Emergence of tissue-like mechanics from fibrous networks confined by close-packed cells.

The viscoelasticity of the crosslinked semiflexible polymer networks-such as the internal cytoskeleton and the extracellular matrix-that provide shape and mechanical resistance against deformation is assumed to dominate tissue mechanics. However, the mechanical responses of soft tissues and semiflexible polymer gels differ in many respects. Tissues stiffen in compression but not in extension1-5, whereas semiflexible polymer networks soften in compression and stiffen in extension6,7. In shear deformation, semiflexible polymer gels stiffen with increasing strain, but tissues do not1-8. Here we use multiple experimental systems and a theoretical model to show that a combination of nonlinear polymer network elasticity and particle (cell) inclusions is essential to mimic tissue mechanics that cannot be reproduced by either biopolymer networks or colloidal particle systems alone. Tissue rheology emerges from an interplay between strain-stiffening polymer networks and volume-conserving cells within them. Polymer networks that soften in compression but stiffen in extension can be converted to materials that stiffen in compression but not in extension by including within the network either cells or inert particles to restrict the relaxation modes of the fibrous networks that surround them. Particle inclusions also suppress stiffening in shear deformation; when the particle volume fraction is low, they have little effect on the elasticity of the polymer networks. However, as the particles become more closely packed, the material switches from compression softening to compression stiffening. The emergence of an elastic response in these composite materials has implications for how tissue stiffness is altered in disease and can lead to cellular dysfunction9-11. Additionally, the findings could be used in the design of biomaterials with physiologically relevant mechanical properties.

Recent Advance in the Development of Singlet-Fission-Capable Polymeric Materials.

Singlet fission (SF) is a spin-allowed process in which a higher-energy singlet exciton is converted into two lower-energy triplet excitons via a triplet pair intermediate state. Implementing SF in photovoltaic devices holds the potential to exceed the Shockley-Queisser limit of conventional single-junction solar cells. Although great progress has been made in exploiting the underlying mechanism of SF over the past decades, the scope of materials capable of SF, particularly polymeric materials, remains poor. SF-capable polymer is one of the most potential candidates in the implementation of SF into devices due to their distinct superiorities in flexibility, solution processability and self-assembly behavior. Notably, recent advancements have demonstrated high-performance SF in isolated donor-acceptor (D-A) copolymer chains. This review provides an overview of recent progress in the development of SF-capable polymeric materials, with a significant focus on elucidating the mechanisms of SF in polymers and optimizing the design strategies for SF-capable polymers. Additionally, the paper discusses the challenges encountered in this field and presents future perspectives. It is expected that this comprehensive review will offer valuable insights into the design of novel SF-capable polymeric materials, further advancing the potential for SF implementation in photovoltaic devices.

High throughput miRNA sequencing and bioinformatics analysis identify the mesenchymal cell proliferation and apoptosis related miRNAs during fetal mice palate development.

BACKGROUND: Palatogenesis requires a precise spatiotemporal regulation of gene expression. Recent studies indicate that microRNAs (miRNAs) are key factors in normal palatogenesis. The present study aimed to explain the regulatory mechanisms of miRNAs during palate development. METHODS: Pregnant ICR mice were choose at embryonic day 10.5 (E10.5). Hemotoxylin and eosin (H&E) staining was used to observe the morphological changes during the development of palatal process at embryonic day (E)13.5, E14.0, E14.5, E15.0 and E15.5. The fetal palatal tissues were collected at E13.5, E14.0, E14.5 and E15.0 to explore miRNA expression and function by high throughput sequencing and bioinformatic analysis. Mfuzz cluster analysis was used to look for miRNAs related to the fetal mice palate formation. The target genes of miRNAs were predicted by miRWalk. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed base on target genes. The mesenchymal cell proliferation and apoptosis related miRNAs-genes networks were predicted and constructed using miRWalk and Cytoscape software. The expression of mesenchymal cell proliferation and apoptosis related miRNAs at the E13.5, E14.0, E14.5, and E15.0 was detected by a quantitative real-time PCR (RT-qPCR) assay. RESULTS: H&E staining found that the palatal process grows vertically along the sides of the tongue at E13.5, the position of the tongue begins to descend and the bilateral palatal processes rise above the tongue at E14.0, the palatal process grows horizontally at E14.5, there is palatal contact fusion at E15.0, and the palatal suture disappeared at E15.5. Nine clusters of miRNA expression changes were identified in the fetal mice palate formation progression, including two reducing trends, two rising trends and five disordered trends. Next, the heatmap showed the miRNA expression from Clusters 4, 6, 9, 12 in the E13.5, E14.0, E14.5 and E15.0 groups. GO functional and KEGG pathway enrichment analysis found target genes of miRNAs in clusters involved in regulation of mesenchymal phenotype and the mitogen-activated protein kinase (MAPK) signaling pathway. Next, mesenchymal phenotype related miRNA-genes networks were constructed. The heatmap showing that the mesenchymal phenotype related miRNA expression of Clusters 4, 6, 9 and 12 at E13.5, E14.0, E14.5 and E15.0. Furthermore, the mesenchymal cell proliferation and apoptosis related miRNA-gene networks were identified in Clusters 6 and 12, including mmu-miR-504-3p-Hnf1b, etc. The expression level of mesenchymal cell proliferation and apoptosis related miRNAs at the E13.5, E14.0, E14.5, and E15.0 was verified by a RT-qPCR assay. CONCLUSIONS: For the first time, we identified that clear dynamic miRNA expression during palate development. Furthermore, we demonstrated that mesenchymal cell proliferation and apoptosis related miRNAs, genes and the MAPK signaling pathway are important during fetal mice palate development.

