Multifunctional block copolymer nanocarriers for co-delivery of silver nanoparticles and curcumin: Synthesis and enhanced efficacy against tumor cells

Natural and Synthetic Polymers for Biomedical and Environmental Applications

Natural and synthetic polymers are a versatile platform for developing biomaterials in the biomedical and environmental fields. Natural polymers are organic compounds that are found in nature. The most common natural polymers include polysaccharides, such as alginate, hyaluronic acid, and starch, proteins, e.g., collagen, silk, and fibrin, and bacterial polyesters. Natural polymers have already been applied in numerous sectors, such as carriers for drug delivery, tissue engineering, stem cell morphogenesis, wound healing, regenerative medicine, food packaging, etc. Various synthetic polymers, including poly(lactic acid), poly(acrylic acid), poly(vinyl alcohol), polyethylene glycol, etc., are biocompatible and biodegradable; therefore, they are studied and applied in controlled drug release systems, nano-carriers, tissue engineering, dispersion of bacterial biofilms, gene delivery systems, bio-ink in 3D-printing, textiles in medicine, agriculture, heavy metals removal, and food packaging. In the following review, recent advancements in polymer chemistry, which enable the imparting of specific biomedical functions of polymers, will be discussed in detail, including antiviral, anticancer, and antimicrobial activities. This work contains the authors' experimental contributions to biomedical and environmental polymer applications. This review is a vast overview of natural and synthetic polymers used in biomedical and environmental fields, polymer synthesis, and isolation methods, critically assessessing their advantages, limitations, and prospects.

Synthesis approaches of amphiphilic copolymers for spherical micelle preparation: application in drug delivery

The formation of polymeric micelles in aqueous environments through the self-assembly of amphiphilic polymers can provide a versatile platform to increase the solubility and permeability of hydrophobic drugs and pave the way for their administration. In comparison to various self-assembly-based vehicles, polymeric micelles commonly have a smaller size, spherical morphology, and simpler scale up process. The use of polymer-based micelles for the encapsulation and carrying of therapeutics to the site of action triggered a line of research on the synthesis of various amphiphilic polymers in the past few decades. The extended knowledge on polymers includes biocompatible smart amphiphilic copolymers for the formation of micelles, therapeutics loading and response to external stimuli, micelles with a tunable drug release pattern, etc. Different strategies such as ring-opening polymerization, atom transfer radical polymerization, reversible addition-fragmentation chain-transfer, nitroxide mediated polymerization, and a combination of these methods were employed to synthesize copolymers with diverse compositions and topologies with the proficiency of self-assembly into well-defined micellar structures. The current review provides a summary of the important polymerization techniques and recent achievements in the field of drug delivery using micellar systems. This review proposes new visions for the design and synthesis of innovative potent amphiphilic polymers in order to benefit from their application in drug delivery fields.

Redox-Responsive Crosslinked Mixed Micelles for Controllable Release of Caffeic Acid Phenethyl Ester

We report the elaboration of redox-responsive functional micellar nanocarriers designed for triggered release of caffeic acid phenethyl ester (CAPE) in cancer therapy. Three-layered micelles, comprising a poly(ε-caprolactone) (PCL) core, a middle poly(acrylic acid)/poly(ethylene oxide) (PAA/PEO) layer and a PEO outer corona, were prepared by co-assembly of PEO₁₁₃-b-PCL₃₅-b-PEO₁₁₃ and PAA₁₃-b-PCL₃₅-b-PAA₁₃ amphiphilic triblock copolymers in aqueous media. The preformed micelles were loaded with CAPE via hydrophobic interactions between the drug molecules and PCL core, and subsequently crosslinked by reaction of carboxyl groups from PAA and a disulfide crosslinking agent. The reaction of crosslinking took place in the middle layer of the nanocarriers without changing the encapsulation efficiency (EE~90%) of the system. The crosslinked polymeric micelles (CPMs) exhibited superior structural stability and did not release CAPE in phosphate buffer (pH 7.4). However, in weak acidic media and in the presence of 10 mM reducing agent (dithiothreitol, DTT), the payload was released at a high rate from CPMs due to the breakup of disulfide linkages. The physicochemical properties of the nanocarriers were investigated by dynamic and electrophoretic light scattering (DLS and ELS) and atomic force microscopy (AFM). The rapid release of CAPE under intracellular-like conditions and the lack of premature drug release in media resembling the blood stream (neutral pH) make the developed CPMs a promising candidate for controllable drug release in the microenvironment of tumors.

