A copper-loaded self-assembled nanoparticle for disturbing the tumor redox balance and triple anti-tumor therapy

Both chemodynamic therapy and photodynamic therapy, based on the production of reactive oxygen (ROS), have excellent potential in cancer therapy. However, the abnormal redox homeostasis in tumor cells, especially the overexpressed glutathione (GSH) could scavenge ROS and reduce the anti-tumor efficiency. Therefore, it is essential to develop a simple and effective tumor-specific drug delivery system for modulating the tumor microenvironment (TME) and achieving synergistic therapy at the tumor site. In this study, self-assembled nanoparticles (named CDZP NPs) were developed using copper ion (Cu2+), doxorubicin (Dox), zinc phthalocyanine (ZnPc) and a trace amount of poly(2-(di-methylamino)ethylmethacrylate)-poly[(R)-3-hydroxybutyrate]-poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA-PHB-PDMAEMA) through chelation, π-π stacking and hydrophobic interaction. These triple factor-responsive (pH, laser and GSH) nanoparticles demonstrated unique advantages through the synergistic effect. Highly controllable drug release ensured its effectiveness at the tumor site, Dox-induced chemotherapy and ZnPc-mediated fluorescence (FL) imaging exhibited the distribution of nanoparticles. Meanwhile, Cu2+-mediated GSH-consumption not only reduced the intracellular ROS elimination but also produced Cu+ to catalyze hydrogen peroxide (H2O2) and generated hydroxyl radicals (˙OH), thereby enhancing the chemodynamic and photodynamic therapy. Herein, this study provides a green and relatively simple method for preparing multifunctional nanoparticles that can effectively modulate the TME and improve synergetic cancer therapy.

Synthesis and physical properties of polyhydroxyalkanoate (PHA)-based block copolymers: A review

Polyhydroxyalkanoates (PHAs) are a group of natural polyesters that are synthesised by microorganisms. In general, their thermoplasticity and (in some forms) their elasticity makes them attractive alternatives to petrochemical-derived polymers. However, the high crystallinity of some PHAs - such as poly(3-hydroxybutyrate) (P3HB) - results in brittleness and a narrow processing window for applications such as packaging. The production of copolymeric PHA materials is one approach to improving the mechanical and thermal properties of PHAs. Another solution is the manufacture of PHA-based block copolymers. The incorporation of different polymer and copolymer blocks coupled to PHA, and the resulting tailorable microstructure of these block copolymers, can result in a step-change improvement in PHA-based material properties. A range of production strategies for PHA-based block copolymers has been reported in the literature, including biological production and chemical synthesis. Biological production is typically less controllable, with products of a broad molecular weight and compositional distribution, unless finely controlled using genetically modified organisms. By contrast, chemical synthesis delivers relatively controllable block structures and narrowly defined compositions. This paper reviews current knowledge in the areas of the production and properties of PHA-based block copolymers, and highlights knowledge gaps and future potential areas of research.

A novel block copolymer containing gadolinium oxide nanoparticles in ultrasound assisted-dispersive solid phase microextraction of total arsenic in human foodstuffs: A multivariate optimization methodology

A new poly(3-hydroxy butyrate)-b-poly(dimethyl amino ethyl methacrylate) amphiphilic block copolymer containing gadolinium oxide nanoparticles (PHB-PDMAEMA-Gd2O3-NPs) were synthesized and used as composite adsorbent for extraction of total arsenic. Characterization of the composite adsorbent material PHB-PDMAEMA-Gd2O3-NP was studied using spectroscopic techniques. Plackett-Burman design and central composite design were employed to screening and optimization of the experimental parameters. This composite adsorbent was utilized in ultrasound assisted-dispersive solid phase microextraction (UA-dSPµE) for the determination of total inorganic arsenic in foodstuffs through hydride generation atomic absorption spectrometry (HG-AAS). It demonstrates a linear relationship across arsenic concentration range of 0.07-1.12 µg/L with a correlation coefficient (0.996). It's showed an enrichment factor of 128 and a limit of detection 0.02 µg/L for total inorganic arsenic determination. Accuracy of the developed method was confirmed through the analysis of certified reference materials with 96.0-98.5% recovery. It proved to be significantly useful UA-dSPµE method for determining total inorganic arsenic in different foodstuffs.

