Influence of indomethacin-loading on the micellization and drug release of thermosensitive dextran-graft-poly(N-isopropylacrylamide)

Self-healing hydrogel from poly(aspartic acid) and dextran with antibacterial property for burn wound healing

Designing hydrogel dressing with intrinsic antibacterial property to promote skin injury recovery remains a significant challenge. In this research, poly(aspartic hydrazide) with grafted betaine (PAHB) was designed and reacted with oxidized dextran (OD) to fabricate biodegradable PAHB/OD hydrogel and its application as wound dressing was systematically investigated. The PAHB/OD hydrogels exhibited fast gelation, strong tissue adhesion, preferable mechanical properties and biocompatibility. The grafted betaine endowed the hydrogel with antibacterial property and antibacterial rate enhanced through photothermal performance of composited CuS nanoparticles under near infrared (NIR) radiation. The CuS composited PAHB/OD hydrogel (CuS/hydrogel) with microporous morphology was used as burn wound dressing with loaded anti-inflammatory drug diclofenac sodium (DS) in mouse model. The results showed the DS loaded CuS/hydrogel (CuS@DS/hydrogel) promoted the tissue regeneration and suppressed the inflammatory response. The histological analysis and immunohistochemical expression confirmed the CuS@DS/hydrogel promote angiogenesis of the burn wound by regulating the expression of inflammatory cytokines (IL-6 and CD68) and vascular endothelial growth factor (VEGF). Overall, the CuS@DS/hydrogel hydrogel is a promising candidate as wound dressing due to its tissue adhesive, antioxidant, antibacterial and anti-inflammatory activities.

Doxorubicin-galactomannan nanoconjugates for potential cancer treatment

In this study, we report the synthesis and characterization of pH-responsive nanoconjugates for targeted drug delivery. Galactomannan extracted from D. regia seeds was oxidized to form aldehyde groups, achieving a percentage of oxidation of 25.6 %. The resulting oxidized galactomannan (GMOX) was then copolymerized with PINIPAm-NH2, yielding a copolymer. The copolymer exhibited signals from both GMOX and PNIPAm-NH2 in its NMR spectrum, confirming successful copolymerization. Critical association concentration (CAC) studies revealed the formation of nanostructures, with lower CAC values observed at higher temperatures. The copolymer and GMOX reacted with doxorubicin (DOX), resulting in nanoconjugates with controlled drug release profiles, especially under acidic conditions similar to tumor microenvironments. Cytotoxicity assays demonstrated significant efficacy of the nanoconjugates against melanoma cells with reduced toxicity towards healthy cells. These findings underscore the potential of the pH-responsive nanoconjugates as promising candidates for targeted cancer therapy, offering improved therapeutic efficacy and reduced systemic side effects.

Paclitaxel-loaded ROS-responsive nanoparticles for head and neck cancer therapy

High intracellular reactive oxygen species (ROS) level is characteristic of cancer cells and could act as a target for the efficient targeted drug delivery for cancer treatment. Consequently, biomaterials that react to excessive levels of ROS are essential for biomedical applications. In this study, a novel ROS-responsive polymer based on D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) and poly (β-thioester) (TPGS-PBTE) was synthesized for targeted delivery of the first-line antineoplastic drug, paclitaxel (PTX). The resultant TPGS-PBTE NPs showed good ROS-responsive capability in size change and drug release. Compared to PTX, PTX-loaded nanoparticles (PTX@TPGS-PBTE NPs) showed enhanced cytotoxicity and higher level of apoptosis toward squamous cell carcinoma (SCC-7) cells. Tumor-targeted delivery of the NPs was also observed, especially after being modified with a tumor-targeting peptide, cRGD. Enhanced tumor growth inhibition was also observed in head and neck cancer SCC-7 murine models. In summary, PTX@TPGS-PBTE NPs can achieve good therapeutic effects of PTX against head and neck cancer both in vitro and in vivo, especially when modified by cRGD for active targeting, which enriched the application of ROS responsive system utilized in the delivery of anticancer drugs.