Antiviral activity against Zika virus of a new formulation of curcumin in poly lactic-co-glycolic acid nanoparticles

OBJECTIVES

In the search of an effective antiviral formulation, the natural product curcumin (CUR) was encapsulated into poly(lactic-co-glycolic acid) nanoparticles, a non-toxic bioresorbable and biocompatible copolymer. The resulting CUR containing particles (PLGA-CUR NPs) were characterized and analysed for antiviral activity against Zika virus (ZIKV) infection.

METHODS

The PLGA-CUR NPs were characterized by Fourier transform infrared, differential scanning calorimetry, dynamic light scattering, scanning electron microscopy and thermogravimetric analysis and release profile. Cytotoxicity of PLGA-CUR and the antiviral activity against ZIKV were determined in Vero cells. The effect of PLGA-CUR NPs on viral RNA synthesis and protein expression was analysed by RT-qPCR and immunofluorescence staining, respectively.

KEY FINDINGS

The PLGA-CUR NPs showed an appropriate in vitro drug release profile. Our studies of the antiviral activity of PLGA-CUR NPs and CUR against ZIKV by virus yield reduction as well as viral RNA synthesis and protein expression have shown that PLGA-CUR formulation is more effective than free CUR to inhibit ZIKV infection of Vero cells.

CONCLUSIONS

Our results demonstrate for the first time the antiviral activity against ZIKV of PLGA nanoparticles charged with CUR, suggesting that PLGA-CUR NPs are promising candidates for a drug formulation against human pathogenic flaviviruses.

Amphiphilic polymeric nanoparticles encapsulating curcumin: Antioxidant, anti-inflammatory and biocompatibility studies

Oxidative stress and inflammation are two related processes common to many diseases. Curcumin is a natural compound with both antioxidant and anti-inflammatory properties, among others, that is recently being used as a natural occurring product alternative to traditional drugs. However, it has a hydrophobic nature that compromises its solubility in physiological fluids and its circulation time and also presents cytotoxicity problems in its free form, limiting the range of concentrations to be used. In order to overcome these drawbacks and taking advantage of the benefits of nanotechnology, the aim of this work is the development of curcumin loaded polymeric nanoparticles that can provide a controlled release of the drug and enlarge their application in the treatment of inflammatory and oxidative stress related diseases. Specifically, the vehicle is a bioactive terpolymer based on a α-tocopheryl methacrylate, 1-vinyl-2-pyrrolidone and N-vinylcaprolactam. Nanoparticles were obtained by nanoprecipitation and characterized in terms of size, morphology, stability, encapsulation efficiency and drug release. In vitro cellular assays were performed in human articular chondrocyte and RAW 264.7 cultures to assess cytotoxicity, cellular uptake, antioxidant and anti-inflammatory properties. The radical scavenging activity of the systems was confirmed by the DPPH test and the quantification of cellular reactive oxygen species. The anti-inflammatory potential of these systems was demonstrated by the reduction of different pro-inflammatory factors such as IL-8, MCP and MIP in chondrocytes; and nitric oxide, IL-6, TNF-α and MCP-1, among others, in RAW 264.7. Finally, the in vivo biocompatibility was confirmed in a rat model by subcutaneously injecting the nanoparticle dispersions. The reduction of curcumin toxicity and the antioxidant, anti-inflammatory and biocompatibility properties open the door to deeper in vitro and in vivo research on these curcumin loaded polymeric nanoparticles to treat inflammation and oxidative stress based diseases.

Effects of Green Silver Nanoparticles on Apoptosis and Oxidative Stress in Normal and Cancerous Human Hepatic Cells in vitro

Introduction

Extensive use of metallic nanomaterials in different areas of agriculture and commercial products induce significant harmful effects on human health and the environment. In the current study, we synthesized an eco-friendly approach silver nanoparticles (AgNPs) using root extracts of Beta vulgaris L.

