Targeted delivery of Bcl-2 conversion gene by MPEG-PCL-PEI-FA cationic copolymer to combat therapeutic resistant cancer

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.

Metabolic engineering of Halomonas bluephagenesis for production of five carbon molecular chemicals derived from L-lysine

5-Aminovaleric acid (5-AVA), 5-hydroxyvalerate (5HV), copolymer P(3HB-co-5HV) of 3-hydroxybutyrate (3HB) and 5HV were produced from L-lysine as a substrate by recombinant Halomonas bluephagenesis constructed based on codon optimization, deletions of competitive pathway and L-lysine export protein, and three copies of davBA genes encoding L-lysine monooxygenase (DavB) and 5-aminovaleramide amidohydrolase (DavA) inserted into its genome to form H. bluephagenesis YF117ΔgabT1+2, which produced 16.4 g L-1 and 67.4 g L-1 5-AVA in flask cultures and in 7 L bioreactor, respectively. It was able to de novo synthesize 5-AVA from glucose by L-lysine-overproducing H. bluephagenesis TD226. Corn steep liquor was used instead of yeast extract for cost reduction during the 5-AVA production. Using promoter engineering based on Pporin mutant library for downstream genes, H. bluephagenesis YF117 harboring pSEVA341-Pporin42-yqhDEC produced 6 g L-1 5HV in shake flask growth, while H. bluephagenesis YF117 harboring pSEVA341-Pporin42-yqhDEC-Pporin278-phaCRE-abfT synthesized 42 wt% P(3HB-co-4.8 mol% 5HV) under the same condition. Thus, H. bluephagenesis was successfully engineered to produce 5-AVA and 5HV in supernatant and intracellular P(3HB-co-5HV) utilizing L-lysine as the substrate.

Sustained release of therapeutic gene by injectable hydrogel for hepatocellular carcinoma

Gene therapy has shown remarkable effectiveness in the management of disease like cancer and inflammation as a revolutionary therapeutic. Nonetheless, therapeutic drug target discovery, efficient gene delivery, and gene delivery vehicles continue to be significant obstacles. Due to their effective gene transport capabilities and low immunogenicity, supramolecular polymers have garnered significant interest. Herein, ABHD5 is identified as a potential therapeutic target since it is dysregulated in hepatocellular carcinoma (HCC). Interestingly, the downregulation of ABHD5 could induce programmed death-ligand 1 (PD-L1) expression in liver cancer, which may contribute to the immunosuppression. To overcome the immunosuppression caused by PD-L1, an injectable hydrogel is designed to achieve efficient abhydrolase domain containing 5 (ABHD5) gene delivery via the host-guest interaction with branched polyethyleneimine-g-poly (ethylene glycol), poly (ethylene oxide) and poly (propylene oxide) block copolymers and α-CD (PPA/CD), demonstrating the capability for sustained gene release. The co-assembly hydrogel demonstrates good biocompatibility and enhanced gene transfection efficiency, efficiently triggering tumor cell apoptosis. Overall, the results of this study suggest that ABHD5 is a potential therapeutic target, and that a host-guest-based supramolecular hydrogel could serve as a promising platform for the inhibition of HCC.

Developments on the Smart Hydrogel-Based Drug Delivery System for Oral Tumor Therapy

At present, an oral tumor is usually treated by surgery combined with preoperative or postoperative radiotherapies and chemotherapies. However, traditional chemotherapies frequently result in substantial toxic side effects, including bone marrow suppression, malfunction of the liver and kidneys, and neurotoxicity. As a new local drug delivery system, the smart drug delivery system based on hydrogel can control drug release in time and space, and effectively alleviate or avoid these problems. Environmentally responsive hydrogels for smart drug delivery could be triggered by temperature, photoelectricity, enzyme, and pH. An overview of the most recent research on smart hydrogels and their controlled-release drug delivery systems for the treatment of oral cancer is given in this review. It is anticipated that the local drug release method and environment-responsive benefits of smart hydrogels will offer a novel technique for the low-toxicity and highly effective treatment of oral malignancy.

Efficient delivery of the Bcl-2 antisense oligonucleotide G3139 via nucleus-targeted aCD33-NKSN nanoparticles