The CNN model aided the study of the clinical value hidden in the implant images.

PURPOSE: This article aims to construct a new method to evaluate radiographic image identification results based on artificial intelligence, which can complement the limited vision of researchers when studying the effect of various factors on clinical implantation outcomes. METHODS: We constructed a convolutional neural network (CNN) model using the clinical implant radiographic images. Moreover, we used gradient-weighted class activation mapping (Grad-CAM) to obtain thermal maps to present identification differences before performing statistical analyses. Subsequently, to verify whether these differences presented by the Grad-CAM algorithm would be of value to clinical practices, we measured the bone thickness around the identified sites. Finally, we analyzed the influence of the implant type on the implantation according to the measurement results. RESULTS: The thermal maps showed that the sites with significant differences between Straumann BL and Bicon implants as identified by the CNN model were mainly the thread and neck area. (2) The heights of the mesial, distal, buccal, and lingual bone of the Bicon implant post-op were greater than those of Straumann BL (P < 0.05). (3) Between the first and second stages of surgery, the amount of bone thickness variation at the buccal and lingual sides of the Bicon implant platform was greater than that of the Straumann BL implant (P < 0.05). CONCLUSION: According to the results of this study, we found that the identified-neck-area of the Bicon implant was placed deeper than the Straumann BL implant, and there was more bone resorption on the buccal and lingual sides at the Bicon implant platform between the first and second stages of surgery. In summary, this study proves that using the CNN classification model can identify differences that complement our limited vision.

Smart pH-Sensitive Hydrogel Based on the Pineapple Peel-Oxidized Hydroxyethyl Cellulose and the Hericium erinaceus Residue Carboxymethyl Chitosan for Use in Drug Delivery.

Pineapple and hericium erinaceus (HE) produce a lot of residues in the process of food processing. These processed residues are good potential derivative precursors. In this investigation, a simple and non-toxic method was developed to prepare one new composite hydrogel by the Schiff base reaction between the aldehyde group of oxidized hydroxyethyl cellulose (OHEC) from processed pineapple peel residue and the amino group of carboxymethyl chitosan (CMCS) from processed HE residue. Subsequently, a series of experiments toward these new hydrogel polymers including structure characterization and performances were applied. The resultant hydrogel polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy and confirmed with thermogravimetry. It was observed that the modification of cellulose and chitin was adequate, and the synthesis of OHEC/CMCS hydrogel polymers was successful. The gelation time experiments indicated that the shortest gel time was 33 s at a mass ratio of 4:6 (OHEC-70:CMCS). The hydrogel showed good swelling properties. The maximum swelling rate reached 11.58 g/g, and the swelling rate decreased with the increase of the oxidation degree of OHEC. The drug delivery applications of the prepared hydrogel were evaluated with bovine serum albumin (BSA) as a model drug releasing in vitro. It was discovered that the BSA release from the hydrogel was pH sensitive under simulated gastrointestinal conditions. All of these attributes indicate that the novel prepared hydrogel polymers have the potential as good carriers for oral delivery of protein-type drugs.

Tetrahedral Framework Nucleic Acids Deliver Antimicrobial Peptides with Improved Effects and Less Susceptibility to Bacterial Degradation.