Methods

The synthesized green silver nanoparticles (gAgNPs) were characterized by dynamic light scattering (DLS) and high-resolution transmission electron microscope (HR-TEM). The gAgNPs had a round shape and the mean size was 20−50 nm. The cytotoxic effects of gAgNPs were determined in human hepatic normal (CHANG) and cancer (HUH-7) cells by using tetrazolium salt (MTT) and lactate dehydrogenase (LDH) assays for 24 h.

Results and Discussion

It was clear from the observations of this experiment that higher concentrations of gAgNPs reduce cell viability. The production of reactive oxygen species (ROS) was evaluated by using DCFDA. The gAgNPs induced more ROS in the HuH-7 cells than in the CHANG cells. The fragmentation of DNA was evaluated by alkaline single-cell gel electrophoresis and the maximum DNA strand breakage was found at a higher concentration exposure of gAgNPs for 24 h. It is important to notice that the HuH-7 cells showed an increased sensitivity to gAgNPs than the CHANG cells. The apoptotic and necrotic effects of gAgNPs on both the cells were evaluated using annexin-V-FITC and propidium iodide staining. An increased count of apoptotic and necrotic cells was found following a higher concentration exposure of gAgNPs. The apoptotic protein expression in these cells due to gAgNPs exposure was determined using immunoblotting techniques and the level of Bcl2 was decreased. However, the expression of BAX and protein was increased in both cells.

Conclusion

Therefore, it can be concluded that higher concentrations of gAgNPs may induce significant cytotoxicity and cause DNA damage and apoptosis.

Curcumin Delivery Mediated by Bio-Based Nanoparticles: A Review

Todays, nano-pharmaceutics is emerging as an important field of science to develop and improve efficacy of different drugs. Although nutraceuticals are currently being utilized in the prevention and treatment of various chronic diseases such as cancers, a number of them have displayed issues associated with their solubility, bioavailability, and bio-degradability. In the present review, we focus on curcumin, an important and widely used polyphenol, with diverse pharmacological activities such as anti-inflammatory, anti-carcinogenic, anti-viral, etc. Notwithstanding, it also exhibits poor solubility and bioavailability that may compromise its clinical application to a great extent. Therefore, the manipulation and encapsulation of curcumin into a nanocarrier formulation can overcome these major drawbacks and potentially may lead to a far superior therapeutic efficacy. Among different types of nanocarriers, biological and biopolymer carriers have attracted a significant attention due to their pleiotropic features. Thus, in the present review, the potential protective and therapeutic applications of curcumin, as well as different types of bio-nanocarriers, which can be used to deliver curcumin effectively to the different target sites will be discussed.

Methods for Reducing the Toxicity of Metal and Metal Oxide NPs as Biomedicine

The rapid development of medicine has forced equally rapid progress in the field of pharmaceuticals. In connection with the expensive and time-consuming process of finding new drugs, great emphasis is put on the design and use of metal and metal oxides nanoparticles in nanomedicine. The main focus is on comprehensive presentation of both physicochemical properties and the possibilities of using, in particular, silver (Ag) and gold (Au) nanoparticles, as well as zinc oxide (ZnO) and titanium oxide (TiO2) nanoparticles as drug carriers and in the treatment of cancer. An important element of this subject is the possibility of occurrence of toxic effects of these nanoparticles. For this reason, possible mechanisms of toxic actions are presented, as well as methods used to reduce their toxicity to ensure the safety of drug carriers based on these nanostructures.

Contemporary Formulations for Drug Delivery of Anticancer Bioactive Compounds

BACKGROUND

The immense development in the field of anticancer research has led to an increase in the research of bioactive compounds with anticancer potential. It has been known that many bioactive natural compounds have low solubility (and low bioavailability) as their main drawback when it comes to the formulation and drug delivery to specific sites.

OBJECTIVE

As many attempts have been made to overcome this issue, this review gives a summary of the current accomplishments regarding the development of new Drug Delivery Systems (DDSs) represented by nanoparticles (NPs) and exosomes.

