pH-triggered prodrug micelles for cisplatin delivery: Preparation and In Vitro/Vivo evaluation

Stimuli-sensitive polymer prodrug nanocarriers by reversible-deactivation radical polymerization

Polymer prodrugs are based on the covalent linkage of therapeutic molecules to a polymer structure which avoids the problems and limitations commonly encountered with traditional drug-loaded nanocarriers in which drugs are just physically entrapped (e.g., burst release, poor drug loadings). In the past few years, reversible-deactivation radical polymerization (RDRP) techniques have been extensively used to design tailor-made polymer prodrug nanocarriers. This synthesis strategy has received a lot of attention due to the possibility of fine tuning their structural parameters (e.g., polymer nature and macromolecular characteristics, linker nature, physico-chemical properties, functionalization, etc.), to achieve optimized drug delivery and therapeutic efficacy. In particular, adjusting the nature of the drug-polymer linker has enabled the easy synthesis of stimuli-responsive polymer prodrugs for efficient spatiotemporal drug release. In this context, this review article will give an overview of the different stimuli-sensitive polymer prodrug structures designed by RDRP techniques, with a strong focus on the synthesis strategies, the macromolecular architectures and in particular the drug-polymer linker, which governs the drug release kinetics and eventually the therapeutic effect. Their biological evaluations will also be discussed.

Novel aromatic moieties-modified poly(glycidyl amine)s with potent siRNA delivery and cancer treatment effect

The development of safe and effective delivery systems is critical for the clinical applications of siRNA-based therapeutics. Polymer-based vectors have garnered significant attention owing to their structural flexibility and functional tunability. Polyethyleneimine (PEI) has been extensively studied for nucleic acid delivery; nevertheless, its high cytotoxicity has posed challenges for clinical applications. In this study, we have reported poly(glycidyl amine) (PGAm), a linear PEI analogue, demonstrating remarkable siRNA delivery efficacy and improved biocompatibility. By introducing three aromatic moieties (tyrosine, p-hydroxybenzenepropanoic acid, and phenylalanine) at varying ratios to further modify PGAms, we successfully constructed a library comprising 36 PGAm-based carriers. In vitro evaluations revealed that PGAm-based carriers exhibited significantly enhanced biocompatibility and reduced non-specific protein absorption in comparison to PEI25k. Among them, 10 modified PGAms achieved a knockdown of target gene expressions exceeding 80%, and 26 modified PGAms maintained over 70% cell viability when utilized for the in vitro delivery of siRNA to HeLa cells. Explorations into the structure-activity relationship of PGAm-based polyplex nanoparticles (NPs) indicated that the siRNA delivery efficacy of NPs depended on factors such as the molecular weight of PGAm precursors, the type of modifying moieties, and the modification ratio. Furthermore, it was demonstrated that two top-performing NPs, namely 2T100/siLuc and 2A50/siLuc, exhibited potent silencing of target genes in tumors following i.v. injection into mice bearing HeLa-Luc xenografts. The in vivo efficacy of the selected NPs was further validated by a remarkable anti-cancer effect when employed for the delivery of siRNA targeting polo-like kinase 1 (siPLK1) to mice with PC-3 xenograft tumors. The intravenous administration of NPs resulted in a substantial inhibition of tumor growth without significant toxicity. These findings demonstrate the feasibility of employing PGAm in siRNA delivery and provide valuable insights for the development of efficient siRNA carriers based on PGAm.

Targeted co-delivery of methotrexate and chloroquine via a pH/enzyme-responsive biocompatible polymeric nanohydrogel for colorectal cancer treatment