Antimicrobial peptides (AMPs) have been an attractive alternative to traditional antibiotics. However, considerable efforts are needed to further enhance their antimicrobial effects and stability against bacterial degradation. Tetrahedral framework nucleic acids (tFNAs), a new class of three-dimensional nanostructures, have been utilized as a delivery vehicle. In this study, tFNAs were combined for the first time with an antimicrobial peptide GL13K, and the effects of the resultant complexes against Escherichia coli (sensitive to GL13K) and Porphyromonas gingivalis (capable of degrading GL13K) were investigated. tFNA-based delivery enhanced the effects of GL13K against E. coli. The tFNA vehicle both increased bacterial uptake and promoted membrane destabilization. Moreover, it enhanced the effects of GL13K against P. gingivalis by protecting the peptide against degradation in the protease-rich extracellular environment. Therefore, tFNA provides a delivery vehicle for AMPs targeting a broad range of disease.

Zwitterionic PMCP-Modified Polycaprolactone Surface for Tissue Engineering: Antifouling, Cell Adhesion Promotion, and Osteogenic Differentiation Properties.

Biodegradable polycaprolactone (PCL) has been widely applied as a scaffold material in tissue engineering. However, the PCL surface is hydrophobic and adsorbs nonspecific proteins. Some traditional antifouling modifications using hydrophilic moieties have been successful but inhibit cell adhesion, which is not ideal for tissue engineering. The PCL surface is modified with bioinspired zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (PMCP) via surface-initiated atom transfer radical polymerization to improve cell adhesion through the unique interaction between choline phosphate (CP, on PMCP) and phosphate choline (PC, on cell membranes). The hydrophilicity of the PCL surface is significantly enhanced after surface modification. The PCL-PMCP surface reduces nonspecific protein adsorption (e.g., up to 91.7% for bovine serum albumin) due to the zwitterionic property of PMCP. The adhesion and proliferation of bone marrow mesenchymal stem cells on the modified surface is remarkably improved, and osteogenic differentiation signs are detected, even without adding any osteogenesis-inducing supplements. Moreover, the PCL-PMCP films are more stable at the early stage of degradation. Therefore, the PMCP-functionalized PCL surface promotes cell adhesion and osteogenic differentiation, with an antifouling background, and exhibits great potential in tissue engineering.

Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

Radiofrequency-responsive black phosphorus nanogel crosslinked with cisplatin for precise synergy in multi-modal tumor therapies.

Radiofrequency-responsive nanoparticles (RFNPs) have drawn increasingly attentions as RF energy absorbing antenna to enhance antitumor efficacy of radiofrequency ablation (RFA). However, it remains a huge challenge for inorganic RFNPs to precisely synergize RFA with other antitumor modes in a clinically acceptable way on bio-safety and bio-compatibility. In this work, RF-responsive black phosphorus (BP) nanogel (BP-Pt@PNA) was successfully fabricated by crosslinking coordination of cisplatin with BP and temperature sensitive polymer PNA. BP-Pt@PNA exhibited strong RF-heating effect and RF-induced pulsatile release of cisplatin. Under RF irradiation, BP-Pt@PNA exhibited cytotoxic enhancement on 4T1 cells. By the synergistic effect of BP and cisplatin, BP-Pt@PNA achieved RF-stimulated systemic immune effect, thus induced enhance suppression on tumor growth and metastasis. Moreover, BP-Pt@PNA realized long-term drug retention in tumor and favorable embolization to tumor-feeding arteries. With high drug loading capacity and favorable bio-safety and bio-degradability, BP-Pt@PNA is expected as an ideal RFNP for precisely synergizing RFA with other antitumor modes in clinical application.

Characterization of Chitosan-Gallic Acid Graft Copolymer for Periodontal Dressing Hydrogel Application.

The postoperative periodontal wound is in a complex physiological environment; the bacteria accumulation, the saliva stimulation, and the food residues retention will aggravate the wound deterioration. Commercial periodontal dressings have been widely used for postoperative periodontal treatment, and there still exists some problems, such as poor biocompatibility, weak adhesion, insufficient antibacterial, and anti-inflammatory properties. In this study, a chitosan-gallic acid graft copolymer (CS-GA) is synthesized as a potential periodontal dressing hydrogel. CS-GA possesses high swelling rate, adjustable degradability, self-healing ability, biocompatibility, strong adhesion ability, high mechanical properties and toughness. Furthermore, CS-GA has good scavenging ability for ·OH, O2 - , and 1 O2. And CS-GA has good inhibition effect on different bacterial through bacterial membranes damage. CS-GA can stop bleeding in a short time and adsorb erythrocytes to form physical blood clots to enhance the hemostatic performance. In addition, CS-GA can reduce inflammatory factors expressions, increase collagen fibers deposition, and neovascularization to promote wounds healing, which makes it as a potential periodontal dressing for postoperative tissue restoration.