G3139 is an antisense oligodeoxyribonucleotide (ODN) developed as a Bcl-2 down-regulating agent for the treatment of acute myelogenous leukemia (AML). However, the clinical efficacy of G3139 has been shown to be limited due to its rapid plasma clearance and low permeability. To enhance the effective delivery of G3139, this work prepared a novel nano gene delivery vector (aCD33-NKSN) consisting of a CD33 antigbody (aCD33), a nuclear localization signal (NLS), gene fusion peptides (KALA), and stearic acid (SA) for CD33 antigen targeting and nuclear localization. The aCD33-NKSN/G3139 nanoparticles were spherical and uniformly sized with a positive charge and sustained release. They had an excellent G3139 loading capacity and colloidal stability. The aCD33-NKSN/G3139 delivered G3139 into the nucleus of Kasumi-1 cells and aCD33-NKSN/G3139 could more effectively inhibited Bcl-2 expression and induced apoptosis in Kasumi-1 cells versus free G3139. The aCD33-NKSN/G3139 administration was more effective at inhibiting tumor growth, and significantly prolonged the survival time of mice in contrast to free G3139. The results illustrate that aCD33-NKSN/G3139 nanoparticles could improve the antitumor activity of encapsulated G3139 due to aCD33 targeting and the ability to perform nuclear localization, The results offer a promising clinical application potential for the treatment of acute myeloid leukemia.

Construction of a Silver Nanoparticle Complex and its Application in Cancer Treatment

Nanomedicine has been used in tumor treatment and research due to its advantages of targeting, controlled release and high absorption rate. Silver nanoparticle (AgNPs), with the advantages of small particle size, and large specific surface area, are of great potential value in suppressing and killing cancer cells. Methods: AgNPs–polyethyleneimine (PEI) –folate (FA) (AgNPs–PF) were synthesised and characterised by several analytical techniques. The ovarian cancer cell line Skov3 was used as the cell model to detect the tumor treatment activity of AgNPs, AgNPs–PF and AgNPs+ AgNPs–PF. Results: Results shown that AgNPs–PF were successfully constructed with uniform particle size of 50–70 nm. AgNPs, AgNPs–PF, AgNPs–PF+ AgNPs all showed a certain ability to inhibit cancer cell proliferation, increase reactive oxygen species and decrease the mitochondrial membrane potential. All AgNPs, AgNPs–PF, AgNPs+ AgNPs–PF promoted DNA damage in Skov3 cells, accompanied by the generation of histone RAD51 and γ-H2AX site, and eventually leading to the apoptosis of Skov3 cells. The combination of AgNPs–PF and AgNPs had a more pronounced effect than either material alone. Conclusion: This study is to report that the combination of AgNPs+ AgNPs–PF can cause stronger cytotoxicity and induce significantly greater cell death compared to AgNPs or AgNPs–PF alone in Skov3 cells. Therefore, the combined application of drugs could be the best way to cancer treatment.

Glass Transition Temperature of PLGA Particles and the Influence on Drug Delivery Applications

Over recent decades, poly(lactic-co-glycolic acid) (PLGA) based nano- and micro- drug delivery vehicles have been rapidly developed since PLGA was approved by the Food and Drug Administration (FDA). Common factors that influence PLGA particle properties have been extensively studied by researchers, such as particle size, polydispersity index (PDI), surface morphology, zeta potential, and drug loading efficiency. These properties have all been found to be key factors for determining the drug release kinetics of the drug delivery particles. For drug delivery applications the drug release behavior is a critical property, and PLGA drug delivery systems are still plagued with the issue of burst release when a large portion of the drug is suddenly released from the particle rather than the controlled release the particles are designed for. Other properties of the particles can play a role in the drug release behavior, such as the glass transition temperature (T_g). The T_g, however, is an underreported property of current PLGA based drug delivery systems. This review summarizes the basic knowledge of the glass transition temperature in PLGA particles, the factors that influence the T_g, the effect of T_g on drug release behavior, and presents the recent awareness of the influence of T_g on drug delivery applications.

Engineering nanotheranostic strategies for liver cancer

The incidence and mortality of hepatocellular carcinoma have continued to increase over the last few years, and the medicine-based outlook of patients is poor. Given great ideas from the development of nanotechnology in medicine, especially the advantages in the treatments of liver cancer. Some engineering nanoparticles with active targeting, ligand modification, and passive targeting capacity achieve efficient drug delivery to tumor cells. In addition, the behavior of drug release is also applied to the drug loading nanosystem based on the tumor microenvironment. Considering clinical use of local treatment of liver cancer, in situ drug delivery of nanogels is also fully studied in orthotopic chemotherapy, radiotherapy, and ablation therapy. Furthermore, novel therapies including gene therapy, phototherapy, and immunotherapy are also applied as combined therapy for liver cancer. Engineering nonviral polymers to function as gene delivery vectors with increased efficiency and specificity, and strategies of co-delivery of therapeutic genes and drugs show great therapeutic effect against liver tumors, including drug-resistant tumors. Phototherapy is also applied in surgical procedures, chemotherapy, and immunotherapy. Combination strategies significantly enhance therapeutic effects and decrease side effects. Overall, the application of nanotechnology could bring a revolutionary change to the current treatment of liver cancer.

