Advanced Delivery Systems Based on Lysine or Lysine Polymers

Enhancement of waterborne pathogen removal by functionalized biochar with ε-polylysine ″dynamic arms″: Potential application in ultrafiltration system

Widespread outbreaks of threatening infections caused by unknown pathogens and water transmission have spawned the development of adsorption methods for pathogen elimination. We proposed a biochar functionalization strategy involving ε-polylysine (PLL), a bio-macromolecular poly(amino acid)s with variable folding conformations, as a "pathogen gripper" on biochar. PLL was successfully bridged onto biochar via polydopamine (PDA) crosslinking. The extension of electropositive side chains within PLL enables the capture of both nanoscale viruses and micrometer-scale bacteria in water, achieving excellent removal performances. This functionalized biochar was tentatively incorporated into ultrafiltration (UF) system, to achieve effective and controllable adsorption and retention of pathogens, and to realize the transfer of pathogens from membrane surface/pore to biochar surface as well as flushing water. The biochar-amended UF systems presents complete retention (∼7 LRV) and hydraulic elution of pathogens into membrane flushing water. Improvements in removal of organics and anti-fouling capability were observed, indicating the broken trade-off in UF pathogen removal dependent on irreversible fouling. Chemical characterizations revealed adsorption mechanisms encompassing electrostatic/hydrophobic interactions, pore filling, electron transfer, chemical bonding and secondary structure transitions. Microscopic and mechanical analyses validated the mechanisms for rapid adsorption and pathogen lysis. Low-concentration alkaline solution for used biochar regeneration, facilitated the deprotonation and transformation of PLL side chain to folded structures (α-helix/β-sheet). Biochar regeneration process also promoted the effective detachment/inactivation of pathogens and protection of functional groups on biochar, corroborated by physicochemical inspection and molecular dynamics simulation. The foldability of poly(amino acid)s acting like dynamic arms, significantly contributed to pathogen capture/desorption/inactivation and biochar regeneration. This study also inspires future investigation for performances of UF systems amended by poly(amino acid)s-functionalized biochar under diverse pressure, temperature, reactive oxygen species of feeds and chemical cleaning solutions, with far-reaching implications for public health, environmental applications of biochar, and UF process improvement.

Cationic cycloamylose based nucleic acid nanocarriers

Nucleic acid delivery by viral and non-viral methods has been a cornerstone for the contemporary gene therapy aimed at correcting the defective genes, replacing of the missing genes, or downregulating the expression of anomalous genes is highly desirable for the management of various diseases. Ostensibly, it becomes paramount for the delivery vectors to intersect the biological barriers for accessing their destined site within the cellular environment. However, the lipophilic nature of biological membranes and their potential to limit the entry of large sized, charged, hydrophilic molecules thus presenting a sizeable challenge for the cellular integration of negatively charged nucleic acids. Furthermore, the susceptibility of nucleic acids towards the degrading enzymes (nucleases) in the lysosomes present in cytoplasm is another matter of concern for their cellular and nuclear delivery. Hence, there is a pressing need for the identification and development of cationic delivery systems which encapsulate the cargo nucleic acids where the charge facilitates their cellular entry by evading the membrane barriers, and the encapsulation shields them from the enzymatic attack in cytoplasm. Cycloamylose bearing a closed loop conformation presents a robust candidature in this regard owing to its remarkable encapsulating tendency towards nucleic acids including siRNA, CpG DNA, and siRNA. The presence of numerous hydroxyl groups on the cycloamylose periphery provides sites for its chemical modification for the introduction of cationic groups, including spermine, (3-Chloro-2 hydroxypropyl) trimethylammonium chloride (Q188), and diethyl aminoethane (DEAE). The resulting cationic cycloamylose possesses a remarkable transfection efficiency and provides stability to cargo oligonucleotides against endonucleases, in addition to modulating the undesirable side effects such as unwanted immune stimulation. Cycloamylose is known to interact with the cell membranes where they release certain membrane components such as phospholipids and cholesterol thereby resulting in membrane destabilization and permeabilization. Furthermore, cycloamylose derivatives also serve as formulation excipients for improving the efficiency of other gene delivery systems. This review delves into the various vector and non-vector-based gene delivery systems, their advantages, and limitations, eventually leading to the identification of cycloamylose as an ideal candidate for nucleic acid delivery. The synthesis of cationic cycloamylose is briefly discussed in each section followed by its application for specific delivery/transfection of a particular nucleic acid.