Thermoresponsive hydrogels from phosphorylated ABA triblock copolymers: a potential scaffold for bone tissue engineering.

A series of thermoresponsive and biocompatible ABA triblock copolymers in which the outer A blocks comprise poly(N-isopropylacrylamide) and the central B block consists of O-phosphoethanolamine (PEA) grafted poly(acrylic acid) (PAA(PEA)) are achieved by atom transfer radical polymerization (ATRP) and subsequent modification. At a relatively low concentration (2 w/v% in phosphate buffered saline), the triblock copolymers can form free-standing gels at 37 °C. Using a combination of variable-temperature 1H NMR, dynamic light scattering, and rheological measurements, it is demonstrated that the gelation behavior is highly dependent on both the length of A blocks and the substitution degree of phosphate group. To examine the potential application as scaffold for bone tissue engineering, the physical gels are incubated in the simulated body fluid (SBF) for 2 weeks. Obvious nucleation and growth of hydroxyapatite are found in the gels, as indicated by the scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction measurements. The triblock copolymers also exhibit low cytotoxicity in cell viability test. Thus the triblock copolymers have great potential for bone tissue engineering.

Durable cellulose paper by grafting thiol groups and controlling silver deposition for ultrahigh electromagnetic interference shielding.

Electromagnetic interference (EMI) shielding paper with durability and high effectiveness is of significant importance to long-term service for preventing EMI pollution. Herein, we report a practical method for preparing cellulose paper/Ag composite with outstanding durable and ultrahigh EMI shielding performance by electroless silver plating. The silver deposition process, the surface morphology, the silver content and conductivity of the composite can be controlled by varying the amount of N-acetyl-L-cysteine (NAC) grafted onto the cellulose fibers and ammonia amount for silver-ammonia complex formation. Moreover, the grafted NAC with thiol groups on cellulose can enhance the adhesion between silver and cellulose paper, meanwhile, NAC as the reducing agent can result in a more complete flower-shaped silver structure and reducing the reflection of electromagnetic waves in silver layer. The composite exhibited excellent conductivity, EMI shielding effectiveness (SE) up to 106 dB and outstanding durability. After 10,000 bending times and 60 abrasion cycles respectively, the electrical resistance of the composite only increased from 0.030 Ω/sq. to 0.041 Ω/sq. and 0.050 Ω/sq., and the EMI SE decreased to 102 dB and 105 dB.

Wound-Healing Material with Antibacterial and Antioxidant Functions, Constructed Using Keratin, Hyperbranched Polymers, and MnO2.

Wound healing, a global medical issue, poses a substantial financial burden. Therefore, developing low-cost and highly efficacious wound-healing materials is essential. In this study, we prepared keratin-hyperbranched polymer hydrogel-M (KHBP-M), a multifunctional composite gel, by mixing reduced keratin containing free sulfhydryl groups extracted from human hair waste, hyperbranched polymer (HBP) with double bonds at the end, and MnO2 nanoparticles prepared using the biological template method. Keratin has intrinsic wound-healing properties, and MnO2 is a wound-healing material with both photothermal antibacterial and reactive oxygen species (ROS)-scavenging abilities. KHBP-M showed antibacterial effects against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. When exposed to irradiation (808 nm), the killing ratio for S. aureus reached 99.99%, which is especially suitable for wound environments. A similar trend was noted for E. coli. The composite hydrogel also showed excellent ROS-scavenging ability and could resist oxidative stress in L929 cells. Furthermore, in an animal model of infected wounds, the KHBP-M hydrogel treated with near-infrared light had the fastest wound-healing rate, reaching 82.98% on day 15. Our study provides a promising wound-healing material, with simple preparation methods, easy access to sources, and low cost involved.

Hexapeptide decorated ß-cyclodextrin delivery system for targeted therapy of bone infection.