A review of the tortuous path of nonviral gene delivery and recent progress

Gene therapy encompasses the transfer of exogenous genetic materials into the patient's target cells to treat or prevent diseases. Nevertheless, the transfer of genetic material into desired cells is challenging and often requires specialized tools or delivery systems. For the past 40 years, scientists are mainly pursuing various viruses as gene delivery vectors, and the overall progress has been slow and far from the expectation. As an alternative, nonviral vectors have gained substantial attention due to their several advantages, including superior safety profile, enhanced payload capacity, and stealth abilities. Since nonviral vectors encounter multiple extra- and intra-cellular barriers limiting the transfer of genetic payload into the target cell nucleus, we have discussed these barriers in detail for this review. A direct approach, utilizing physical methods like electroporation, sonoporation, gene gun, eliminate the requirement for a specific carrier for gene delivery. In contrast, chemical methods of gene transfer exploit natural or synthetic compounds as carriers to increase cellular targeting and gene therapy effectiveness. We have also emphasized the recent advancements aimed at enhancing the current nonviral approaches. Therefore, in this review, we have focused on discussing the current evolving state of nonviral gene delivery systems and their future perspectives.

T cell membrane cloaking tumor microenvironment-responsive nanoparticles with a smart "membrane escape mechanism" for enhanced immune-chemotherapy of melanoma

The application of combination immune-chemotherapy makes up for the limitation of monotherapy and achieves superior antitumor activity against cancer. However, combinational therapy is always restricted by poor tumor targeted drug delivery efficacy. Herein, novel T cell membrane cloaking tumor microenvironment-responsive nanoparticles (PBA modified T cell membrane cloaking hyaluronic acid (HA)-disulfide bond-vitamin E succinate/curcumin, shortened as RCM@T) were developed. T cell membrane cloaking not only serves as a protection shell for sufficient drug delivery but also acts as a programmed cell death-1(PD-1) "antibody" to selectively bind the PD-L1 of tumor cells. When RCM@T is intravenously administrated into the blood stream, it accumulates at tumor sites and responds to an acidic pH to achieve a "membrane escape effect" and expose the HA residues of RCM for tumor targeted drug delivery. RCM accumulates in the cytoplasm via CD44 receptor mediated endocytosis and intracellularly releases antitumor drug in the intracellular redox microenvironment for tumor chemotherapy. T cell membrane debris targets the PD-L1of tumor cells for tumor immunotherapy, which not only directly kills tumor cells, but also improves the CD8+ T cell level and facilitates effector cytokine release. Taken together, the as-constructed RCM@T creates a new way for the rational design of a drug delivery system via the combination of stimuli-responsive drug release, chemotherapeutical agent delivery and cell membrane based immune checkpoint blockade immunotherapy.

Rational Design of Hyaluronic Acid-Based Copolymer-Mixed Micelle in Combination PD-L1 Immune Checkpoint Blockade for Enhanced Chemo-Immunotherapy of Melanoma

The application of combinational therapy breaks the limitation of monotherapy and achieves better clinical benefit for tumor therapy. Herein, a hyaluronic acid/Pluronic F68-based copolymer-mixed micelle was constructed for targeted delivery of chemotherapeutical agent docetaxel (PHDM) in combination with programmed cell death ligand-1(PD-L1) antibody. When PHDM+anti-PDL1 was injected into the blood system, PHDM could accumulate into tumor sites and target tumor cells via CD44-mediated endocytosis and possess tumor chemotherapy. While anti-PDL1 could target PD-L1 protein expressed on surface of tumor cells to the immune checkpoint blockade characteristic for tumor immunotherapy. This strategy could not only directly kill tumor cells but also improve CD8+ T cell level and facilitate effector cytokines release. In conclusion, the rational-designed PHDM+anti-PDL1 therapy strategy creates a new way for tumor immune-chemotherapy.

Micellar Carriers Based on Amphiphilic PEG/PCL Graft Copolymers for Delivery of Active Substances

Amphiphilic copolymers of alkyne functionalized 2-hydroxyethyl methacrylate (AlHEMA) and poly(ethylene glycol) methyl ether methacrylate (MPEGMA) with graft or V-shaped graft topologies were synthesized. The functionalization of poly(ε-caprolactone) (PCL) with azide group enabled attachment to P(AlHEMA-co-MPEGMA) copolymers via a "click" alkyne-azide reaction. The introduction of PCL as a second side chain type in addition to PEG resulted in heterografted copolymers with modified properties such as biodegradability. "Click" reactions were carried out with efficiencies between 17-70% or 32-50% (for lower molecular weight PCL, 4000 g/mol, or higher molecular weight PCL, 9000 g/mol, respectively) depending on the PEG grafting density. The graft copolymers were self-assembled into micellar superstructures with the ability to encapsulate active substances, such as vitamin C (VitC), arbutin (ARB) or 4-n-butylresorcinol (4nBRE). Drug loading contents (DLC) were obtained in the range of 5-55% (VitC), 39-91% (ARB) and 42-98% (4nBRE). In vitro studies carried out in a phosphate buffer saline (PBS) solution (at pH 7.4 or 5.5) gave the maximum release levels of active substances after 10-240 min depending on the polymer system. Permeation tests in Franz chambers indicated that the bioactive substances after release by micellar systems penetrated through the artificial skin membrane in small amounts, and a majority of the bioactive substances remained inside the membrane, which is satisfactory for most cosmetic applications.