METHODS

We analyzed the published data concerning selected compounds that present the most prominent plant secondary metabolites with anticancer potential, specifically flavone (quercetin), isoflavone (genistein and curcumin) and stilbene (resveratrol) groups that have been formulated as NPs and exosomes. In addition, we summarized the patent literature published from 2015-2018 that address these formulations.

RESULTS

Although the exact mechanism of action for the selected natural compounds still remains unclear, the anticancer effect is evident and the main research efforts are directed to finding the most suitable delivery systems. Recent patents in this field serve as evidence that these newly designed natural compound delivery systems could be powerful new anticancer agents in the very near future if the noted difficulties are overcome.

CONCLUSION

The focus of recent research is not only to clarify the exact mechanisms of action and therapeutic effects, but also to answer the issue of suitable delivery systems that can transport sufficient doses of bioactive compounds to the desired target.

Polymers and Polymer Nanocomposites for Cancer Therapy

Synthetic polymers, biopolymers, and their nanocomposites are being studied, and some of them are already used in different medical areas. Among the synthetic ones that can be mentioned are polyolefins, fluorinated polymers, polyesters, silicones, and others. Biopolymers such as polysaccharides (chitosan, hyaluronic acid, starch, cellulose, alginates) and proteins (silk, fibroin) have also become widely used and investigated for applications in medicine. Besides synthetic polymers and biopolymers, their nanocomposites, which are hybrids formed by a macromolecular matrix and a nanofiller (mineral or organic), have attracted great attention in the last decades in medicine and in other fields due to their outstanding properties. This review covers studies done recently using the polymers, biopolymers, nanocomposites, polymer micelles, nanomicelles, polymer hydrogels, nanogels, polymersomes, and liposomes used in medicine as drugs or drug carriers for cancer therapy and underlines their responses to internal and external stimuli able to make them more active and efficient. They are able to replace conventional cancer drug carriers, with better results.

Natural product-based nanoformulations for cancer therapy: Opportunities and challenges

Application of natural product-based nanoformulations for the treatment of different human diseases, such as cancer, is an emerging field. The conventional cancer therapeutic modalities, including surgery, chemotherapy, immunotherapy, radiotherapy has limited achievements. A larger number of drawbacks are associated with these therapies, including damage to proliferating healthy tissues, structural deformities, systemic toxicity, long-term side effects, resistance to the drug by tumor cells, and psychological problems. The advent of nanotechnology in cancer therapeutics is recent; however, it has progressed and transformed the field of cancer treatment at a rapid rate. Nanotherapeutics have promisingly overcome the limitations of conventional drug delivery system, i.e., low aqueous solubility, low bioavailability, multidrug resistance, and non-specificity. Specifically, natural product-based nanoformulations are being intentionally studied in different model systems. Where it is found that these nanoformulations has more proximity and reduced side effects. The nanoparticles can specifically target tumor cells, enhancing the specificity and efficacy of cancer therapeutic modalities which in turn improves patient response and survival. The integration of phytotherapy and nanotechnology in the clinical setting may improve pharmacological response and better clinical outcome of patients.

Gelatin-stabilized composites of silver nanoparticles and curcumin: characterization, antibacterial and antioxidant study

This is a preliminary study of a material comprising gelatin (Gel), silver nanoparticles (AgNPs) and curcumin (Cur) aimed for wound-healing treatment. Gelatin was used to stabilize AgNPs and encapsulate curcumin to form a therapeutic composite (GelCurAg) for their strong bactericidal and antioxidant properties. GelCurAg formulations with different gelatin concentrations were characterized to attain information about their physiochemical properties and the loading efficiency of therapeutic agents. In vitro assessment of GelCurAg focused on antibacterial, antioxidant and cytotoxic aspects. The results suggested that Gel1CurAg (synthesized from 1% gelatin solution) could be utilized as potential therapeutic agents in treating infectious wound owing to its bactericidal and antioxidant effects and low toxicity for clinical uses.