Successfully treating bone infections is a major orthopedic challenge. Clinically, oral, intravenous, or intramuscular injections of drugs are usually used for direct or complementary treatment. However, once the drug enters the system, it circulates throughout the body, leading to an insufficient local dose and limiting the therapeutic effect because of the lack of targeting in the drug system. In this study, ß-cyclodextrin, modified with poly (ethylene glycol) [PEG] and aspartic acid hexapeptide (Asp6-ß-CD), was used to specifically target the hydroxyapatite (HA) component of the bone. It was then loaded with norfloxacin (NFX) to treat bone infections. The antibacterial ability of NFX was enhanced by loading it into Asp6-ß-CD, because the solubility of Asp6-ß-CD@NFX increased significantly. Moreover, Asp6-ß-CD could target bone tissue in nude mice and showed significantly enhanced accumulation (10 times) than the unmodified ß-CD. In addition, in a rat model of osteomyelitis, Asp6-ß-CD@NFX targeted HA well and exerted its antibacterial activity, which reduced inflammation and promoted bone tissue repair. This study indicates that the Asp6-ß-CD based drug delivery system can efficiently target bone tissue to enable potential applications for treating bone-related diseases.

Multifunctional Biomedical Materials Derived from Biological Membranes.

The delicate structure and fantastic functions of biological membranes are the successful evolutionary results of a long-term natural selection process. Their excellent biocompatibility and biofunctionality are widely utilized to construct multifunctional biomedical materials mainly by directly camouflaging materials with single or mixed biological membranes, decorating or incorporating materials with membrane-derived vesicles (e.g., exosomes), and designing multifunctional materials with the structure/functions of biological membranes. Here, the structure-function relationship of some important biological membranes and biomimetic membranes are discussed, such as various cell membranes, extracellular vesicles, and membranes from bacteria and organelles. Selected literature examples of multifunctional biomaterials derived from biological membranes for biomedical applications, such as drug- and gene-delivery systems, tissue-repair scaffolds, bioimaging, biosensors, and biological detection, are also highlighted. These designed materials show excellent properties, such as long circulation time, disease-targeted therapy, excellent biocompatibility, and selective recognition. Finally, perspectives and challenges associated with the clinical applications of biological-membrane-derived materials are discussed.

A self-healing hydrogel based on oxidized microcrystalline cellulose and carboxymethyl chitosan as wound dressing material.

As the food processing by-products, hericium erinaceus residues (HER) and pineapple peel (PP) are good sources of cellulose and chitosan that can be prepared into hydrogels for structuring a drug delivery system. Hydrogel is one new type biomaterial for drug delivery with excellent absorbent ability applied in wound dressing. In this research, one composite self-healing hydrogel with pH sensitivity for drug delivery system based on the Schiff-base reaction was fabricated. Therein aldehyde group of oxidized microcrystalline cellulose (OMCC) from PP were crosslinked with amino group of carboxymethyl chitosan (CMCS) from HER via Schiff-base reaction for structuring hydrogels. The structures of the prepared hydrogels were characterized. Meanwhile, its blood clotting activity and physical properties were investigated. The hydrogels show some favorable performances with suitable gel time (54 s of minimum), distinguish swelling rate (about 31.18 g/g), good mechanical, self-healing characteristic and well coagulation effect. The cumulative release of the rutin-loaded hydrogel OMCM-54 reached about 80 % within 6 h, suggesting the well-controlled release of rutin by crosslinking degree between the modified OMCC and CMCS based on Schiff-base reaction. The novel biomaterial based on hericium erinaceus residues and pineapple peel shows its potential use as wound dressing.

Polylactic acid film surface functionalized by zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] with improved biocompatibility.

Polylactic acid (PLA) is a non-toxic, biodegradable biological material that is widely used in tissue engineering and regenerative medicine. PLA is easy to adsorb non-specific proteins and lacks cell adhesion after implantation. Choline phosphate (CP) is a novel zwitterion with a reverse structure of phosphate choline (PC) on the cell membrane that can form a specific "CP-PC" interaction to promote cell adhesion. In our previous work, modification of choline phosphate polymers (PMCP) onto the PLA film surface improved the hydrophilicity and degradation properties. In this study, we further investigated the biocompatibility of PLA-PMCP films from protein adsorption, cell adhesion and proliferation, bacterial adhesion, blood compatibility, and inflammation in vivo. The PLA-PMCP surface can resist protein adsorption and bacterial adhesion due to the anti-fouling properties of the zwitterion PMCP. Meanwhile, the PLA-PMCP surface promotes the adhesion and proliferation of BMSCs due to the specific "CP-PC" effect. In addition, the PLA-PMCP film has good blood compatibility as well as the PLA film. During in vivo experiments, biocompatibility was improved and the inflammatory response and immune rejection of PLA-PMCP films were reduced compared to those of the original PLA film. Therefore, the PMCP-modified PLA film resists protein adsorption and bacterial adhesion, promotes cell adhesion and proliferation, and has good hemocompatibility and histocompatibility. This brings a significant potential for application in the fields of tissue engineering and regenerative medicine.