Developmental Formulation Principles of Food Preservatives by Nanoencapsulation-Fundamentals, Application, and Challenges

The role of food additives is to preserve food by extending shelf life and limiting harmful microorganism proliferation. They prevent spoilage by enhancing the taste and safety of food by utilizing beneficial microorganisms and their antimicrobial metabolites. Current advances in food preservation and processing utilize green technology principles for green preservative formulation, enhancing nutrition and supplying essential micronutrients safely, while also improving quality, packaging, and food safety. Encapsulation is gaining attention for its potential to protect delicate materials from oxidative degradation and extend their shelf life, thereby ensuring optimal nutrient uptake. Nanoencapsulation of bioactive compounds has significantly improved the food, pharmaceutical, agriculture, and nutraceutical industries by protecting antioxidants, vitamins, minerals, and essential fatty acids by controlling release and ensuring delivery to specific sites in the human body. This emerging area is crucial for future industrial production, improving the sensory properties of foods like color, taste, and texture. Research on encapsulated bioactive compounds like bacteriocins, LAB, natamycin, polylysine, and bacteriophage is crucial for their potential antioxidant and antimicrobial activities in food applications and the food industry. This paper reviews nanomaterials used as food antimicrobial carriers, including nanoemulsions, nanoliposomes, nanoparticles, and nanofibers, to protect natural food antimicrobials from degradation and improve antimicrobial activity. This review discusses nanoencapsulation techniques for biopreservative agents like nisin, poly lysine, and natamycin, focusing on biologically-derived polymeric nanofibers, nanocarriers, nanoliposomes, and polymer-stabilized metallic nanoparticles. Nanomaterials, in general, improve the dispersibility, stability, and availability of bioactive substances, and this study discusses the controlled release of nanoencapsulated biopreservative agents.

Injectable Nanocomposite Hydrogels with Strong Antibacterial, Osteoinductive, and ROS-Scavenging Capabilities for Periodontitis Treatment

Injectable antibacterial and osteoinductive hydrogels have received considerable attention for promoting bone regeneration owing to their versatile functionalities. However, a current hydrogel with antibacterial, osteoinductive, and antioxidant properties by a facile method for periodontitis treatment is still missing. To overcome this issue, we designed an injectable hydrogel system (GPM) composed of gelatin, Ti3C2Tx MXene nanosheets, and poly-l-lysine using a simple enzymatic cross-linking technique. Physicochemical characterization demonstrated that the GPM hydrogel matrix exhibited excellent stability, moderate tissue adhesion ability, and good mechanical behavior. The GPM hydrogels significantly inhibited the growth of Porphyromonas gingivalis, scavenged reactive oxygen species, attenuated inflammatory responses, and enhanced bone tissue regeneration. Intriguingly, the arrangement of the junctional epithelium, alveolar bone volume, and alveolar bone height in the GPM-treated periodontal disease group recovered to that of the healthy group. Therefore, our injectable hydrogel system with versatile functions may serve as an excellent tissue scaffold for the treatment of periodontitis.

A multifunctional composite nanoparticle with antibacterial activities, anti-inflammatory, and angiogenesis for diabetic wound healing

The treatment of chronic diabetic wounds remains challenging due to the rapid bacterial infection, severe inflammation, and insufficient angiogenesis. To address these challenges, a novel multifunctional composite nanoparticle is developed by co-assembling antisolvent-induced co-assembling silk-fibroin ε-poly-l-Lysine nanoparticles (nSF-EPL) and further assembling nSF-EPL with polydeoxyribonucleotide (PDRN) and exosome derived from human umbilical mesenchymal stem cells (Exo). Owing to the modification of EPL, PDRN and Exo, composite nanoparticles exhibited synergistic antibacterial action, anti-inflammatory and angiogenesis, which can significantly benefit for promoting wound healing. Release results show that the composite nanoparticles exhibit long-term sustained PDRN and Exo release profiles as well as outstanding release efficiency. Furthermore, in vitro studies show that the composite nanoparticles exhibit effective antibacterial activity, thus inducing an anti-inflammatory M2 macrophages phenotype and promoting angiogenesis. In vivo research results of investigations pertaining to diabetic wound healing show that the composite nanoparticles have good anti-inflammatory and angiogenesis capabilities, which can promote granulation tissue formation, collagen deposition, wound tissue epithelialization, and significantly accelerate skin healing. This study presents a promising strategy for the clinical treatment of chronic diabetic wounds.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Cationic Materials for Gene Therapy: A Look Back to the Birth and Development of 2,2-Bis-(hydroxymethyl)Propanoic Acid-Based Dendrimer Scaffolds