Curcumin in combination with anti-cancer drugs: A nanomedicine review

A huge surge of research is being conducted on combination therapy with anticancer compounds formulated in the form of nanoparticles (NPs). Numerous advantages like dose minimalization and synergism, reversal of multi drug resistance (MDRs), enhanced efficacy have emerged with nanoencapsulation of chemotherapeutic agents with chemo-sensitizing agent like curcumin. Within last couple of years various nano-sized formulations have been designed and tested both in vitro with cell lines for different types of cancers and in vivo with cancer types and drug resistance models. Despite the combinatorial models being advanced, translation to human trials has not been as smooth as one would have hoped, with as few as twenty ongoing clinical trials with curcumin combination, with less than 1/10th being nano-particulate formulations. Mass production of nano-formulation based on their physico-chemical and pharmacokinetics deficits poses as major hurdle up the ladder. Combination of these nano-sized dosage with poorly bioavailable drugs, unspecific target binding ability and naturally unstable curcumin further complicates the formulation aspects. Emphasis is now therefore being laid on altering natural forms of curcumin and usage of formulations like prodrug or coating of curcumin to overcome stability issues and focus more on enhancing the pharmaceutical and therapeutic ability of the nano-composites. Current studies and futuristic outlook in this direction are discussed in the review, which can serve as the basis for upcoming research which could boost commercial translational of improved nano-sized curcumin combination chemotherapy.

Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

During the past few years, silver nanoparticles (AgNPs) became one of the most investigated and explored nanotechnology-derived nanostructures, given the fact that nanosilver-based materials proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications. Among modern biomedical potential of AgNPs, tremendous interest is oriented toward the therapeutically enhanced personalized healthcare practice. AgNPs proved to have genuine features and impressive potential for the development of novel antimicrobial agents, drug-delivery formulations, detection and diagnosis platforms, biomaterial and medical device coatings, tissue restoration and regeneration materials, complex healthcare condition strategies, and performance-enhanced therapeutic alternatives. Given the impressive biomedical-related potential applications of AgNPs, impressive efforts were undertaken on understanding the intricate mechanisms of their biological interactions and possible toxic effects. Within this review, we focused on the latest data regarding the biomedical use of AgNP-based nanostructures, including aspects related to their potential toxicity, unique physiochemical properties, and biofunctional behaviors, discussing herein the intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities of silver-based nanostructures.

Stable PEG-coated silver nanoparticles - A comprehensive toxicological profile

The present study was purported to assess the toxicological profile of bare and polyethylene glycol (PEG) coated spherical silver nanoparticles (AgNPs) by means of in vitro (on human keratinocytes - HaCat cells) and in vivo non-invasive tests (after intraperitoneal - i.p. administration to mice). Bare and PEG-coated AgNPs were synthesized by applying Turkevich's method slightly modified. The physico-chemical characterization revealed the formation of stable, spherical AgNPs and PEG-AgNPs, with narrow size distributions and mean hydrodynamic sizes in the range of 19 nm and 50 nm, respectively. Toxicity data revealed a dose-dependent safe profile for low concentrations of test compounds (<10 μM) in terms of cell viability, whereas higher concentrations were associated with a high rate of cell mortality. In vivo acute/subacute toxicity data showed no denotive changes in mice health status after i.p. administration. Histological observations of internal organs and the biochemical parameters analyzed together with the other biological observations showed a low toxicity level with no major differences related to control, albeit at skin level a reduced number of mast cells was detected. All these observations provide strong support for the idea that coated silver nanoparticles could be applied as targeted nanocarriers for skin pathologies and diagnostic.

Nanoparticle formulations to enhance tumor targeting of poorly soluble polyphenols with potential anticancer properties

Polyphenols have been extensively studied for their relevant anticancer activity. Quite often however their instability, extensive metabolization, low bioavailability and poor solubility limit their application in cancer prevention and therapy. Formulation in nanoparticles has been widely proposed as a means to overcome these limits, maximize localization and specific activity at tumor site. The present review is intended as an update of literature regarding nanoparticulate carriers aimed to deliver polyphenols to the cancer site. Three molecules were chosen, all of which were hydrophobic and poorly soluble, representative of different polyphenol classes: quercetin (QT) among the flavonoid group, curcumin (CUR) as representative of curcuminoids, and resveratrol (RSV) among the stilbenes. In particular, nanoparticulate systems suitable for poorly soluble drugs will be described and attention will be paid to characteristics designed to improve tumor targeting, specific delivery and interaction with tumor cells.