Supramolecular hydrogel containing multi-generation poly(L-lysine) dendrons for sustained co-delivery of docetaxel and matrix metallopeptidase-9 short hairpin RNA plasmid

To obtain an efficient drug and gene co-delivery hydrogel, methoxy polyethylene glycol was reacted with the caprolactone units to form the MPEG-PCL block copolymer through the polymerization reaction, which is amphiphilic and can load the hydrophobic drugs. Then, MPEG-PCL conjugated with a multi-generation poly(L-lysine) dendron to form the guest molecule MPEG-PCL-PLLD. After interacted with α-cyclodextrin through host–guest inclusion, the drug and gene dual carrier of supramolecular hydrogel was obtained. The physical properties of the hydrogel, such as the gelation time, the hydrogel strength, or its shear viscosity, could be modulated by the hose molecule of α-cyclodextrin content. MPEG-PCL-PLLD could co-load the drug and gene effectively. After gelation, the loaded drug and gene could be released sustainedly, and the release rate of them was also modulated by the α-cyclodextrin content. The supramolecular hydrogel showed a sustained effect on tumor cells and could induce the cell apoptosis sustainedly. Moreover, the co-delivery strategy was superior to only drug or gene used in tumor cell inhibition. This supramolecular hydrogel as the high-efficiency and sustained co-delivery system showed a promising application in a long-term tumor therapy.

Self-Healable, Fast Responsive Poly(ω-Pentadecalactone) Thermogelling System for Effective Liver Cancer Therapy

A polyurethane based thermogelling system comprising poly(ω-pentadecalactone) (PPDL), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG), termed as PDEP, was synthesized. The incorporation of PPDL lowers critical micelle concentration (CMC) as well as critical gelation concentration (CGC) of the novel copolymers compared to commercial Pluronic® F127. The thermogels showed excellent thermal stability at high temperature up to 80°C, fast response to temperature change in a time frame of less than second, as well as remarkable self-healing properties after being broken at high strain. In vitro drug release studies using docetaxel (DTX) and cell uptake studies using doxorubicin (DOX) show high potential of the hydrogel as drug reservoir for sustainable release profile of payloads, while the in vivo anti-tumor evaluation using mice model of hepatocellular carcinoma further demonstrated the significant inhibition on the growth of tumor. Together with its excellent biocompatibility in different organs, the novel PDPE thermogelling copolymers reported in this work could potentially be utilized as in situ-forming hydrogels for liver cancer therapy.

Recent advances in polymeric materials for the delivery of RNA therapeutics

Introduction: The delivery of nucleic acid therapeutics through non-viral carriers face multiple biological barriers that reduce their therapeutic efficiency. Despite great progress, there remains a significant technological gap that continues to limit clinical translation of these nanocarriers. A number of polymeric materials are being exploited to efficiently deliver nucleic acids and achieve therapeutic effects. Areas covered: We discuss the recent advances in the polymeric materials for the delivery of nucleic acid therapeutics. We examine the use of common polymer architectures and highlight the challenges that exist for their development from bench side to clinic. We also provide an overview of the most notable improvements made to circumvent such challenges, including structural modification and stimuli-responsive approaches, for safe and effective nucleic acid delivery. Expert opinion: It has become apparent that a universal carrier that follows 'one-size' fits all model cannot be expected for delivery of all nucleic acid therapeutics. Carriers need to be designed to exhibit sensitivity and specificity toward individual targets diseases/indications, and relevant subcellular compartments, each of which possess their own unique challenges. The ability to devise synthetic methods that control the molecular architecture enables the future development that allow for the construction of 'intelligent' designs.