A bio-functional polymer that prevents retinal scarring through modulation of NRF2 signalling pathway

One common cause of vision loss after retinal detachment surgery is the formation of proliferative and contractile fibrocellular membranes. This aberrant wound healing process is mediated by epithelial-mesenchymal transition (EMT) and hyper-proliferation of retinal pigment epithelial (RPE) cells. Current treatment relies primarily on surgical removal of these membranes. Here, we demonstrate that a bio-functional polymer by itself is able to prevent retinal scarring in an experimental rabbit model of proliferative vitreoretinopathy. This is mediated primarily via clathrin-dependent internalisation of polymeric micelles, downstream suppression of canonical EMT transcription factors, reduction of RPE cell hyper-proliferation and migration. Nuclear factor erythroid 2-related factor 2 signalling pathway was identified in a genome-wide transcriptomic profiling as a key sensor and effector. This study highlights the potential of using synthetic bio-functional polymer to modulate RPE cellular behaviour and offers a potential therapy for retinal scarring prevention.

Supramolecular Hydrogels: Design Strategies and Contemporary Biomedical Applications

Self-assembly of supramolecular hydrogels is driven by dynamic, non-covalent interactions between molecules. Considerable research effort has been exerted to fabricate and optimise supramolecular hydrogels that display shear-thinning, self-healing, and reversibility, in order to develop materials for biomedical applications. This review provides a detailed overview of the chemistry behind the dynamic physicochemical interactions that sustain hydrogel formation (hydrogen bonding, hydrophobic interactions, ionic interactions, metal-ligand coordination, and host-guest interactions). Novel design strategies and methodologies to create supramolecular hydrogels are highlighted, which offer promise for a wide range of applications, specifically drug delivery, wound healing, tissue engineering and 3D bioprinting. To conclude, future prospects are briefly discussed, and consideration given to the steps required to ultimately bring these biomaterials into clinical settings.

High molecular weight hyper-branched PCL-based thermogelling vitreous endotamponades

Vitreous endotamponades play essential roles in facilitating retina recovery following vitreoretinal surgery, yet existing clinically standards are suboptimal as they can cause elevated intra-ocular pressure, temporary loss of vision, and cataracts while also requiring prolonged face-down positioning and removal surgery. These drawbacks have spurred the development of next-generation vitreous endotamponades, of which supramolecular hydrogels capable of in-situ gelation have emerged as top contenders. Herein, we demonstrate thermogels formed from hyper-branched amphiphilic copolymers as effective transparent and biodegradable vitreous endotamponades for the first time. These hyper-branched copolymers are synthesised via polyaddition of polyethylene glycol, polypropylene glycol, poly(ε-caprolactone)-diol, and glycerol (branch inducing moiety) with hexamethylene diisocyanate. The hyper-branched thermogels are injected as sols and undergo spontaneous gelation when warmed to physiological temperatures in rabbit eyes. We found that polymers with an optimal degree of hyper-branching showed excellent biocompatibility and was able to maintain retinal function with minimal atrophy and inflammation, even at absolute molecular weights high enough to cause undesirable in-vivo effects for their linear counterparts. The hyper-branched thermogel is cleared naturally from the vitreous through surface hydrogel erosion and negates surgical removal. Our findings expand the scope of polymer architectures suitable for in-vivo intraocular therapeutic applications beyond linear constructs.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. Coli ATCC 25922 and MCR 1+ E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

Biomaterials by design: Harnessing data for future development

Biomaterials is an interdisciplinary field of research to achieve desired biological responses from new materials, regardless of material type. There have been many exciting innovations in this discipline, but commercialization suffers from a lengthy discovery to product pipeline, with many failures along the way. Success can be greatly accelerated by harnessing machine learning techniques to comb through large amounts of data. There are many potential benefits of moving from an unstructured empirical approach to a development strategy that is entrenched in data. Here, we discuss the recent work on the use of machine learning in the discovery and design of biomaterials, including new polymeric, metallic, ceramics, and nanomaterials, and how machine learning can interface with emerging use cases of 3D printing. We discuss the steps for closer integration of machine learning to make this exciting possibility a reality.

