Natural polysaccharide functionalized gold nanoparticles as biocompatible drug delivery carrier

Multifaceted activities of plant gum synthesised platinum nanoparticles: catalytic, peroxidase, PCR enhancing and antioxidant activities

A single pot, green method for platinum nanoparticles (Pt NP) production was devised with gum ghatti (Anogeissus latifolia). Analytical tools: ultraviolet-visible (UV-vis), dynamic light scattering, zeta potential, transmission electron microscope, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy were employed. Wide continuous UV-vis absorption and black solution colouration proved Pt NP formation. Face-centred cubic crystalline structure of NP was evidenced from XRD. NPs formed were nearly spherical with a mean particle size of 3 nm. NP demonstrated a myriad of properties including catalytic, peroxidase, polymerase chain reaction (PCR) enhancing and antioxidant activities. Catalytic action of NP was probed via NaBH4 reduction of arsenazo-III dye. NP displayed considerable peroxidase activity via catalysis of 3, 3', 5, 5'-tetramethylbenzidine oxidation by H2O2. NP showed exceptional stability towards varying pH (3-11), temperature (25-100°C), salt concentration (0-100 mM) and storage time duration (0-12 months). In comparison with horse radish peroxidase, its applicability as an artificial peroxidase is advantageous. NP caused a two-fold enhancement in PCR yield at 0.4 nM. Also showed significant 1', 1' diphenyl picryl-hydrazyle scavenging (80.1%) at 15 µg/mL. Author envisages that the biogenic Pt NP can be used in a range of biological and environmental applications.

Impact of critical micelle concentration of macroRAFT agents on the encapsulation of colloidal Au nanoparticles

HYPOTHESIS

Reversible addition fragmentation chain transfer (RAFT) - assisted encapsulating emulsion polymerization (REEP) has received considerable attention as an efficient strategy to prepare colloidal stable shell@core nanoparticles. Generally, amphipathic macroRAFT agents are used but the effect of working above or below the critical micelle concentration (CMC) of macroRAFT agents needs to be addressed. Hence, it is necessary to understand if this parameter has an impact not only on the stability of the colloids but also on the molecular mass of the polymer shell.

METHODS

Here, the CMC of three different macroRAFT agent was determined and the effect of macroRAFT agents concentration on the colloidal stability of gold nanoparticles coated with macroRAFT agents (macroRAFT@Au) assessed. The subsequent chain extension from macroRAFT@Au NPs, resulting in encapsulated Au nanoparticles (copolymer@Au), has also been systematically studied.

FINDINGS

Using the REEP approach it was possible to obtain stable encapsulated Au NPs. Moreover, this strategy opens the possibility of adjusting the macroRAFT agents concentration to tune the length of the polymer chains grown around Au cores which is of major interest for the design of biosensors based on responsive polymer shells, such as pH, temperature and photoluminescence quenching.

Fucoidan-Stabilized Gold Nanoparticle-Mediated Biofilm Inhibition, Attenuation of Virulence and Motility Properties in Pseudomonas aeruginosa PAO1

The emergence of antibiotic resistance in Pseudomonas aeruginosa due to biofilm formation has transformed this opportunistic pathogen into a life-threatening one. Biosynthesized nanoparticles are increasingly being recognized as an effective anti-biofilm strategy to counter P. aeruginosa biofilms. In the present study, gold nanoparticles (AuNPs) were biologically synthesized and stabilized using fucoidan, which is an active compound sourced from brown seaweed. Biosynthesized fucoidan-stabilized AuNPs (F-AuNPs) were subjected to characterization using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission transmission electron microscopy (FE-TEM), dynamic light scattering (DLS), and energy dispersive X-ray diffraction (EDX). The biosynthesized F-AuNPs were then evaluated for their inhibitory effects on P. aeruginosa bacterial growth, biofilm formation, virulence factor production, and bacterial motility. Overall, the activities of F-AuNPs towards P. aeruginosa were varied depending on their concentration. At minimum inhibitory concentration (MIC) (512 µg/mL) and at concentrations above MIC, F-AuNPs exerted antibacterial activity. In contrast, the sub-inhibitory concentration (sub-MIC) levels of F-AuNPs inhibited biofilm formation without affecting bacterial growth, and eradicated matured biofilm. The minimum biofilm inhibition concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were identified as 128 µg/mL. Furthermore, sub-MICs of F-AuNPs also attenuated the production of several important virulence factors and impaired bacterial swarming, swimming, and twitching motilities. Findings from the present study provide important insights into the potential of F-AuNPs as an effective new drug for controlling P. aeruginosa-biofilm-related infections.