Light-Induced Redox-Responsive Smart Drug Delivery System by Using Selenium-Containing Polymer@MOF Shell/Core Nanocomposite

Rational design of controllable drug release systems is important for tumor treatments due to the nonspecific toxicity of many chemotherapeutics. Herein, laser or light responsive pharmaceutical delivery nanoparticles are designed, by taking the advantages of redox responsive selenium (Se) substituted polymer as shell and photosensitive porphyrin zirconium metal-organic frameworks (MOF) as core. In detail, redox cleavable di-(1-hydroxylundecyl) selenide (DH-Se), biocompatible poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) are randomly polymerized to form poly(DH-Se/PEG/PPG urethane), which is used to coat the reactive oxygen species' (ROS) producible porous porphyrin zirconium metal organization formulation (PCN-224 MOF) to form the final poly(DH-Se/PEG/PPG urethane)@MOF shell-core nanoparticle with spherical shape by emulsion approach. Interestingly, poly(DH-Se/PEG/PPG urethane)@MOF nanoparticles with loading of chemotherapeutic doxorubicin (DOX) experience a fast and controllable release, which can realize the combination of chemotherapy and photodynamic therapy upon irradiation with laser light, due to the light-triggered ROS production by MOF which further causes the cleavage of poly(DH-Se/PEG/PPG urethane) polymer chain and the release of encapsulated DOX. To the best of the authors' knowledge, this is the first design of utilizing MOF and selenium substituted polymer as controllable drug release carriers, which might be beneficial for precise chemotherapy and photodynamic therapy combination.

Recent Advances on Polymeric Beads or Hydrogels as Embolization Agents for Improved Transcatheter Arterial Chemoembolization (TACE)

Transcatheter arterial chemoembolization (TACE), aiming to block the hepatic artery for inhibiting tumor blood supply, became a popular therapy for hepatocellular carcinoma (HCC) patients. Traditional TACE formulation of anticancer drug emulsion in ethiodized oil (i.e., Lipiodol®) and gelatin sponge (i.e., Gelfoam®) had drawbacks on patient tolerance and resulted in undesired systemic toxicity, which were both significantly improved by polymeric beads, microparticles, or hydrogels by taking advantage of the elegant design of biocompatible or biodegradable polymers, especially amphiphilic polymers or polymers with both hydrophilic and hydrophobic chains, which could self-assemble into proposed microspheres or hydrogels. In this review, we aimed to summarize recent advances on polymeric embolization beads or hydrogels as TACE agents, with emphasis on their material basis of polymer architectures, which are important but have not yet been comprehensively summarized.

3D printing of mesoporous bioactive glass/silk fibroin composite scaffolds for bone tissue engineering

The fabrication of bone tissue engineering scaffolds with high osteogenic ability and favorable mechanical properties is of huge interest. In this study, a silk fibroin (SF) solution of 30 wt% was extracted from cocoons and combined with mesoporous bioactive glass (MBG) to fabricate MBG/SF composite scaffolds by 3D printing. The porosity, compressive strength, degradation and apatite forming ability were evaluated. The results illustrated that MBG/SF scaffolds had superior compressive strength (ca. 20 MPa) and good biocompatibility, and stimulated bone formation ability compared to mesoporous bioactive glass/polycaprolactone (MBG/PCL) scaffolds. We subcutaneously transplanted hBMSCs-loaded MBG/SF and MBG/PCL scaffolds into the back of nude mice to evaluate heterotopic bone formation assay in vivo, and the results revealed that the gene expression levels of common osteogenic biomarkers on MBG/SF scaffolds were significantly better than MBG/PCL scaffolds. These results showed that 3D-printed MBG/SF composite scaffolds are great promising for bone tissue engineering.

Poly(ethylene glycol)- block-poly(2-aminoethyl methacrylate hydrochloride)-Based Polyplexes as Serum-Tolerant Nanosystems for Enhanced Gene Delivery

Incorporation of poly(ethylene glycol) (PEG) into polyplexes has been used as a promising approach to enhance their stability and reduce unwanted interactions with biomolecules. However, this strategy generally has a negative influence on cellular uptake and, consequently, on transfection of target cells. In this work, we explore the effect of PEGylation on biological and physicochemical properties of poly(2-aminoethyl methacrylate) (PAMA)-based polyplexes. For this purpose, different tailor-made PEG- b-PAMA block copolymers, and the respective homopolymers, were synthesized using the controlled/"living" radical polymerization method based on activators regenerated by electron transfer atom transfer radical polymerization. The obtained data show that PEG- b-PAMA-based polyplexes exhibited a much better transfection activity/cytotoxicity relationship than the corresponding non-PEGylated nanocarriers. The best formulation, prepared with the largest block copolymer (PEG₄₅- b-PAMA₁₆₈) at a 25:1 N/P ratio, presented a 350-fold higher transfection activity in the presence of serum than that obtained with polyplexes generated with the gold standard bPEI. This higher transfection activity was associated to an improved capability to overcome the intracellular barriers, namely the release from the endolysosomal pathway and the vector unpacking and consequent DNA release from the nanosystem inside cells. Moreover, these nanocarriers exhibit suitable physicochemical properties for gene delivery, namely reduced sizes, high DNA protection, and colloidal stability. Overall, these findings demonstrate the high potential of the PEG₄₅- b-PAMA₁₆₈ block copolymer as a gene delivery system.