Novel Amphiphilic Block Copolymers for the Formation of Stimuli-Responsive Non-Lamellar Lipid Nanoparticles

Non-lamellar lyotropic liquid crystalline (LLC) lipid nanoparticles contain internal multidimensional nanostructures such as the inverse bicontinuous cubic and the inverse hexagonal mesophases, which can respond to external stimuli and have the potential of controlling drug release. To date, the internal LLC mesophase responsiveness of these lipid nanoparticles is largely achieved by adding ionizable small molecules to the parent lipid such as monoolein (MO), the mixture of which is then dispersed into nanoparticle suspensions by commercially available poly(ethylene oxide)-poly(propylene oxide) block copolymers. In this study, the Reversible Addition-Fragmentation chain Transfer (RAFT) technique was used to synthesize a series of novel amphiphilic block copolymers (ABCs) containing a hydrophilic poly(ethylene glycol) (PEG) block, a hydrophobic block and one or two responsive blocks, i.e., poly(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl acrylate) (PTBA) and/or poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). High throughput small angle X-ray scattering studies demonstrated that the synthesized ABCs could simultaneously stabilize a range of LLC MO nanoparticles (vesicles, cubosomes, hexosomes, inverse micelles) and provide internal particle nanostructure responsiveness to changes of hydrogen peroxide (H2O2) concentrations, pH and temperature. It was found that the novel functional ABCs can substitute for the commercial polymer stabilizer and the ionizable additive in the formation of next generation non-lamellar lipid nanoparticles. These novel formulations have the potential to control drug release in the tumor microenvironment with endogenous H2O2 and acidic pH conditions.

Biomedical Applications of Bacteria-Derived Polymers

Plastics have found widespread use in the fields of cosmetic, engineering, and medical sciences due to their wide-ranging mechanical and physical properties, as well as suitability in biomedical applications. However, in the light of the environmental cost of further upscaling current methods of synthesizing many plastics, work has recently focused on the manufacture of these polymers using biological methods (often bacterial fermentation), which brings with them the advantages of both low temperature synthesis and a reduced reliance on potentially toxic and non-eco-friendly compounds. This can be seen as a boon in the biomaterials industry, where there is a need for highly bespoke, biocompatible, processable polymers with unique biological properties, for the regeneration and replacement of a large number of tissue types, following disease. However, barriers still remain to the mass-production of some of these polymers, necessitating new research. This review attempts a critical analysis of the contemporary literature concerning the use of a number of bacteria-derived polymers in the context of biomedical applications, including the biosynthetic pathways and organisms involved, as well as the challenges surrounding their mass production. This review will also consider the unique properties of these bacteria-derived polymers, contributing to bioactivity, including antibacterial properties, oxygen permittivity, and properties pertaining to cell adhesion, proliferation, and differentiation. Finally, the review will select notable examples in literature to indicate future directions, should the aforementioned barriers be addressed, as well as improvements to current bacterial fermentation methods that could help to address these barriers.

A pH-Sensitive Self-Assembled and Carrier-Free Nanoparticle Based on Charge Reversal for Enhanced Synergetic Chemo-Phototherapy

To overcome biological barriers for nanoparticles (NPs) efficaciously accumulated at tumor sites, as well as enhancing the performance of drug delivery systems, a carrier-free nanoparticle based on charge reversal is designed for improved synergetic chemo-phototherapy for cancer treatment. In this system, doxorubicin (Dox) and zinc phthalocyanine (ZnPc) are self-assembled through noncovalent interactions (π-π stacking, hydrophobic forces) to avoid the possible toxicity of excipient, complex chemical conjugations and batch-to-batch variation. A trace amount of poly(2-(di-methylamino) ethylmethacrylate)- poly[(R)-3-hydroxybutyrate]- poly(2-(dimethylamino) ethylmethacrylate (PDMAEMA-PHB-PDMAEMA) is modified on the surface of Dox-ZnPc to construct the novel nanoparticles, namely DZP, with long-term stability, and with a dual-drug load content of up to ≈90％. The drug delivery system (DDS) can effectively decrease its toxicity among physical circulation and increase the accumulation at the tumor site. Moreover, the developed DZP nanoparticles show excellent photo-chemotherapy, photoacoustic (PA) and fluorescence (FL) imaging characteristics for multimodal imaging-guided synergetic therapy.