Amphiphilic Block Copolymers: Their Structures, and Self-Assembly to Polymeric Micelles and Polymersomes as Drug Delivery Vehicles

Self-assembly of amphiphilic block copolymers display a multiplicity of nanoscale periodic patterns proposed as a dominant tool for the 'bottom-up' fabrication of nanomaterials with different levels of ordering. The present review article focuses on the recent updates to the self-association of amphiphilic block copolymers in aqueous media into varied core-shell morphologies. We briefly describe the block copolymers, their types, microdomain formation in bulk and micellization in selective solvents. We also discuss the characteristic features of block copolymers nanoaggregates viz., polymer micelles (PMs) and polymersomes. Amphiphilic block copolymers (with a variety of hydrophobic blocks and hydrophilic blocks; often polyethylene oxide) self-assemble in water to micelles/niosomes similar to conventional nonionic surfactants with high drug loading capacity. Double hydrophilic block copolymers (DHBCs) made of neutral block-neutral block or neutral block-charged block can transform one block to become hydrophobic under the influence of a stimulus (physical/chemical/biological), and thus induced amphiphilicity and display self-assembly are discussed. Different kinds of polymer micelles (viz. shell and core-cross-linked, core-shell-corona, schizophrenic, crew cut, Janus) are presented in detail. Updates on polymerization-induced self-assembly (PISA) and crystallization-driven self-assembly (CDSA) are also provided. Polyion complexes (PICs) and polyion complex micelles (PICMs) are discussed. Applications of these block copolymeric micelles and polymersomes as nanocarriers in drug delivery systems are described.

Dual responsive dextran-graft-poly (N-isopropylacrylamide)/doxorubicin prodrug via Schiff base reaction

Stimulus-responsive nanoparticles stand out in studies for cancer treatment since these systems can promote a selective release of the drug in tumor tissues and cells, minimizing the effects caused by conventional chemotherapy. Dextran-graft-poly (N-isopropylacrylamide) copolymers were synthesized via Schiff base formation. The synthesis of copolymers was confirmed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (NMR) and the analyses of dynamic light scattering (DLS) showed that the copolymers were thermal and pH dual-responsive. The chemotherapy drug doxorubicin (DOX) was conjugated to the copolymers via Schiff base formation, obtaining nanoparticles by self-assembling with size smaller than 130 nm. A higher percentage of doxorubicin was released at pH 5.0 (59.1 ± 2.1%) compared to physiological pH (34.9 ± 4.8%), confirming a pH-sensitive release profile. The in vitro cytotoxicity assay demonstrated that DOX-loaded nanoparticles can inhibit cancer cell proliferation and promote reduced cytotoxicity in non-tumor cells. The D_45kP_30k-DOX nanoparticles induced morphological changes in HCT-116 cells suggesting cell death and the cell uptake assay indicated that the nanoparticles can be internalized by endocytosis. Therefore, DOX-loaded nanoparticles exhibited potential as smart systems for cancer treatment.

Doxorubicin and adjudin co-loaded pH-sensitive nanoparticles for the treatment of drug-resistant cancer

Multi-drug resistance (MDR) of tumor is a major cause of chemotherapy failure. In this study, a pH-sensitive graft copolymer, poly(β-amino ester)-g-β-cyclodextrin (PBAE-g-β-CD), was synthesized via Michael addition polymerization and was employed to co-deliver doxorubicin (DOX), a chemotherapy agent, and adjudin (ADD), a mitochondrial inhibitor, in the form of dual-drug co-loaded nanoparticles (NPs). Specifically, DOX was conjugated to 1-adamantaneacetic acid (Aa) to generate a prodrug that was subsequently encapsulated in the cavity of cyclodextrin via host-guest interactions. In addition, ADD was encapsulated by poly(β-aminoester) (PBAE). The introduction of the Aa-d-α-tocopheryl polyethylene glycolsuccinate (TPGS) conjugate enhanced the biocompatibility and serum stability of the resulting NPs. The NPs can realize precise ratiometric control of drugs being loaded, increase cellular uptake of the drugs, induce mitochondrial dysfunction and augment tumor treatment efficiency by inducing apoptosis. Western blot and polymerase chain reaction analyses showed that inhibition of P-glycoprotein and X-linked inhibitor of apoptosis protein expression may underlie inhibition of tumor resistance mediated by NPs. The MCF-7/ADR xenograft tumor model also revealed that in comparison with DOX, the NPs exhibited satisfactory performance in promoting apoptosis of tumor cells and achieved high therapeutic outcomes for MDR tumors. STATEMENT OF SIGNIFICANCE: Combination chemotherapy is an effective way to overcome MDR of tumor. However, one of the major obstacles for successful combination chemotherapy is the co-loading, co-delivery and controlled release of two different drugs, whose chemo-physical properties may be totally different. In this study, a pH-sensitive NP system was designed to realize the co-loading and precise ratiometric control of DOX and ADD, as well as the programmed drug release. That is, ADD release was triggered by low pH in endo/lysosome after endocytosis and then DOX was hydrolyzed to achieve a sustained release in tumor cells. Therefore, the NPs exhibited an effectively growth inhibition against MDR cells both in vitro and in vivo via the synergistic effect of ADD and DOX, which provided a promising strategy for treatment of MDR cancer.