Application of conventional chemotherapy regardless of its unique effectiveness have been gradually being edged aside due to limited targeting capability, lack of selectivity and chemotherapy-associated side effects. To this end, colon-targeted nanoparticles via combination therapy have shown great therapeutic potential against cancer. Herein, pH/enzyme-responsive biocompatible polymeric nanohydrogels based on poly(methacrylic acid) (PMAA) containing methotrexate (MTX) and chloroquine (CQ) were fabricated. PMAA-MTX-CQ exhibited high drug loading capacity of which MTX was 4.99% and was CQ 25.01% and displayed pH/enzyme-triggered drug release behavior. Higher CQ release rate (76%) under simulated acidic microenvironment of tumor tissue whereas 39% of CQ was released under normal physiological conditions. Intestinally, MTX release was facilitated in the presence of proteinase K enzyme. TEM image demonstrated spherical morphology with particle size of less than 50 nm. In vitro and in vivo toxicity assessments indicated that developed nanoplatforms possessed great biocompatibility. These nanohydrogels did not cause any adverse effects against Artemia Salina and HFF2 cells (around 100% cell viability) which highlight the safety of prepared nanohydrogels. There was no death in mice received different concentrations of nanohydrogel through oral administration and less than 5% hemolysis was found in red blood cells incubated with PMAA nanohydrogels. In vitro anti-cancer results showed that combination therapy based on PMAA-MTX-CQ can effectively suppress the growth of SW480 colon cancer cells (29% cell viability) compared to monotherapy. Altogether, these findings suggest that pH/enzyme-responsive PMAA-MTX-CQ could effectively inhibit cancer cell growth and progression via site-specific delivery of its cargo in a safe and controlled manner.

Self-assembled magnetic polymeric micelles for delivery of quercetin: Toxicity evaluation on isolated rat liver mitochondria

Multifunctional nanocarriers as a promising platform could provide numerous opportunities in the field of drug delivery. Drug carriers loaded with both magnetic nanoparticles (MNPs) and therapeutic agents would allow the combination of chemotherapy with the possibility of monitoring or controlling the distribution of the nano vehicles in the body which may improve the effectiveness of the therapy. Furthermore, by applying these strategies, triggering drug release and/or synergistic hyperthermia treatment are also reachable. This study aimed to explore the potential of the quercetin (QUR) loaded magnetic nano-micelles for improving drug bioavailability while reducing the drug adverse effects. The bio-safety of developed QUR loaded magnetic nano-micelles (QMNMs) were conducted via mitochondrial toxicity using isolated rat liver mitochondria including glutathione (GSH), malondialdehyde (MDA), and the ferric reducing ability of plasma (FRAP). QMNMs with a mean particle size of 85 nm (PDI value of 0.269) and great physical stability were produced. Also, TEM images indicated that the prepared QMNMs were semi-spherical in shape. These findings also showed that the constructed QMNMs, as a pH-sensitive drug delivery system, exhibited a stable and high rate of QUR release under mildly acidic conditions pH (5.3) compared to neutral pH (7.4). The most striking result to emerge from the data is that an investigation of various mitochondrial functional parameters revealed that both QMNMs and QUR have no specific mitochondrial toxicity. Altogether, these results offer overwhelming evidence for the bio-safety of QMNMs and might be used as an effective drug delivery system for targeting and stimuli-responsive QUR delivery.

Recent advances in targeting malaria with nanotechnology-based drug carriers

Malaria, as one of the most common human infectious diseases, remains the greatest global health concern, since approximately 3.5 billion people around the world, especially those in subtropical areas, are at the risk of being infected by malaria. Due to the emergence and spread of drug resistance to the current antimalarials, malaria-related mortality and incidence rates have recently increased. To overcome the aforementioned obstacles, nano-vehicles based on biodegradable, natural, and non-toxic polymers have been developed. Accordingly, these systems are considered as a potential drug vehicle, which due to their unique properties such as the excellent safety profile, good biocompatibility, tunable structure, diversity, and the presence of functional groups within the polymer structure, could facilitate covalent attachment of targeting moieties and antimalarials to the polymeric nano-vehicles. In this review, we highlighted some recent developments of liposomes as unique nanoscale drug delivery vehicles and several polymeric nanovehicles, including hydrogels, dendrimers, self-assembled micelles, and polymer-drug conjugates for the effective delivery of antimalarials.