Cationic Poly([R]-3-hydroxybutyrate) Copolymers as Antimicrobial Agents

Poly([R]-3-hydroxybutyrate) (PHB), a natural biodegradable polyester, has attracted much attention as a new biomaterial because of its sustainability and good biocompatibility. In this study, it is discovered that PHB can be conveniently functionalized to obtain a number of platform chain architectures that may provide a wide range of functional copolymers. In a transesterification reaction, linear (di-hydroxylated) and star shaped (tri- and tetra-hydroxylated) PHB oligomers are synthesized, followed by copolymerization with 2-(dimethylamino)ethyl methacrylate and quaternization with benzyl bromide to afford antimicrobial properties. The antimicrobial activities of the quaternary salts against clinically relevant pathogens on the interactions with outer and cytoplasmic membranes, lethal mechanisms, multipassage resistance, and synergy effect with antibiotics are investigated. Cationic PHB copolymers show effectiveness as antimicrobial agents, with minimum inhibitory concentration values 0.24-0.65 µm (or µmol dm^-3 ) (or 32-128 µg mL^-1 ) against Gram-positive and Gram-negative bacteria. Modifying the copolymer architectures into star shapes results in enhanced effectiveness to disrupt the membrane integrity. Synergistic effects are attained for all the quaternized PHB derivatives when they are used together with tobramycin. Multipassage resistance does not occur in both the linear and star derivatives against Gram-negative bacteria after 20 passages.

Thermoresponsive polymer nanocarriers for biomedical applications

Polymer nanocarriers allow drug encapsulation leading to fragile molecule protection from early degradation/metabolization, increased solubility of poorly soluble drugs and improved plasmatic half-life. However, efficiently controlling the drug release from nanocarriers is still challenging. Thermoresponsive polymers exhibiting either a lower critical solution temperature (LCST) or an upper critical solution temperature (UCST) in aqueous medium may be the key to build spatially and temporally controlled drug delivery systems. In this review, we provide an overview of LCST and UCST polymers used as building blocks for thermoresponsive nanocarriers for biomedical applications. Recent nanocarriers based on thermoresponsive polymer exhibiting unprecedented features useful for biomedical applications are also discussed. While LCST nanocarriers have been studied for over two decades, UCST nanocarriers have recently emerged and already show great potential for effective thermoresponsive drug release.

Cyclodextrin-Based Star-Like Amphiphilic Cationic Polymer as a Potential Pharmaceutical Carrier in Macrophages

Effective delivery of therapeutic genes or small molecular drugs into macrophages is important for cell based immune therapy, but it remains a challenge due to the intracellular reactive oxygen species and endosomal degradation of therapeutics inside immune cells. In this report, the star-like amphiphilic biocompatible β-cyclodextrin-graft-(poly(ε-caprolactone)-block-poly(2-(dimethylamino) ethyl methacrylate)_x (β-CD-g-(PCL-b-PDMAEMA)_x ) copolymer, consisting of a biocompatible cyclodextrin core, hydrophobic poly(ε-caprolactone) PCL segments and hydrophilic PDMAEMA blocks with positive charge, is optimized to achieve high efficiency gene transfection with enhanced stability, due to the micelle formation by hydrophobic PCL segments. In comparison with lipofetamine, a currently popular nonviral gene carrier, β-CD-g-(PCL-b-PDMAEMA)_x copolymer, shows better transfection efficiency of plasmid desoxyribose nucleic acid in RAW264.7 macrophages. More interestingly, this delivery platform by β-CD-g-(PCL-b-PDMAEMA)_x not only shows low toxicity but also better dexamethasone delivery efficiency, which might indicate its great potential in immunotherapy.

Amphiphilic prodrug-decorated graphene oxide as a multi-functional drug delivery system for efficient cancer therapy