DM1 Loaded Ultrasmall Gold Nanoparticles Display Significant Efficacy and Improved Tolerability in Murine Models of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide with poor prognosis and limited options for treatment. Life expectancy after diagnosis is short; the currently available treatments are not well tolerated and have limited clinical benefit. There is a clear unmet clinical need for the development of new treatments. In this study, ultrasmall, 2 nm gold core nanoparticles (MidaCore) conjugated with the potent maytansine analogue DM1 (MTC-100038) were assessed as a systemic nanomedicine for the treatment of hepatocellular carcinoma. The platform improved overall tolerability of DM1, permitting ∼3-fold higher levels of drug to be administered compared to free drug. Dose for dose, MTC-100038 also facilitated delivery of ∼2.0-fold higher ( p = 0.039) levels of DM1 to the tumor compared to free DM1. MTC-100038 produced significant efficacy (tumor growth index ∼102%; p = <0.0001), in several murine xenograft models of HCC, and was superior to both free DM1 and the current standard of care, sorafenib. Furthermore, MTC-100038 displayed potent (nM) in vitro activity in various HCC primary patient derived cell lines and across various other different cancer cell types. These data demonstrate the potential of MidaCore nanoparticles to enhance tumor delivery of cytotoxic drugs and indicate MTC-100038 is worthy of further investigation as a potential treatment for HCC and other cancer types.

Green tea extract-assembled nanoclusters for combinational photothermal and chemotherapy

Gold nanoclusters were developed by a “green chemistry” method, wherein green tea acts as a reducing agent, co-polymerization site and stabilizer.

Green synthesis of polysaccharide-based inorganic nanoparticles and biomedical aspects

Biologically mediated inorganic nanoparticles (NPs) are considered as a green, cheap, and environmental-friendly materials, which connect the nanotechnology and biomedical sciences. Metallic NPs such as gold and silver NPs, synthesized using natural materials are an important branch of inorganic NPs with catalytic functionalities and a diverse range of biomedical applications such as antimicrobial application. Polysaccharides are excellent candidates to stabilize and control the size of NPs during the synthesis process. These polymers possess multiple binding sites, which facilitate attachment to the metal surface. As a result, polysaccharides can effectively create an organic-inorganic network of the metal NPs and confer a significant protection against aggregation and chemical modifications. This chapter discusses the methods of the preparation of polysaccharide-mediated NPs and reviews various types and diverse applications for these novel materials.

Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields

The prospective uses of tree gum polysaccharides and their nanostructures in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. In addition to extensive applications of tree gums in food, there are substantial non-food applications of these commercial gums, which have gained widespread attention due to their availability, structural diversity and remarkable properties as 'green' bio-based renewable materials. Tree gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. This review focuses on non-food applications of several important commercially available gums (arabic, karaya, tragacanth, ghatti and kondagogu) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, environmental bioremediation, bio-catalysis, biosensors, coordination complexes of metal-hydrogels, and for antimicrobial and biomedical applications. Furthermore, polysaccharides acquired from botanical, seaweed, animal, and microbial origins are briefly compared with the characteristics of tree gum exudates.

Evaluation of Paeonia emodi and its gold nanoparticles for cardioprotective and antihyperlipidemic potentials

Paeonia emodi Wall. ex Royle is an important member of family Paeoniaceae and folklorically used for constipation, hysteria, respiratory diseases, epilepsy and cardiac diseases like hypertension, palpitations, congestive heart failure and atherosclerosis. In the present study, ethyl acetate fraction of P. emodi (Pe.EA) was subjected to column chromatography to obtain sub- fractions. These sub-fractions were screened for their cardioprotective activity in isoproterenol hydrochloride (ISO) induced myocardial infarction (MI) in mice. The most active fraction Pe. EA 40 was used for its gold nanoparticles synthesis (Pe.EA 40-AuNPs). Pe.EA 40 and Pe.EA 40-AuNPs were investigated for their cardioprotective, antihyperlipidemic, DNA fragmentation assay and histopathological study. Pe.EA 40 (80 mg/kg body weight) significantly reduced the serum levels of Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Lactate Dehydrogenase (LDH), Creatine Phosphokinase (CPK) to 66.07 ± 1.54, 77.08 ± 1.79, 84.86 ± 1.34 and 265.34 ± 4.34 IU/L respectively as compared to ISO treated group. Pe.EA 40-AuNPs (40 mg/kg) reduced the levels of ALT, AST, CPK and LDH to 60.74 ± 2.79, 75.47 ± 1.67, 80.48 ± 2.64 and 247.54. ± 5.57 IU/L respectively. A significant reduction was observed in lipid profile, protection in DNA damage and restoration of histopathological changes as compared to ISO treated group. Based on the results, it can be suggested that preparation of Pe.EA 40-AuNPs enhances the therapeutic potential of plant extract for the treatment of atherosclerosis and MI.