Nanotechnology against the novel coronavirus (severe acute respiratory syndrome coronavirus 2): diagnosis, treatment, therapy and future perspectives

COVID-19, as an emerging infectious disease, has caused significant mortality and morbidity along with socioeconomic impact. No effective treatment or vaccine has been approved yet for this pandemic disease. Cutting-edge tools, especially nanotechnology, should be strongly considered to tackle this virus. This review aims to propose several strategies to design and fabricate effective diagnostic and therapeutic agents against COVID-19 by the aid of nanotechnology. Polymeric, inorganic self-assembling materials and peptide-based nanoparticles are promising tools for battling COVID-19 as well as its rapid diagnosis. This review summarizes all of the exciting advances nanomaterials are making toward COVID-19 prevention, diagnosis and therapy.

pH-sensitive curcumin conjugated micelles for tumor triggered drug delivery

Development of new drugs are confronted with some barriers and challenges, since these projects are mainly expensive, complex, time consuming with lack of success, there is an urgent need to reformulate the current poorly water soluble anti-cancer drugs. In this study, a new type of polymer-curcumin conjugates based on glycidyl azide polymer (GAP) was developed for cancer therapy. The copolymer was used for delivery of curcumin (CUR) as an anticancer drug to cancer cells. Our method is based on the facile conjugation of CUR to amine-containing polymeric vehicles through imine linkage bonds, which could remain stable in normal physiological condition while readily dissociate by an acidic environment and make the prodrug active to liberate its payload CUR to inhibit cell growth. The results demonstrated that fabricated amphiphilic PDCs were self-assembled into nanosized micelles in aqueous solution and the micelles showed an average size of 180 nm with a good polydispersity index. Drug release studies demonstrated that this nano-conjugate is fairly stable at physiologic environments but prone to mild acidic conditions which would trigger the release of conjugated CUR. Moreover, the PDCs micelles exhibited excellent cytotoxicity effect on 4T1 mouse breast cancer cell line but no significant toxicity was observed for the copolymer. In addition, the copolymer did not display remarkable toxicity against A. salina even at high doses of copolymer. In addition, the synthesized PDCs exhibited hemolysis lowers than 6%. The safety of copolymers as a drug vehicle was also confirmed by LD₅₀, since all mice which treated with 5000 mg/Kg (limited dose) were still alive after one week. Our findings revealed that these unique pH-sensitive PDCs may provide a promising approach for delivery of the anticancer drugs to cancer cells.[Formula: see text].

Polymer-hybrid nanoparticles: Current advances in biomedical applications

The unique properties of polymer-hybrid nanosystems enable them to play an important role in different fields such as biomedical applications. Hybrid materials, which are formed by polymer and inorganic- or organic-base systems, have been the focus of many recently published studies whose results have shown outstanding improvements in drug targeting. The development of hybrid polymer materials can avoid the synthesis of new molecules, which is an overall expensive process that can take several years to get to the proper elaboration and approval. Thus, the combination of properties in a single hybrid system can have several advantages over non-hybrid platforms, such as improvements in circulation time, structural disintegration, high stability, premature release, low encapsulation rate and unspecific release kinetics. Thus, the aim of the present review is to outline a rapid and well-oriented scenario concerning the knowledge about polymer-hybrid nanoparticles use in biomedical platforms. Furthermore, the ultimate methodologies adopted in synthesis processes, as well as in applications in vitro/in vivo, are the focus of this review.

Fabrication of oxidized bacterial cellulose by nitrogen dioxide in chloroform/cyclohexane as a highly loaded drug carrier for sustained release of cisplatin

Carboxylated bacterial cellulose (OBC) was fabricated by oxidation with nitrogen dioxide in chloroform/cyclohexane and employed as a carrier for sustained release of antitumor substance cisplatin (CDDP). The influence of removing water method, solvent used in the synthesis, concentration of N₂O₄, and duration of the oxidation on content of carboxyl groups in reaction products was established. Due to the possibility of nitrogen dioxide to penetrate into cellulose crystallites, the carboxyl group content of the OBC reaches high values up to 4 mmol/g. In vitro degradation of OBC was determined under simulated physiological conditions. The immobilization of CDDP on OBC was studied in detail. The initial burst release of the drug from the polymer was depressed. The cytotoxicity of CDDP-loaded OBC was evaluated with HeLa cells. The unique structure and properties of OBC make it a great candidate as drug delivery carrier.