Graphene oxide (GO) has shown great potential in drug delivery. However, the aqueous stability, non-specific drug release and slow release rate are major problems of the GO-based drug delivery system. Herein, we for the first time integrate the dispersant, stabilizing agent and active targeting carrier into a novel drug delivery system based on GO/PP-SS-DOX nanohybrids. The redox-sensitive PP-SS-DOX prodrug was obtained by conjugating mPEG-PLGA (PP) with doxorubicin (DOX) via disulfide bond. PEG-FA provided active targeting property for the constructed drug delivery system, GO/PP-SS-DOX/PEG-FA. In this demonstrated system, PP-SS-DOX markedly increases the stability in physiological solutions of GO and guarantees the DOX release in the reductive environment (cancerous cells). And PEG-FA helps target to cancerous tissues and induces FR-mediated endocytosis. In vitro drug release exhibited the obvious reductive sensitivity and the cumulative release amount was up to 90%, while 40% in previous reports within 72 h. The in vitro cytotoxicity of targeting nanohybrids was significantly cytotoxic than that of non-targeting nanohybrids. In vivo results displayed that the as-prepared targeting nanohybrids showed efficacious antitumor effect while it had nearly no systemic adverse toxicity on B16 tumor-bearing mice. Therefore, the in vitro and in vivo results indicate that our constructed GO/PP-SS-DOX/PEG-FA drug delivery system is a promising carrier in cancer therapy.

Supramolecular assemblies of alkane functionalized polyethylene glycol copolymers for drug delivery

Surfactants are commonly used drug carriers, however, there is a lack of understanding regarding the relationship between drug loading, drug release kinetics, and cell internalization with the physicochemical properties of the drug carriers, preventing rational design. The effects of altering hydrophobic and hydrophilic chain lengths on a poly[poly-(oxyethylene)-oxy-5-hydroxyisophthaloyl] (Ppeg) platform for delivering hydrophobic drugs was examined. The synthesized polymers were characterized by nuclear magnetic resonance spectroscopy (NMR), dynamic light scattering (DLS), and zeta potential. The resulting polymer particles were able to form micelles in aqueous solution and encapsulate pyrene, a highly hydrophobic model drug, with a loading capacity up to 8wt%, corresponding to a 50% loading efficiency. The ability to sustain drug release from these micelles over several days was also observed. RAW 264.7 macrophage uptake of the micelles was measured quantitatively and was found to be substantially higher than internalization of the unencapsulated drug. The loading capacity of the drug in the various micelles did not correlate with the internalization of the particles into the cells. Factorial analysis was used to develop predictive equations for drug loading, drug release kinetics, and cell internalization. These models were validated with newly synthesized compounds.

A review of recent progress in drug and protein encapsulation: Approaches, applications and challenges

Many drugs and proteins formulated for treatment of various diseases are not fully utilised due to environmentally problems such as degradation by enzymes or it being hydrophobic. To counter this problem, the drug and protein of interest are encapsulated by synthetic polymers where they are protected from the environment. This allows the molecule to reach its target safely and maximise its function. In this paper, we will discuss about the different techniques of encapsulation that includes emulsion evaporation, self-emulsifying drug delivery system and supercritical fluid. This will be followed by the drugs and proteins that are commonly encapsulated to counter life-threatening diseases such as cancer and diabetes. A novel method using foam was proposed and will be briefly discussed as it can play a huge role in future developments.

Overcoming STC2 mediated drug resistance through drug and gene co-delivery by PHB-PDMAEMA cationic polyester in liver cancer cells

Stanniocalcin 2 (STC2) overexpression in hepatocellular carcinoma (HCC) could lead to poor prognosis, which might be due to its induced P-glycoprotein and Bcl-2 protein expression level increase. P-glycoprotein or membrane pump induced drug efflux and altered prosurvival Bcl-2 expression are key mechanisms for drug resistance leading to failure of chemotherapy in HCC. However, current strategy to overcome both P-glycoprotein and Bcl-2 protein induced drug resistance was rarely reported. In this work, we utilized an amphiphilic poly[(R)-3-hydroxybutyrate] (PHB)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) cationic polyester to encapsulate chemotherapeutic paclitaxel (PTX) in hydrophobic PHB domain and Bcl-2 convertor Nur77/ΔDBD gene (Nur77 without DNA binding domain for mitochondria localization) by formation of polyplex due to cationic PDMAEMA segment, to effectively inhibit the drug resistant HepG2/STC2 and SMCC7721/STC2 liver cancer cell growth. Thanks to the cationic nanoparticle complex formation ability and high transfection efficiency to express Bcl-2 conversion proteins, PHB-PDMAEMA/PTX@polyplex could partially impair P-glycoprotein induced PTX efflux and activate the apoptotic function of previous prosurvival Bcl-2 protein. This is the pioneer report of cationic amphiphilic polyester PHB-PDMAEMA to codeliver anticancer drug and therapeutic plasmid to overcome both pump and non-pump mediated chemotherapeutic resistance in liver cancer cells, which might be inspiring for the application of polyester in personalized cancer therapy.