Recent Progress in Macromolecule-Anchored Hybrid Gold Nanomaterials for Biomedical Applications

Gold nanoparticles (AuNPs), with elegant thermal, optical, or chemical properties due to quantum size effects, may serve as unique species for therapeutic or diagnostic applications. It is worth mentioning that their small size also results in high surface activity, leading to significantly impaired stability, which greatly hinders their biomedical utilizations. To overcome this problem, various types of macromolecular materials are utilized to anchor AuNPs so as to achieve advanced synergistic effect by dispersing, protecting, and stabilizing the AuNPs in polymeric-Au hybrid self-assemblies. In this review, the most recent development of polymer-AuNP hybrid systems, including AuNPs@polymeric nanoparticles, AuNPs@polymeric micelle, AuNPs@polymeric film, and AuNPs@polymeric hydrogel are discussed with respect to their different synthetic strategies. These sophisticated materials with diverse functions, oriented toward biomedical applications, are further summarized into several active domains in the areas of drug delivery, gene delivery, photothermal therapy, antibacterials, bioimaging, etc. Finally, the possible approaches for future design of multifunctional polymer-AuNP hybrids by combining hybrid chemistry with biological interface science are proposed.

Using Artificial Skin Devices as Skin Replacements: Insights into Superficial Treatment

Artificial skin devices are able to mimic the flexibility and sensory perception abilities of the skin. They have thus garnered attention in the biomedical field as potential skin replacements. This Review delves into issues pertaining to these skin-deep devices. It first elaborates on the roles that these devices have to fulfill as skin replacements, and identify strategies that are used to achieve such functionality. Following which, a comparison is done between the current state of these skin-deep devices and that of natural skin. Finally, an outlook on artificial skin devices is presented, which discusses how complementary technologies can create skin enhancements, and what challenges face such devices.

A review of emerging bone tissue engineering via PEG conjugated biodegradable amphiphilic copolymers

Defects in bones can be caused by a plethora of reasons, such as trauma or illness, and in many cases, it poses challenges to the current treatment approaches for bone repair. With increasing demand of bone bioengineering in tissue transplant, there is a need to source for sustainable solutions to induce bone regeneration. Polymeric biomaterials have been identified as a promising approach due to its excellent biocompatibility and controllable biodegradability. Specifically, poly(ethylene glycol) (PEG) is one of the most commonly investigated polymer for use in bio-related application due to its bioinertness and versatility. Furthermore, the hydrophilic nature enables it to be incorporated with hydrophobic but biodegradable polymers like, polylactide (PLA) and polycaprolactone (PCL), to create an amphiphilic polymer. This article reviews the recent synthetic strategies available for the construction of PEG conjugated polymeric system, analysis of PEG influence on the material properties, and provides an overview of its application in bone engineering.

Zinc ion coordination significantly improved the transfection efficiency of low molecular weight polyethylenimine

A zinc ion coordination-contained polycationic gene delivery system.

Surfactant Free Delivery of Docetaxel by Poly[(R)-3-hydroxybutyrate-(R)-3-hydroxyhexanoate]-Based Polymeric Micelles for Effective Melanoma Treatments

Docetaxel (DTX) is a new semisynthetic chemical in the taxoid family and serves a wide spectrum of chemotherapeutics. Current commercial formulation of DTX is based on the addition of the nonionic surfactants (i.e., ethanol and Tween 80), which are reported to cause severe hemolysis, hypersensitivity reactions, or neurotoxic toxicity and greatly hinders patient tolerance or compliance. In this report, a novel low-toxic, biodegradable, and amphiphilic poly[(R)-3-hydroxybutyrate-(R)-3-hydroxyhexanoate] (PHBHx)-based polyurethane (a copolymer made of hydrophobic PHBHx with biocompatible D-3-hydroxybutyric acid as degradation product, thermosensitive polypropylene glycol (PPG), and hydrophilic polyethylene glycol (PEG) segments) with nanosized micelle formation ability to encapsulate DTX, as a surfactant free formulation, is reported. Interestingly, this DTX-loaded poly(PHBHx/PEG/PPG urethane) micelle formulation with >90% drug loading efficiency shows significantly improved DTX solubility in aqueous medium, reduced hemolysis for better blood compatibility, and increased drug uptake in A375 melanoma cells, which provides the possibility of systematic delivery of DTX. As a proof-of-concept, an A375 melanoma xenograft mouse model is established to verify the therapeutic effect of this DTX-loaded poly(PHBHx/PEG/PPG urethane) micelle formulation, indicating the promising application of PHBHx-based polymeric nanosized micelle as a surfactant free formulation of chemotherapeutics which might greatly be beneficial for controllable delivery of pharmaceutics and cancer therapy.