Gene therapy is extensively studied as a realistic and promising therapeutic approach for treating inherited and acquired diseases by repairing defective genes through introducing (transfection) the "healthy" genetic material in the diseased cells. To succeed, the proper DNA or RNA fragments need efficient vectors, and viruses are endowed with excellent transfection efficiency and have been extensively exploited. Due to several drawbacks related to their use, nonviral cationic materials, including lipidic, polymeric, and dendrimer vectors capable of electrostatically interacting with anionic phosphate groups of genetic material, represent appealing alternative options to viral carriers. Particularly, dendrimers are highly branched, nanosized synthetic polymers characterized by a globular structure, low polydispersity index, presence of internal cavities, and a large number of peripheral functional groups exploitable to bind cationic moieties. Dendrimers are successful in several biomedical applications and are currently extensively studied for nonviral gene delivery. Among dendrimers, those derived by 2,2-bis(hydroxymethyl)propanoic acid (b-HMPA), having, unlike PAMAMs, a neutral polyester-based scaffold, could be particularly good-looking due to their degradability in vivo. Here, an overview of gene therapy, its objectives and challenges, and the main cationic materials studied for transporting and delivering genetic materials have been reported. Subsequently, due to their high potential for application in vivo, we have focused on the biodegradable dendrimer scaffolds, telling the history of the birth and development of b-HMPA-derived dendrimers. Finally, thanks to a personal experience in the synthesis of b-HMPA-based dendrimers, our contribution to this field has been described. In particular, we have enriched this work by reporting about the b-HMPA-based derivatives peripherally functionalized with amino acids prepared by us in recent years, thus rendering this paper original and different from the existing reviews.

Fluorophore-Tagged Poly-Lysine RAFT Agents: Controlled Synthesis of Trackable Cell-Penetrating Peptide-Polymers

The conjugation of a fluorophore and a variety of cell-penetrating peptides onto a RAFT agent allowed for the synthesis of polymers of defined sizes with quantifiable cell-uptake. Each peptide-RAFT agent was used to polymerize acrylamide, acrylate, and styrene monomers to form high or low molecular weight polymers (here 50 or 7.5 kDa) with the peptide having no influence on the RAFT agent's control. The incorporation of a single fluorophore per polymer chain allowed cellular analysis of the uptake of the size-specific peptide-polymers via flow cytometry and confocal microscopy. The cell-penetrating peptides had a direct effect on the efficiency of polymer uptake for both high and low molecular weight polymers, demonstrating the versatility of the strategy. These "all-in-one", synthetically accessible RAFT agents allow highly controlled preparation of synthetic peptide-polymer conjugates and subsequent quantification of their delivery into cells.

Stimuli-Responsive Hydrogels for Protein Delivery

Proteins and peptides are potential therapeutic agents, but their physiochemical properties make their use as drug substances challenging. Hydrogels are hydrophilic polymeric networks that can swell and retain high amounts of water or biological fluids without being dissolved. Due to their biocompatibility, their porous structure, which enables the transport of various peptides and proteins, and their protective effect against degradation, hydrogels have gained prominence as ideal carriers for these molecules' delivery. Particularly, stimuli-responsive hydrogels exhibit physicochemical transitions in response to subtle modifications in the surrounding environment, leading to the controlled release of entrapped proteins or peptides. This review is focused on the application of these hydrogels in protein and peptide delivery, including a brief overview of therapeutic proteins and types of stimuli-responsive polymers.