Acetal-linked PEGylated paclitaxel prodrugs forming free-paclitaxel-loaded pH-responsive micelles with high drug loading capacity and improved drug delivery

Endosomal pH-responsive micellar nanoparticles were prepared by self-assembly of an amphiphilic poly(ethylene glycol)-acetal-paclitaxel (PEG-acetal-PTX) prodrug, and free PTX could be encapsulated in the hydrophobic core of the nanoparticles. These nanoparticles exhibited excellent storage stability for over 6months under normal conditions, but disassembled quickly in response to faintly acidic environment. Incorporating physical encapsulation and chemical conjugation, the PTX concentration in the nanoparticles solution could reach as high as 3665μg/mL, accompanying with a high drug loading capacity of 60.3%. Additionally, benefitting from the difference in drug release mechanism and rate between encapsulated PTX and conjugated PTX, a programmed drug release behavior was observed, which may result in higher intracellular drug concentration and longer action time. CCK-8 assays showed that the nanoparticles demonstrated superior antitumor activity than free PTX against both HeLa and MDA-MB-231 cells. These prodrug-based nanomedicines have a great potential in developing translational PTX formulations for cancer therapy.

pH-triggered degradable polymeric micelles for targeted anti-tumor drug delivery

2-(Octadecyloxy)-1,3-dioxan-5-amine (OD) with an acid degradable ortho ester group was synthesized, and conjugated to hyaluronic acid (HA) backbone to prepare pH-responsive and tumor-targeted hyaluronic acid-2-(octadecyloxy)-1,3-dioxan-5-amine (HOD) conjugates. ¹H NMR was used to confirm the structures of the OD and HOD. The studies of pH-responsive behavior showed that HOD micelles were stable under physiological conditions while they were degraded in the tumor acidic microenvironment. Doxorubicin (DOX)-loaded HOD micelles (DOX/HOD) with a narrow size distribution were prepared and characterized. The increased release of DOX from DOX/HOD micelles was presented at low pH condition. From in vitro cytotoxicity assays against MCF-7 cells, the blank micelles exhibited low cytotoxicity, but DOX/HOD micelles had the higher cytotoxicity than pH insensitive control and free DOX. Cellular uptake experiments and confocal images demonstrated that pH-sensitive DOX/HOD micelles could be internalized efficiently by CD44 receptor mediated endocytosis, and then DOX was rapidly released due to pH-induced degradable of OD to cell nucleus compared to the non-sensitive micelles. Furthermore, endocytosis inhibition studies presented that DOX/HOD micelles were internalized into cells mainly via caveolae-mediated routes. In vivo study of micelles in tumor-bearing mice indicates that HOD micelles were more effectively accumulated into the tumor tissue than HOA micelles. These results verify that the pH-sensitive HOD micellar system is a promising nanocarrier for enhanced internalization of antitumor drugs to cancer cells.

Construction of biodegradable and biocompatible AIE-active fluorescent polymeric nanoparticles by Ce(IV)/HNO3 redox polymerization in aqueous solution

Aggregation-induced emission (AIE) active fluorescence polymeric nanoparticles (FPNs) have recently received increasing interests for biomedical applications such as cell imaging, drug delivery, disease diagnosis and treatment. Fabricated strategies of AIE-active FPNs with high efficiency, simplification and tenderness are still passionately pursued to promote the development of theranostic systems. In this work, we develop a facile method for the preparation of AIE-active FPNs by adopting Ce(IV)/HNO₃ redox polymerization under near room temperature. Thus-prepared FPNs (named as PEG-PLC-1) possess unique AIE feature, great water dispersity, excellent biocompatibility and biodegradability because of the conjugation of ultra-bright AIE dye (PhE-alc) and biodegradable PEG-PCL linear copolymers. The ¹H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), UV-Visible and fluorescence spectrometers were used to confirm the successful fabrication of AIE-active FPNs. Cell viability and cellular uptake behavior of PEG-PLC-1 FPNs were further investigated for their potential biomedical applications. Results demonstrated that PEG-PLC-1 FPNs are high water dispersity, intensive luminescence and low cytotoxicity, making them very attractive for biomedical applications. More importantly, the method for the fabrication of AIE-active biodegradable FPNs can be occurred under rather facile conditions (e.g., low temperature, free of metal catalysts, common chain transfer agent and aqueous solution) and are specially used for fabrication of AIE-active polysaccharides with poor organic solubility.