Biodegradable polyester unimolecular systems as emerging materials for therapeutic applications

Unimolecular micelles, as a class of single-molecular micelles, are structurally stable regardless of their concentrations or alterations of the outer environment such as pH, temperature, ion strength etc. in comparison with conventional polymeric micelles. Polyester unimolecular micelles are extensively applied in bio-medical fields because of their stability, biocompatibility, biodegradability, structural-controllabilty etc. In this review, the most recent developments in polyester unimolecular micelle designs in terms of Boltorn polymer H40 core, cyclodextrin, dendrimer or dendrimer-like polymer, or polyhedral oligomeric silsesquioxane (POSS) based polyester unimolecular micelles are presented. The significance and application in biomedical fields including drug delivery, bio-imaging and theranostics are also classified in this review. Finally, the remaining challenges and future perspectives for further development of unimolecular micelles as therapeutic materials are also discussed.

Targeted and Sustained Corelease of Chemotherapeutics and Gene by Injectable Supramolecular Hydrogel for Drug-Resistant Cancer Therapy

Coadministration of chemotherapeutics as well as therapeutic gene could play a synergistic effect on cancer treatment. It is noteworthy that targeted and sustained codelivery of chemotherapeutic and therapeutic gene was rarely achieved in previous reports, while it might serve as an important platform for treating solid tumor with possible surrounding lesions. Herein, an injectable supramolecular hydrogel formed by α-cyclodextrin (α-CD) and cationic amphiphilic copolymer made of methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(ethylene imine) with folic acid targeted group (MPEG-PCL-PEI-FA), is rationally designed to achieve sustained codelivery of chemotherapeutic paclitaxel (PTX) and B-cell lymphoma-2 (Bcl-2) conversion gene Nur77 in the form of nanocomplex up to 7 days, to effectively inhibit the growth of folate receptor overexpressing H460/Bcl-2 therapeutic-resistant tumors (induced by overexpression of anti-apoptotic Bcl-2 protein), with peritumoral injection rather than direct intratumoral injection of hydrogel. To the best of our knowledge, this is a pioneer report on injectable MPEG-PCL-PEI-FA/α-CD supramolecular hydrogel with the ability to codeliver and sustainedly release PTX and Nur77 gene to combat Bcl-2 overexpressed therapeutic-resistant tumors in a targeted manner, which might be beneficial for further design in personalized medicine.

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.

Synergistic Lysosomal Activatable Polymeric Nanoprobe Encapsulating pH Sensitive Imidazole Derivative for Tumor Diagnosis

Developing optical tumor imaging probes with minimal background noise is very important for its early detection of small lesions and accurate diagnosis of cancer. To overcome the bottleneck of low signal to noise ratio and sensitivity, it needs further improvement in fluorescent probe design and understanding of tumor development process. Recent reports reveal that lysosome's acidity in cancer cells can be below 4.5 with high Na⁺ /H⁺ exchange activity, which makes it an ideal target intracellular organelle for cancer diagnosis based on the variation of pH. Herein, a boron 2-(2'-pyridyl) imidazole complex derivative (BOPIM-N) is developed, with the ability to show a pH-activatable "OFF-ON" fluorescent switch by inhibiting twisted intramolecular charge transfer upon protonation at pH 3.8-4.5, which is studied for its selective viable cancer cell imaging ability in both in vitro and in vivo experiments. Interestingly, BOPIM-N can specifically emit green fluorescence in lysosomes of cancer cells, indicating its promising cancer cell specific imaging ability. More importantly, nanoformulated BOPIM-N probes can be specifically light-ON in tumor bearing site of nude mice with resolution up to cellular level, indicating its potential application in tumor diagnosis and precision medicine.

Dual Drug Delivery System Based on Biodegradable Organosilica Core-Shell Architectures

To overcome drug resistance, efficient cancer therapeutic strategies using a combination of small-molecule drugs and macromolecule drugs is highly desired. However, because of their significant differences in molecular weight and size, it is difficult to load them simultaneously in one vector and to release them individually. Here, a biodegradable organosilica-based core-shell-structured nanocapsule was designed and used as a dual stimuli-responsive drug vector to solve this problem. Biodegradable organosilica shell coated outside the macromolecule model drug "core" would be disrupted by high glutathione (GSH) levels inside tumor cells, resulting in the escape of the entrapped drugs. Small-molecule drugs capping on the surface of the organosilica shell via pH-responsive imine bonds can be cut and released in the acidic lysosomal environment. Transmission electron microscopy has shown that the framework of the organosilica shell was dissolved and degraded after 8 h incubation with 5 mM GSH. Confocal imaging confirmed that small-molecule and macromolecular drugs were individually released from the nanoparticles because of the pH or redox-triggered degradation under the tumor microenvironment and thus led to the strong fluorescence recovery in the cytoplasm. As expected, these biodegradable organosilica nanoparticles could not release drugs into normal cells but could specifically release them into tumor cells owing to their tumor-triggered targeting capability. This system will serve as an efficient shuttle for multidrug delivery and also provide a potential strategy to overcome drug resistance.