Oral Delivery of Protein Drugs via Lysine Polymer-Based Nanoparticle Platforms

Oral delivery of proteins has opened a new perspective for the treatment of different diseases. However, advances of oral protein formulation are usually hindered by protein susceptibility and suboptimal absorption in the gastrointestinal tract (GIT). Polymeric nano drug delivery systems are considered revolutionary candidates to solve these issues, which can be preferably tunable against specific delivery challenges. Herein, a tailored family of lysine-based poly(ester amide)s (Lys-aaPEAs) is designed as a general oral protein delivery platform for efficient protein loading and protection from degradation. Insulin, as a model protein, can achieve effective internalization by epithelial cells and efficient transport across the intestinal epithelium layer into the systemic circulation, followed by controlled release in physiological environments. After the oral administration of insulin carried by Lys-aaPEAs with ornamental hyaluronic acid (HA), mice with type 1 diabetes mellitus showed an acceptable hypoglycemic effect with alleviated complications. A successful oral insulin delivery is associated with patient comfort and convenience and simultaneously avoids the risk of hypoglycemia compared with injections, which is of great feasibility for daily diabetes therapy. More importantly, this versatile Lys-aaPEAs polymeric library can be recognized as a universal vehicle for oral biomacromolecule delivery, providing more possibilities for treating various diseases.

One pot preparation of muti-mode nanoplatform to combat ovarian cancer

Ovarian cancer is one of the most common gynecological cancers with high mortality rate. The battle against ovarian cancer usually impaired by the evolved multidrug resistance (MDR) phenotype as well as metastasis in cancers, which urgently call for the development of multi-mode strategies to overcome the MDR and reduce metastasis. Considering the good benefits of ferroptosis and photothermal therapy (PTT) in cancer management, we herein proposed a facile way to construct nanoparticle platform (Fe-Dox/PVP) composed of ferric chloride, doxorubicin (Dox) and polyvinyl pyrrolidone (PVP) for the multi-mode therapy of ovarian cancer using chemotherapy, ferroptosis and mild hypothermia PTT. Our results demonstrated that Fe-Dox/PVP with mild hypothermia was shown to have improved endosomal escape/drug delivery, enhanced ferroptosis induction and good tumor targeting effects. Most importantly, the integration of all three effects into one platform provided increased anti-metastasis effect and promising in vitro/in vivo anticancer performance with high biocompatibility. In this study, we offer a facile and robust way to prepare a multi-mode nanoplatform to combat ovarian cancer, which can be further extended for the management of many other cancers.

Stimuli-responsive electrospun nanofibers for drug delivery, cancer therapy, wound dressing, and tissue engineering

The stimuli-responsive nanofibers prepared by electrospinning have become an ideal stimuli-responsive material due to their large specific surface area and porosity, which can respond extremely quickly to external environmental incitement. As an intelligent drug delivery platform, stimuli-responsive nanofibers can efficiently load drugs and then be stimulated by specific conditions (light, temperature, magnetic field, ultrasound, pH or ROS, etc.) to achieve slow, on-demand or targeted release, showing great potential in areas such as drug delivery, tumor therapy, wound dressing, and tissue engineering. Therefore, this paper reviews the recent trends of stimuli-responsive electrospun nanofibers as intelligent drug delivery platforms in the field of biomedicine.

Permeable polymersomes from temperature and pH dual stimuli-responsive PVCL-b-PLL block copolymers for enhanced cell internalization and lysosome targeting

A series of dual stimuli-responsive block copolymers comprising temperature-responsive poly(N-vinylcaprolactam) (PVCL) and biodegradable pH-responsive poly(l-lysine) (PLL) of varying chain length were synthesized by a combination of free radical polymerization and ring opening polymerization. The block copolymers formed micelles and vesicles (polymersomes) in response to temperature and pH, respectively, in aqueous solution. The nanoassemblies were characterized by transmission electron microscopy and dynamic light scattering techniques. Encapsulation of both hydrophobic and hydrophilic dyes in the polymersomes was shown. Doxorubicin (DOX) was loaded in the polymersomes and its controlled release in response to the two stimuli, independently and jointly, was studied. The drug was found to be released due to stimuli-induced increased permeability without disassembly of the polymersomes. A significant increase in the cellular uptake of the drug-loaded polymersomes at hyperthermia conditions was demonstrated at 41 °C and release of the drug upon localization in lysosomes was observed. Cellular internalization pathway of the polymersomes was investigated by competitive inhibition assay and a combination of endocytic pathways dominated by caveolae-mediated mechanism was found to be operative.

