyperglycaemia was induced in Sprague-Dawley rats, and serum NO levels were measured after 8 weeks. For clinical evaluation, five groups of patients were recruited: Control (CT, n=48), Type 2 diabetes (T2DM, n=26), T2DM with hypertension (DMHT, n=46), Coronary artery diseases (CAD, n=29) and T2DM with coronary artery diseases (DMCD, n=38). NO (nitrite + nitrate) levels were measured from human serum. Results We found a significant (p<0.05) and dose-dependent increase in NO levels in HUVEC cells after 4 hours of high glucose exposure. eNOS and iNOS gene expression was increased in HUVEC cells after different concentrations and time periods of glucose treatment. We also observed significant (149.1±25μM, p<0.01) increase in serum NO levels in hyperglycaemic rats compared to control (76.6±13.2μM). Serum NO level was significantly higher in T2DM (111.8 μM (81.7-122.4), p<0.001) and DMCD patients ((129.4 μM (121.2-143.5), p <0.001) but not in CAD patients (76.4 μM (70.5-87)), as compared to control (68.2 μM (56.4-82.3)). We found significantly lower NO levels (83.5 μM (60.5-122.9)) in subjects suffering from diabetes since more than 5 years, compared to subjects (115.3 μM (75.2-127.1), p<0.001) with less than 5 years. Conclusion In conclusion, high NO levels were observed in South Indian diabetic patients. Higher glucose levels in serum might be responsible for activation of endothelial cells to enhance NO levels.

Electrospun polycaprolactone (PCL) scaffolds embedded with europium hydroxide nanorods (EHNs) with enhanced vascularization and cell proliferation for tissue engineering applications

Electrospun polycaprolactone (PCL) tissue engineering scaffolds have been developed and used for a wide range of tissue engineering applications, where successful incorporation and conservation of the therapeutic activity of the embedded nanoparticles into scaffolds is critically needed for effective tissue engineering. Incorporation of pro-angiogenic nanomaterials to promote vascularization is a novel approach. Our group has well-demonstrated the potent pro-angiogenic properties of europium hydroxide nanorods (EHNs) using in vitro and in vivo systems. In the present study, electrospun PCL tissue engineering scaffolds containing EHNs were fabricated and characterized for various morphological and physico-chemical properties. Furthermore, biological studies showed enhanced cell growth and a greater density of endothelial cells grown on the scaffolds incorporated with EHNs (PCL-EHNs). The PCL-EHNs also exhibited good hemo-compatibility towards blood cells. Fluorescence microscopy and SEM observations showed good endothelial cell adhesion over these scaffolds. The PCL-EHNs demonstrated augmented growth of blood vessels in an in vivo chick embryo angiogenesis model. Furthermore, protein expression studies illustrated promoted angiogenesis of HUVECs on scaffolds in a VEGFR2/Akt mediated signaling cascade. Together, the above observations strongly suggest potent applications of EHN-incorporated PCL scaffolds in promoting angiogenesis/vascularization and their effective use in tissue engineering and vascular disease therapy.

Design, synthesis and characterization of doped-titanium oxide nanomaterials with environmental and angiogenic applications

Since the last decade, the metal composite nanostructures have evolved as promising candidates in regard to their wide applications in the fields of science and engineering. Recently, several investigators identified the titanium based nanomaterials as excellent agents for multifunctional environmental and biomedical applications. In this perspective, we have developed a series of zinc-doped (2 and 5%) titanium oxide-based nanomaterials using various reaction conditions and calcination temperatures (TZ1-TZ3: calcined at 500°C, TZ4-TZ6: calcined at 600°C and TZ7-TZ9: calcined at 700°C). The calcined materials (TZ1 to TZ9) were thoroughly analyzed by several physico-chemical characterization methods. The increase of the calcination temperature results in significant changes of the textural properties of the nanostructured materials. In addition, the increase of the calcination temperature leads to the formation of anatase/rutile mixtures with higher quantity of rutile. Furthermore, incorporation of zinc changes the morphology of the obtained nanoparticles. The materials were studied in the photodegradation of methylene blue observing that materials calcined at lower temperatures (TZ1-TZ3) have higher photocatalytic activity than those of the materials calcined at 600°C (TZ4-TZ6), rutile-based systems TZ7-TZ9 are not active. Based on the background literature of titanium and zinc based nanostructures in therapeutic angiogenesis, we have explored the pro-angiogenic properties of these materials using various in vitro and in vivo assays. The zinc-doped titanium dioxide nanostructures (TZ5 and TZ6) exhibited increased cell viability, proliferation, enhanced S-phase cell population, increased pro-angiogenic messengers (ROS: reactive oxygen species and NO: nitric oxide) production and promoted in vivo blood vessel formation in a plausible mechanistic p38/STAT3 dependent signaling cascade. Altogether, the results of the present study showcase these zinc doped-titanium oxide nanoparticles as promising candidates for environmental (water-remediation) and therapeutic angiogenic applications.