Hierarchically Self-Assembled Supramolecular Host-Guest Delivery System for Drug Resistant Cancer Therapy

In this report, a new star-like copolymer β-CD- g-(PNIPAAm- b-POEGA) _x, consisting of a β-CD core, grafted with temperature-responsive poly( N-isopropylacrylamide) (PNIPAAm) and biocompatible poly(oligo(ethylene glycol) acrylate) (POEGA) in a block copolymer of the arms, was used to deliver chemotherapeutics to drug resistant cancer cells and tumors. The first step of the self-assembly process involves the encapsulation of chemotherapeutics through host-guest inclusion complexation between the β-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded β-CD- g-(PNIPAAm- b-POEGA) _x/PTX inclusion complex to hierarchically self-assemble into nanosized supramolecular assemblies at 37 °C, whereas the presence of poly(ethylene glycol) (PEG) chains in the distal end of the star-like copolymer arms impart enhanced stability to the self-assembled structure. More interestingly, this supramolecular host-guest nanocomplex promoted the enhanced cellular uptake of chemotherapeutics in MDR-1 up-regulated drug resistant cancer cells and exhibited high therapeutic efficacy for suppressing drug resistant tumor growth in an in vivo mouse model, due to the increased stability, improvement in aqueous solubility, enhanced cellular uptake, and partial membrane pump impairment by taking the advantage of PEGylation and supramolecular complex between this star-like copolymer and chemotherapeutics. This work signifies that temperature-sensitive PEGylated supramolecular nanocarriers with good biocompatibility are effective in combating MDR-1 mediated drug resistance in both in vitro and in vivo models, which is of significant importance for the advanced drug delivery platform designed to combat drug resistant cancer.

Versatile Supermolecular Inclusion Complex Based on Host-Guest Interaction for Targeted Gene Delivery

A facile and targeted gene delivery system was prepared by conjugating β-cyclodextrin modified polyethylenimine (PEI-CD) and adamantyl peptide (AdGRGDS) based on host-guest interaction. With the rational design between PEI-CD and AdGRGDS, the PEI-CD/AdGRGDS gene delivery system showed excellent DNA binding capability and exhibited good ability to compact DNA into uniform spherical nanoparticles. In vitro luciferase assay showed that gene expression transfected by PEI-CD/AdGRGDS was stronger than that by PEI-CD in HeLa cells, whereas gene expression transfected by PEI-CD/AdGRGDS and PEI-CD was similar to each other in COS7 cells. Internalization of complexes was qualitatively studied using a confocal laser scanning microscope (CLSM) and quantitatively analyzed by flow cytometry, respectively, and targeting specificity was also evaluated by CLSM. Results of CLSM and flow cytometry indicated that PEI-CD/AdGRGDS had good targeting specificity to tumor cells with integrin αvβ3 overexpression. To further evaluate the targeting specificity and transfection efficiency in vivo, a rat model with murine hepatic carcinoma cell line H22 was used. PEI-CD/AdGRGDS showed stronger gene expression efficiency than PEI-CD via in vivo transfection of pORF-LacZ and pGL-3 plasmids after subcutaneous injection. Interestingly, PEI-CD/AdGRGDS also showed high targeting specificity and transfection distribution to tumor xenograft after tail-vein injection. In vitro and in vivo assays highlighted the importance of GRGDS targeting specificity to tumor cells with integrin αvβ3 overexpression and demonstrated that the PEI-CD/AdGRGDS gene delivery system would have great potential for targeted tumor therapy.

Recent advances in the development of biodegradable PHB-based toughening materials: Approaches, advantages and applications

Polyhydroxybutyrate (PHB) is a natural biodegradable polymer that is produced by many types of bacteria as an intracellular energy storage material. Due to its numerous advantages such as biodegradability, biocompatibility, availability and with physical properties comparable to petroleum-based thermoplastics, PHB is a potential substitute in biomedical and packaging fields. However, several physical drawbacks, such as high production cost, thermal instability, and poor mechanical properties, due to secondary crystallization and slow nucleation rate, limit its competition with traditional plastics in industrial and biomedical applications. Thereby, many attempts have been employed to improve the material performance of toughened PHB so as to achieve greater competitiveness and sustainability. In this review, the most recent developments of PHB-based toughening materials are discussed with respect to their approaches and strategies, which includes: drawing and thermal treatment, blending with materials from natural sources and synthetic polymers, as well as forming reinforced composites with natural fibers and inorganic fillers. The alternation of PHB chemical structure to form various types of functional copolymers with enhanced materials performance is also summarized. The expanded utilization of these newly developed sophisticated PHB materials as engineering materials and the biomedical significance in different domains are also addressed.

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.