Effects of different conformations of polylysine on the anti-tumor efficacy of methotrexate nanoparticles

Drug delivery systems require that carrier materials have good biocompatibility, degradability, and constructability. Poly(amino acids), a substance with a distinctive secondary structure, not only have the basic features of the carrier materials but also have several reactive functional groups in the side chain, which can be employed as drug carriers to deliver anticancer drugs. The conformation of isomers of drug carriers has some influence on the preparation, morphology, and efficacy of nanoparticles. In this study, two isomers of polylysine, including ε-polylysine (ε-PL) and α-polylysine (α-PL), were used as drug carriers to entrap methotrexate (MTX) and construct nano-drug delivery systems. ε-PL/MTX nanoparticles with the morphology of helical nanorods presented a small particle size (115.0 nm), and relative high drug loading content (57.8 %). The anticancer effect of ε-PL/MTX nanoparticles was 1.3-fold and 2.6-fold stronger than that of α-PL/MTX nanoparticles in vivo and in vitro, respectively. ε-PL is an ideal drug carrier with potential clinical application prospects.

ECM-Inspired Hydrogels with ADSCs Encapsulation for Rheumatoid Arthritis Treatment

Due to their intrinsic anti-inflammatory and immunomodulatory properties, adipose-derived stem cells (ADSCs) are explored as a promising alternative in treating rheumatoid arthritis (RA). To address the poor survival and function loss of directly injected stem cells, efforts in this area are focus on the generation of efficient cell delivery vehicles. Herein, a novel extracellular matrix (ECM)-inspired injectable hydrogel for ADSCs encapsulation and RA treatment is proposed. The hydrogel with dendritic polylysine and polysaccharide components is formed through the reversible Schiff base crosslinking. It possesses self-healing capability, superior mechanical properties, minimal toxicity, and immunomodulatory ability. When encapsulated with ADSCs, the hydrogel could recover chronic inflammation by directly reversing the dominant macrophage phenotype from M1 to M2 and inhibiting the migration of fibroblast-like synoviocytes. Through a collagen-induced arthritis rat model, the tremendous therapeutic outcomes of this ADSCs-laden hydrogel, including inflammation attenuation, cartilage protection, and bone mineral density promotion are demonstrated. These results make the ECM-inspired hydrogel laden with ADSCs an ideal candidate for treating RA and other autoimmune disorders.

Amphiphilic sodium alginate-polylysine hydrogel with high antibacterial efficiency in a wide pH range

Bacterial infection is a major pathological factor leading to persistent wounds. With the aging of population, wound infection has gradually become a global health-issue. The wound site environment is complicated, and the pH changes dynamically during healing. Therefore, there is an urgent need for new antibacterial materials that can adapt to a wide pH range. To achieve this goal, we developed a thymol-oligomeric tannic acid/amphiphilic sodium alginate-polylysine hydrogel film, which exhibited excellent antibacterial efficacy in the pH range from 4 to 9, achieving the highest achievable 99.993 % (4.2 log units) and 99.62 % (2.4 log units) against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, respectively. The hydrogel films exhibited excellent cytocompatibility, suggesting that the materials are promising as a novel wound healing material without the concern of biosafety.

Entirely S-protected thiolated hydroxyethylcellulose: Design of a dual cross-linking approach for hydrogels

AIM

The aim of this study was the synthesis and evaluation of entirely S-protected thiolated hydroxyethylcellulose (HEC) with low and high viscosity, as well as thiolated poly-L-lysine (poly-L-Lys) used as dual-acting ionic as well as thiol-disulfide exchange mediated cross-linking hydrogel.

METHODS

Bis(mercaptosuccinic acid) was covalently attached to low and high viscous HECs via Fisher esterification, obtaining S-protected polymers. Poly-L-Lys-cysteine was synthesized via amidation of poly-L-Lys-HBr with cysteine (Cys). Thiolated polymers were examined in terms of cytotoxicity and rheological behavior of hydrogels containing these thiomers was evaluated with a cone-plate rheometer.

RESULTS

Thiomers showed less cytotoxicity compared to the corresponding unmodified polymers. Rheological studies showed that cross-linking occurred between the two polymers via thiol-disulfide exchange reactions facilitated by the complementary charges. Employing poly-L-Lys-Cys in a concentration of either 0.5 or 5% (m/v) resulted in a 34.5-fold or 17.3-fold as well as a 53.6-fold or 29.6-fold improvement in dynamic viscosity within 5 min at 37 °C on S-protected thiolated low and high viscous HEC, compared to the corresponding unmodified HECs, respectively.