Preparation, Characterization and Application of Polysaccharide-Based Metallic Nanoparticles: A Review

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction and stabilization of MNPs. Considerable research has been directed toward investigating polysaccharide-based metallic nanoparticles (PMNPs) through host⁻guest strategy. In this review, approaches of preparation, including top-down and bottom-up approaches, are presented and compared. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, dynamic light scattering, UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering are discussed in detail. Besides, the applications of PMNPs in the field of wound healing, targeted delivery, biosensing, catalysis and agents with antimicrobial, antiviral and anticancer capabilities are specifically highlighted. The controversial toxicological effects of PMNPs are also discussed. This review can provide significant insights into the utilization of polysaccharides as the hosts to synthesize MPNs and facilitate their further development in synthesis approaches, characterization techniques as well as potential applications.

Peptide grafted and self-assembled poly(γ-glutamic acid)-phenylalanine nanoparticles targeting camptothecin to glioma

Aim: To synthesize cRGDfK peptide conjugated poly(γ-glutamic acid)-phenylalanine nanoparticles to improve the therapeutic efficacy of camptothecin (CPT) against glioblastoma multiforme. Methods: Peptide-conjugated, drug-loaded nanoparticles (cRGDfK-conjugated camptothecin-loaded PGA–PA nanoparticles [RCPN]) were prepared and physico-chemically characterized using different techniques. Nanoparticles were evaluated for in vitro anticancer activity, cellular uptake, induction of apoptosis and wound healing cell migration against U87MG human glioblastoma cells. Results: RCPN, with a particle size of <100 nm and 65% CPT encapsulation efficiency, exhibited a dose- and time-dependent cytotoxicity to glioblastoma cells. Compared with native CPT or unconjugated nanoparticles, RCPN induced apoptosis, increased reactive oxygen species generation and inhibited U87MG cell migration. Conclusion: cRGDfK-mediated and amphiphilic copolymer-based nanomedicines represent a new approach for improved delivery of anticancer drugs to and treatment of glioblastoma multiforme.

RhoA inhibits apoptosis and increases proliferation of cultured SPCA1 lung cancer cells

The Rho kinase pathway has previously been reported to possess a close relationship with the growth, migration and invasion of lung cancer cells. However, the molecular mechanisms underlying the effects of this pathway on lung cancer cells are still elusive. The aim of the present study was to investigate the effects and underlying molecular mechanisms of Ras homolog family member A (RhoA) on the proliferation and apoptosis of SPCA1 lung carcinoma cells. Stable SPCA1 lung cancer cell lines, in which RhoA expression was silenced by small interfering RNA, were isolated following Geneticin screening. Inhibition of RhoA expression significantly decreased the proliferation of SPCA1 lung cancer cells, whereas apoptosis was significantly increased (P<0.01) as determined by the MTS tetrazolium assay and flow cytometry analysis, respectively. At the molecular level, knockdown of RhoA resulted in the significant activation of caspase-3 (P<0.01), and a significant reduction in the levels of phosphorylated signal transducer and activator of transcription (phospho-STAT3; P<0.01), as determined by western blotting. The results suggested that RhoA knockdown prevents cell proliferation and induces apoptosis in SPCA1 lung cancer cells. Furthermore, the underlying mechanisms responsible for these effects may include the activation of caspase-3 and the reduction of phospho-STAT3 levels.

Recent advances in drug delivery strategies for improved therapeutic efficacy of gemcitabine

Gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) is an efficacious anticancer agent acting against a wide range of solid tumors, including pancreatic, non-small cell lung, bladder, breast, ovarian, thyroid and multiple myelomas. However, short plasma half-life due to metabolism by cytidine deaminase necessitates administration of high dose, which limits its medical applicability. Further, due to its hydrophilic nature, it cannot traverse cell membranes by passive diffusion and, therefore, enters via nucleoside transporters that may lead to drug resistance. To circumvent these limitations, macromolecular prodrugs and nanocarrier-based formulations of Gemcitabine are gaining wide recognition. The nanoformulations based approaches by virtue of their controlled release and targeted delivery have proved to improve bioavailability, increase therapeutic efficacy and reduce adverse effects of the drug. Furthermore, the combination of Gemcitabine with other anticancer agents as well as siRNAs using nanocarriers has also been investigated in order to enhance its therapeutic potential. This review deals with challenges and recent advances in the delivery of Gemcitabine with particular emphasis on macromolecular prodrugs and nanomedicines.

Ultrafast synthesis of stabilized gold nanoparticles using aqueous fruit extract of Limonia acidissima L. and conjugated epirubicin: targeted drug delivery for treatment of breast cancer

Green synthesis of AuNPs using extract ofLimonia acidissimaL. as a reducing agent. Epirubicin was successfully loaded on folic acid–AuNPs. This formulation revealed better site specific delivery of epirubicin to MCF-7 cells.