Green Synthesized Gold Nanoparticles for Future Biomedical Applications

Nanobiotechnology is an emerging field of biological and engineering sciences. The design and development of green chemistry approach for the synthesis of biocompatible nanoparticles is always better selection due to eco-friendliness. The green chemistry approach for the synthesis of metal nanoparticles has several advantages (simple, safer, energy efficient, fast, mostly one-pot processes, inexpensive, and less toxic routes toward synthesis) over conventional synthetic procedures. Among various biologically synthesized metal nanoparticles, noble nanoparticles (gold, silver and platinum) especially gold nanoparticles (AuNPs) are exceptionally attractive in biomedical application due to presence of unusual physicochemical properties, ease of synthesis and surface modification in the nanoscale range, biocompatibility, and several other advantages. Recently, several researchers including our group have intensely focused to explore the green synthesis and potential applications of AuNPs in biology and medicine. In this chapter, we discuss about the (i) synthesis of AuNPs using rational utilization of various bioresources, (ii) their prospective applications toward various disease therapy, (iii) in vitro and in vivo toxicity, (iv) biodistribution studies, and (v) future challenges and opportunities.

Investigation of the role of nitric oxide driven angiogenesis by zinc oxide nanoflowers

Angiogenesis is a vital process that deals with the generation of new blood vessels from pre-existing vasculature and is well known to regulate various physiological as well as pathophysiological processes. We demonstrated that zinc oxide nanoflowers (ZONF) exhibited pro-angiogenic properties in endothelial cells through the production of intracellular reactive oxygen species (ROS), especially H2O2 (hydrogen peroxide). The immense importance of angiogenesis in ischemic and cardiovascular diseases highlights an urgent need to comprehend the detailed molecular mechanisms underlying the ZONF induced angiogenesis process. However, the exact mechanism and signaling pathways behind nanoflowers mediated angiogenesis still remain unclear. In the present study, we report that ZONF induce angiogenesis through MAPK/Akt/eNOS mediated nitric oxide formation, which further acts in a cGMP dependent manner. We strongly believe that exploration of the molecular mechanism and signaling pathways of ZONF driven angiogenesis would be helpful for the advancement of alternative and efficient treatment strategies for ischemic and cardiovascular diseases using a nanomedicine approach.

Functionalized nanoceria exhibit improved angiogenic properties

The growth of new blood vessels from the pre-existing vasculature known as angiogenesis has a vital role in various physiological and pathological processes. In the present study, we demonstrate the pro-angiogenic properties of functional nanoconjugates of organosilane functionalized cerium oxide (CeO2) nanoparticles (nanoceria). Aqueous dispersible CeO2 and trivalent metal (samarium) ion-doped CeO2 (SmCeO2) nanoparticles conjugated with hydrophilic biocompatible and antifouling (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl)triethoxysilane moieties were prepared. These functional nanoconjugates were prepared via an in situ synthesis and functionalization procedure using an ammonia-induced ethylene glycol-assisted precipitation method. The prepared nanoconjugates were thoroughly characterized using various physico-chemical techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, dynamic light scattering (DLS), Fourier-transform infrared (FTIR) spectroscopy, 13C high-resolution solid-state nuclear magnetic resonance (NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The pro-angiogenic properties of the prepared nanoconjugates were evaluated by employing various angiogenesis assays (in vitro and in vivo). The results of the present study illustrate that the functional nanoconjugates of SmCeO2 triggered endothelial cell proliferation and induced the growth of blood vessels in a chick embryo. The enhanced expression of pro-angiogenic markers (p38 MAPK/HIF-1α) by these functional nanoconjugates might be a plausible signaling mechanism underlying their pro-angiogenic properties. Considering all the observations, we believe that (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl)triethoxysilane conjugated SmCeO2 nanoparticles could be developed as potential candidates for the treatment of cardiovascular, ischemic and ocular diseases where angiogenesis is the principal phenomenon.

Biomedical and drug delivery applications of functionalized inorganic nanomaterials

Nanotechnology using inorganic metal nanoparticles plays an important role in altering the scenario of disease diagnosis and therapy in modern biomedical research. In recent decades, extensive research produces several nanomedicines among which functionalized inorganic nanomaterials, especially gold, silver and silica nanoparticles are of great attraction for various medicinal applications such as drug delivery, cancer therapy, tissue engineering, bio-imaging etc. These functionalized inorganic nanomaterials possess unique physico-chemical properties, high stability and they are mostly biocompatible. Moreover, the large surface area of these nanomaterials facilitates their easier conjugation with therapeutic molecules, dyes and fluorescent probes making them excellent delivery vehicles and diagnostic agents. This book chapter provides the overview of recent advancement of functionalized inorganic nanomaterials (gold, silver and silica) for their versatile biomedical applications for different diseases. Considering clinical potential application, we discuss the pharmacokinetics, bio-distribution and clearance of these functionalized nanomaterials in detail. Furthermore, the status of gold, silver and silica nanoparticles in clinical studies is briefly illustrated. Finally, we conclude with challenges and future prospects of functionalized inorganic nanomaterials for their biomedical applications.