CONCLUSION

By the combination of anionic S-protected thiolated polymers with a cationic thiolated polymer, dual-acting hydrogels exhibiting a time dependent increase in viscosity can be designed.

Design of Smart Nanodiamonds: Introducing pH Sensitivity to Improve Nucleic Acid Carrier Efficiency of Diamoplexes

The mechanism of cellular uptake and intracellular fate of nanodiamond/nucleic acid complexes (diamoplexes) are major determinants of its performance as a gene carrier. Our group designed lysine-nanodiamonds (K-NDs) as vectors for nucleic acid delivery. In this work, we modified the surface of K-NDs with histidine to overcome endo-lysosomal entrapment diamoplexes, the major rate limiting step in gene transfer. Histidine is conjugated onto the NDs in two configurations: lysyl-histidine-NDs (HK-NDs) where histidine is loaded on 100% of the lysine moieties and lysine/lysyl-histidine-NDs (H50K50-NDs) where histidine is loaded on 50% of the lysine moieties. Both HK-NDs and H50K50-NDs maintained the optimum size distribution (i.e., <200 nm) and a cationic surface (zeta potential > 20 mV), similar to K-NDs. HK-NDs binds plasmid deoxyribonucleic acid (pDNA) and small interfering ribonucleic acid (siRNA) forming diamoplexes at mass ratios of 10:1 and 60:1, respectively. H50K50-NDs significantly improved nucleic acid binding, forming diamoplexes at a 2:1 mass ratio with pDNA and a 30:1 mass ratio with siRNA, which are at values similar to the K-NDs. The amount of histidine on the surface also impacted the interactions with mammalian cells. The HK-NDs reduced the cell viability by 30% at therapeutic concentrations, while H50K50-NDs maintained more than 90% cell viability, even at the highest concentrations. H50K50-NDs also showed highest cellular uptake within 24 h, followed by K-NDs and HK-NDs. Most functionalized NDs show cellular exit after 5 days, leaving less than 10% of cells with internalized diamonds. The addition of histidine to the ND resulted in higher transfection of anti-green fluorescent protein siRNA (anti-GFP siRNA) with the fraction of GFP knockdown being 0.8 vs. 0.6 for K-NDs at a mass ratio of 50:1. H50K50-NDs further improved transfection by achieving a similar fraction of GFP knockdown (0.8) at a lower mass ratio of 30:1. Overall, this study provides evidence that the addition of histidine, a pH-modulating entity in the functionalization design at an optimized ratio, renders high efficiency to the diamoplexes. Further studies will elucidate the uptake mechanism and intracellular fate to build the relationship between physicochemical characteristics and biological efficacy and create a platform for solid-core nanoparticle-based gene delivery.

Hydrophilic Poly(glutamic acid)-Based Nanodrug Delivery System: Structural Influence and Antitumor Efficacy

Poly(amino acids) have advanced characteristics, including unique secondary structure, enzyme degradability, good biocompatibility, and stimuli responsibility, and are suitable as drug delivery nanocarriers for tumor therapy. The isoform structure of poly(amino acids) plays an important role in their antitumor efficacy and should be researched in detail. In this study, two kinds of pH-sensitive isoforms, including α-poly(glutamic acid) (α-PGA) and γ-PGA, were selected and used as nanocarriers to prepare a nanodrug delivery system. According to the preparation results, α-PGA can be used as an ideal drug carrier. Selecting doxorubicin (DOX) as the model drug, an α-PGA/DOX nanoparticle (α-PGA/DOX NPs) with a particle size of 110.4 nm was prepared, and the drug-loading content was 66.2%. α-PGA/DOX NPs presented obvious sustained and pH-dependent release characteristics. The IC₅₀ value of α-PGA/DOX NPs was 1.06 ± 0.77 μg mL⁻¹, decreasing by approximately 8.5 fold in vitro against 4T1 cells after incubation for 48 h. Moreover, α-PGA/DOX NPs enhanced antitumor efficacy in vivo, the tumor inhibition rate was 67.4%, increasing 1.5 fold over DOX injection. α-PGA/DOX NPs also reduced the systemic toxicity and cardiotoxicity of DOX. In sum, α-PGA is a biosafe nanodrug delivery carrier with potential clinical application prospects.