Dually sensitive dextran-based micelles for methotrexate delivery

Temperature and pH-sensitive micelles prepared from dextran grafted with poly(N-isopropylacrylamide) (PNIPAAm)/polyethylene glycol methyl ether (PEGMA) with/without 2-aminoethylmethacrylate (2-AEM) were evaluated as methotrexate delivery systems.

Facile construction of near-monodisperse and dual responsive polycarbonate mixed micelles with the ability of pH-induced charge reversal for intracellular delivery of antitumor drugs

A mixed strategy was used to construct size-adjustable, pH and redox dual-responsive, near-monodisperse and charge-conversional core-shell polycarbonate carriers. First, two kinds of random polycarbonates (PC(Arss-N2CH₃)) with different ratios of hydrophobic disulfide (Arss) and hydrophilic dimethylamine functional groups (N2CH₃) (relatively hydrophobic polycarbonate (BPC) with more disulfide groups and relatively hydrophilic polycarbonate (LPC) with more dimethylamine groups) were used to construct near-monodisperse core micelles in pH 7.4 PBS. Then, a negatively charged shell polymer, poly(ethylene glycol)-b-1,2-dicarboxylic-cyclohexene anhydride modified amino polycarbonate (PEG-PCDCA), bearing acid-labile β-carboxylic amides, was added to the core micelle solution to get the desired mixed micelle. The assembly process, pH induced charge-reversal, and dual-response abilities of the resultant mixed micelles were thoroughly studied using zeta potential and dynamic light scattering (DLS). Two model drugs, Nile red (NR) and doxorubicin (DOX), were successfully loaded into the micelle and could be released in response to dithiothreitol (DTT) and acidic conditions. Confocal microscopy indicated that the micelle system could achieve effective cellular uptake and DOX release in Hela cells. Moreover, the blank micelle and the drug-loaded mixed micelle showed slight and great cytotoxicity against Hela cells, respectively, indicating their significant potential in cancer therapy.

Temperature-Induced Assembly of Monodisperse, Covalently Cross-Linked, and Degradable Poly(N-isopropylacrylamide) Microgels Based on Oligomeric Precursors

A simple, rapid, solvent-free, and scalable thermally driven self-assembly approach is described to produce monodisperse, covalently cross-linked, and degradable poly(N-isopropylacrylamide) (PNIPAM) microgels based on mixing hydrazide (PNIPAM-Hzd) and aldehyde (PNIPAM-Ald) functionalized PNIPAM precursors. Preheating of a seed PNIPAM-Hzd solution above its phase transition temperature produces nanoaggregates that are subsequently stabilized and cross-linked by the addition of PNIPAM-Ald. The ratio of PNIPAM-Hzd:PNIPAM-Ald used to prepare the microgels, the time between PNIPAM-Ald addition and cooling, the temperature to which the PNIPAM-Hzd polymer solution is preheated, and the concentration of PNIPAM-Hzd in the initial seed solution can all be used to control the size of the resulting microgels. The microgels exhibit similar thermal phase transition behavior to conventional precipitation-based microgels but are fully degradable into oligomeric precursor polymers. The microgels can also be lyophilized and redispersed without any change in colloidal stability or particle size and exhibit no significant cytotoxicity in vitro. We anticipate that microgels fabricated using this approach may facilitate translation of the attractive properties of such microgels in vivo without the concerns regarding microgel clearance that exist with other PNIPAM-based microgels.

A review on comb-shaped amphiphilic polymers for hydrophobic drug solubilization

Comb-shaped amphiphilic polymers are rapidly emerging as an alternative approach to amphiphilic block copolymers for hydrophobic drug solubilization. These polymers consist of a homopolymer or copolymer backbone to which hydrophobic and hydrophilic pendant groups can be grafted resulting in a comb-like architecture. The hydrophobic pendants may consist of homopolymers, copolymers and other low-molecular weight hydrophobic structures. In this review, we focus on hydrophobically modified preformed homopolymers. Comb-shaped amphiphilic polymers possess reduced critical aggregation concentration values compared with traditional surfactant micelles indicating increased stability with decreased disruption experienced on dilution. They have been fabricated with diverse architectures and multifunctional properties such as site-specific targeting and external stimuli-responsive nature. The application of comb-shaped amphiphilic polymers is expanding; here we report on the progress achieved so far in hydrophobic drug solubilization for both intravenous and oral delivery.