A review on recovery of extracellular biopolymers from flocculent and granular activated sludges: Cognition, key influencing factors, applications, and challenges.

A reasonable recovery of excess sludge may shift the waste into wealth. Recently an increasing attention has been paid to the recycling of extracellular biopolymers from conventional and advanced biological wastewater treatment systems such as flocculent activated sludge (AS), bacterial aerobic granular sludge (AGS), and algal-bacterial AGS processes. This review provides the first overview of current research developments and future directions in the recovery and utilization of high value-added biopolymers from the three types of sludge. It details the discussion on the recent evolvement of cognition or updated knowledge on functional extracellular biopolymers, as well as a comprehensive summary of the operating conditions and wastewater parameters influencing the yield, quality, and functionality of alginate-like exopolymer (ALE). In addition, recent attempts for potential practical applications of extracellular biopolymers are discussed, suggesting research priorities for overcoming identification challenges and future prospects.

Zwitterionic choline phosphate conjugated folate-poly (ethylene glycol): a general decoration of erythrocyte membrane-coated nanoparticles for enhanced tumor-targeting drug delivery.

Erythrocyte membrane nanosystems have become one of the important research directions of disease treatment, especially for tumor treatment, and can enhance the long circulation time of anti-cancer drugs in vivo, and penetrate and accumulate in the tumor site effectively. However, erythrocyte membranes lack targeting properties and it is necessary to provide tumor-targeting function by modifying erythrocyte membranes. In this study, we report on a novel modification method of an erythrocyte membrane nanosystem to target tumors. Specifically, the tumor-targeting molecule folate-poly (ethylene glycol) (FA-PEG) was modified with a zwitterionic 2-(methyl acryloyoxy) ethyl choline phosphate (MCP) by the Michael addition reaction to obtain MCP-modified FA-PEG (MCP-PEG-FA). Based on the strong "N-P" tetravalent electrostatic interaction between MCP and phosphatidyl choline on the erythrocyte membranes, MCP-PEG-FA can be modified on the erythrocyte membrane encapsulated doxorubicin (DOX) loaded poly(lactic-co-glycolic acid) (PLGA) nanosystem to form a tumor-targeting erythrocyte membrane nanosystem (FA-RBC@PLGA-DOX). The results show that MCP-PEG-FA was synthesized and successfully bonded to the erythrocyte membrane nanosystem, and the FA-RBC@PLGA-DOX nanosystem had a better tumor-targeting function and tumor killing effect compared with those of the nanosystems without FA ligand modification. The universal modification method of erythrocyte membranes is successfully provided and can be applied to the treatment of various diseases.

Near-Infrared Light-Controllable Multifunction Mesoporous Polydopamine Nanocomposites for Promoting Infected Wound Healing.

The successful treatment of infected wounds requires strategies with effective antimicrobial, anti-inflammatory, and healing-promoting properties. Accordingly, the use of Cu2+ and tetracycline (TC), which can promote angiogenesis, re-epithelialization, and collagen deposition, also antibacterial activity, at the wound site, has shown application prospects in promoting infected wound repair. However, realizing controllable release to prolong action time and avoid potential toxicities is critical. Moreover, near-infrared light (NIR)-activated mesoporous polydopamine nanoparticles (MPDA NPs) reportedly exert anti-inflammatory effects by eliminating the reactive oxygen species generated during inflammatory responses. In this study, we assess whether Cu2+ and TC loaded in MPDA NPs can accelerate infected wound healing in mice. In particular, Cu2+ is chelated and immobilized on the surface of MPDA NPs, while a thermosensitive phase-change material (PCM; melting point: 39-40 °C), combined with antibiotics, was loaded into the MPDA NPs as a gatekeeper (PPMD@Cu/TC). Results show that PPMD@Cu/TC exhibits significant great photothermal properties with NIR irradiation, which induces the release of Cu2+, while inducing PCM melting and, subsequent, TC release. In combination with anti-inflammatory therapy, NIR-triggered Cu2+ and TC release enables the nanocomposite to eradicate bacterial wound infections and accelerate healing. Importantly, negligible damage to primary organs and satisfactory biocompatibility were observed in the murine model. Collectively, these findings highlight the therapeutic potential of this MPDA-based platform for controlling bacterial infection and accelerating wound healing.