A Redox-Activatable and Targeted Photosensitizing Agent to Deliver Doxorubicin for Combining Chemotherapy and Photodynamic Therapy

Currently, tumors have become a serious disease threatening human health and life in modern society. Photo-chemo combination therapy is considered to be an important method to improving the efficiency of tumor treatment, especially in the treatment of multi-drug-resistant tumors. However, the application of photo-chemo combination therapy has been limited by the poor water solubility of photosensitizers, low tumor targeting, and high side effects of chemotherapy drugs. In order to solve these problems, a smart nano drug delivery platform FA-PEG-ss-PLL(-g-Ce6) designed and synthesized by us. The smart nano drug carrier uses folic acid (FA) as the targeting group, polyethylene glycol (PEG) as the hydrophilic end, Ce6-grafted polylysine (PLL(-g-Ce6)) as the hydrophobic end, and Chlorin e6 (Ce6) as the photosensitizer of photodynamic therapy, and it connects PEG to PLL by a redox-responsive cleavable disulfide linker (-ss-). Finally, the combination of tumor chemotherapy and photodynamic therapy (PDT) is realized by loading with anticancer drug doxorubicin (DOX) to the intelligent carrier. In vitro experiments showed that the drug loading content (DLC%) of DOX@FA-PEG-ss-PLL(-g-Ce6) nanoparticles (DOX@FPLC NPs) was as high as 14.83%, and the nanoparticles had good serum stability, reduction sensitivity and hemocompatibility. From the cytotoxicity assays in vitro, we found that under 664 nm laser irradiation DOX@FPLC NPs showed stronger toxicity to MCF-7 cells than did DOX, Ce6 + laser, and DOX + Ce6 + laser. Moreover, the antitumor efficiency in vivo and histopathological analysis showed that DOX@FPLC NPs under 664 nm laser irradiation exhibited higher antitumor activity and lower systemic toxicity than single chemotherapy. These results suggested that the FA-PEG-ss-PLL(-g-Ce6) nano drug delivery platform has considerable potential for the combination of chemotherapy and PDT.

A pH- and Bioreducible Cationic Copolymer with Amino Acids and Piperazines for Adenovirus Delivery

Adenoviruses (Ads) are attractive nonviral vectors and show great potential in cancer gene therapy. However, inherent properties of Ads, including immunogenicity, nonspecific toxicity, and coxsackie and adenovirus receptor (CAR)-dependent cell uptake, limit their clinical use. To surmount these issues, we developed a pH- and glutathione-responsive poly(ethylene glycol)-poly(ꞵ-aminoester)-polyethyleneimine (PPA) for conjugation with Ad. The pH sensitivity of the PPA copolymer was elegantly tuned by substitution with different amino acids (arginine, histidine, and tryptophan), piperazines (Pip1, Pip2, and Pip3), and guanidine residues in the backbone of the PPA conjugate. PPA copolymer was further functionalized with short-chain cross-linker succinimidyl 3-(2-pyridyldithio)propionate) (SPDP) to obtain PPA-SPDP for facile conjugation with Ad. The PPA-conjugated Ad (PPA-Ad) conjugate was obtained by reacting PPA-SPDP conjugate with thiolated Ad (Ad-SH). Ad-SH was prepared by reacting Ad with 2-iminothiolane. The size distribution and zeta potential results of PPA-Ad conjugate showed an increasing trend with an increase in copolymer dose. From in vitro test, it was found that the transduction efficiency of PPA-Ad conjugate in CAR-positive cells (A549 and H460 cells) was remarkably increased at the acidic pH condition (pH 6.2) when compared with PPA-Ad conjugate incubated under the physiological condition (pH 7.4). Interestingly, the increase in transduction efficiency was evidenced in CAR-negative cells (MDA-MB-231 and T24 cells). These results demonstrated that biocompatible and biodegradable PPA copolymers can efficiently cover the surface of Ad and can increase the transduction efficiency, and hence PPA copolymers can be a useful nanomaterial for viral vector delivery in cancer therapy.

Hydrogel based on nanocellulose/polydopamine/gelatin are used for the treatment of MRSA infected wound with broad-spectrum antibacterial, antioxidant property and tissue suitability

Most wound dressings have a series of problems when dealing with bacterial infection of wounds, for example, for lack of sufficient antibacterial and antioxidant capacity, comfort and mechanical properties are...