Antibacterial Performance of a PCL-PDMAEMA Blend Nanofiber-Based Scaffold Enhanced with Immobilized Silver Nanoparticles

In the present study, nanofiber meshes (NFs), composed of polycaprolactone and poly[(2-dimethylamino)ethyl methacrylate] at 80/20 and 50/50 PCL/PDMAEMA blend ratios, were obtained through electrospinning. Silver nanoparticles (AgNPs) formed in situ were then immobilized on NF surfaces through adsorption processes at different pHs. It was possible to observe that the amount of NF-AgNPs can be tuned by changing the pH of AgNPs immobilization and the PCL/PDMAEMA ratio in the blend. The neat NF and NF-AgNPs were characterized with respect to their morphology and mechanical properties. The effects of AgNPs on the antibacterial activities and cytotoxicity of meshes were also evaluated. The antibacterial performance of such NF was improved by the presence of AgNPs. The NF-AgNPs presented good antibacterial effect against S. aureus and partial toxicity against E. coli and P. aeruginosa. Also, compared with neat PCL/PDMAEMA the NF-AgNPs presented lower cytotoxicity against VERO cells, showing their potential for applications in tissue engineering for different types of cell growth.

Recent Advances of Using Hybrid Nanocarriers in Remotely Controlled Therapeutic Delivery

The development of hybrid biomaterials has been attracting great attention in the design of materials for biomedicine. The nanosized level of inorganic and organic or even bioactive components can be combined into a single material by this approach, which has created entirely new advanced compositions with truly unique properties for drug delivery. The recent advances in using hybrid nanovehicles as remotely controlled therapeutic delivery carriers are summarized with respect to different nanostructures, including hybrid host-guest nanoconjugates, micelles, nanogels, core-shell nanoparticles, liposomes, mesoporous silica, and hollow nanoconstructions. In addition, the controlled release of guest molecules from these hybrid nanovehicles in response to various remote stimuli such as alternating magnetic field, near infrared, or ultrasound triggers is further summarized to introduce the different mechanisms of remotely triggered release behavior. Through proper chemical functionalization, the hybrid nanovehicle system can be further endowed with many new properties toward specific biomedical applications.

Nanodelivery systems for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

Synthetic oligodeoxynucleotides containing immunostimulatory CpG motif mimic bacterial DNA and are potent activator of innate and adaptive immune responses. Therefore, CpG ODNs have significant potentials as immunotherapeutic agent for treatment of infectious diseases, allergy and cancer. Many clinical trials involving CpG ODNs either used alone or as adjuvant have been initiated. However, delivery of CpG ODNs to target sites still remains a great challenge due to their extreme susceptibility to nuclease degradation in serum and poor cellular uptake. Chemical modification of CpG ODNs backbone can protect them against degradation by nucleases, but have raised concern regarding several severe side effects. Development of efficient CpG ODNs delivery systems to address these issues and enhance their immunostimulatory effect are highly desirable. In recent years, the emergence of nanotechnology has provided unprecedented opportunities to encapsulate CpG ODN into various nanocarriers or synthesize CpG ODNs nanostructures. This review provides an overview of the delivery systems based on nanomaterials and nanostructures newly developed for enhancing the immunostimulatory effect of CpG ODNs, together with a brief discussion on perspectives for future studies in this field.

Comb-like temperature-responsive polyhydroxyalkanoate-graft-poly(2-dimethylamino-ethylmethacrylate) for controllable protein adsorption

Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters produced by many bacteria grown on sustainable bio-resources such as glucose or fatty acids.

Small molecule therapeutic-loaded liposomes as therapeutic carriers: from development to clinical applications

In this review, various methods and mechanisms for encapsulation of small therapeutic molecules in liposomes for targeted delivery and triggered release, as well as their potential in the clinical uses, are discussed.

Utilising inorganic nanocarriers for gene delivery

The delivery of genetic materials into cells to elicit cellular response has been extensively studied by biomaterials scientists globally.