Formulation of pH-responsive PEGylated nanoparticles with high drug loading capacity and programmable drug release for enhanced antibacterial activity

Radical-Scavenging Violet Phosphorus Nanosheets for Attenuating Hyperinflammation and Promoting Infected Wound Healing

Antibacterial therapy targeting the regulation of macrophage polarization may be a useful approach for normalizing the immune environment and accelerating wound healing. Inspired by black phosphorus-based nanoplatforms, more stable yet less-explored violet phosphorus nanosheets (VPNSs) are expected to provide a superior solution for effectively combating bacterial infections. In this study, an average thickness of 5-7 nm VPNSs are fabricated through the liquid-phase exfoliation method to serve as an immunoregulatory dressing for the treatment of infected wounds. VPNSs attenuated excessive reactive oxygen species (ROS) and reduced the accumulation of proinflammatory M1 macrophages, showing notable antioxidant and anti-inflammatory properties. Comprehensive RNA sequencing further elucidated the potential immunoregulatory mechanisms of VPNSs, including modulation of the inflammatory response and enzyme regulator activity. Additionally, the inherent photothermal properties of the VPNSs contributed significantly to their antibacterial efficacy. When combined with near-infrared laser irradiation, VPNSs showed remarkable effectiveness in reducing infection-related complications and expediting wound healing in infected skin wound models. The rapid promotion of wound healing through ROS clearance, the regulation of macrophage polarization, and hyperthermia generation underscores the potential of the violet-phosphorus-based nanoplatforms as clinically viable agents for treating infected wounds. This study suggests that VPNSs are promising candidates for clinical anti-infective and anti-inflammatory applications.

Recent Advances in Self-Assembling Peptide-Based Nanomaterials for Enhanced Photodynamic Therapy

Self-assembling peptide-based materials with ordered nanostructures possess advantages such as good biocompatibility and biodegradability, superior controllability, and ease of chemical modification. Through covalent conjugation or non-covalent encapsulation, photosensitizers (PSs) can be carried by self-assembling peptide-based nanomaterials for targeted delivery towards tumor tissues. This improves the stability, solubility, and tumor accumulation of PSs, as well as reduces their dark toxicity. More importantly, these nanomaterials can be tailored with responsiveness to tumor microenvironment, which enables smart release of PSs for precise and enhanced photodynamic therapy (PDT). In this review, the self-assembly of peptide from the perspective of driving forces is first described, and various self-assembling peptide materials with zero to 3D nanostructures are subsequently highlighted for PDT of cancers in recent years. Finally, an outlook in this field is provided to motivate fabrication of advanced PDT nanomaterials.

An Integrated All-Natural Conductive Supramolecular Hydrogel Wearable Biosensor with Enhanced Biocompatibility and Antibacterial Properties

Conductive hydrogels exhibit tremendous potential for wearable bioelectronics, biosensing, and health monitoring applications, yet concurrently enhancing their biocompatibility and antimicrobial properties remains a long-standing challenge. Herein, we report an all-natural conductive supramolecular hydrogel (GT5-DACD2-B) prepared via the Schiff base reaction between the biofriendly dialdehyde cyclodextrin and gelatin. The potent antibacterial agent fusidic acid (FA) is incorporated through host-guest inclusion, enabling 100% inhibition of Staphylococcus aureus proliferation. The biocompatibility of our hydrogel is bolstered with tannic acid (TA) facilitating antibacterial effects through interactions with gelatin, while borax augments conductivity. This supramolecular hydrogel not only exhibits stable conductivity and rapid response characteristics but also functions as a flexible sensor for monitoring human movement, facial expressions, and speech recognition. Innovatively integrating biocompatibility, antimicrobial activity, and conductivity into a single system, our work pioneers a paradigm for developing multifunctional biosensors with integrated antibacterial functionalities, paving the way for advanced wearable bioelectronics with enhanced safety and multifunctionality.

An Imine-Functionalized Silicone-Based Epoxy Coating with Stable Adhesion and Controllable Degradation for Enhanced Marine Antifouling and Anticorrosion Properties

Biofouling and corrosion of submerged equipment caused by marine organisms severely restrict the rapid development of the marine industry. Traditional antifouling or anticorrosion coatings typically serve a sole purpose and exhibit limited degradability upon failure, rendering them inadequate for current demands. Herein, a novel imine-functionalized command-degradable bio-based epoxy coating (SAHPEP-DDM) with enhanced integrated antifouling and anticorrosion performances was synthesized utilizing 1,3-bis (3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and syringaldehyde. Compared with commercial epoxy resins (E51-DDM) and polydimethylsiloxanes (PDMS), the SAHPEP-DDM coating exhibits superior antifouling and anticorrosion properties due to the existence of -C=N- and Si-O-Si chain segments in the cross-linking network. The coating achieves resistance rates of 99.59 % and 99.20 % against E. coli and S. aureus, respectively, and shows promising resistance against algae and proteins, as well as excellent corrosion resistance in artificial seawater (with |Z|0.01 Hz and arc radius of about 1011 Ω and exceeding 1010 Ω respectively). The coating also exhibits excellent chemical resistance in organic solvents as well as neutral and alkaline environments. Moreover, its controlled degradation after coating failure can be achieved in acid aqueous solutions through temperature and acidity adjustments, facilitated by the presence of -C=N-. This work presents a novel degradable coating successfully coupled the dual functions of antifouling and anticorrosion coatings, avoiding the employment of intermediate coat, indicating vast potential for application in various marine engineering fields.

Recent advances in nanostructured delivery systems for vancomycin

Despite the development of new generations of antibiotics, vancomycin remained as a high-efficacy antibiotic for treating the infections caused by MRSA. Researchers have explored various nanoformulations, aiming to enhance the therapeutic efficacy of vancomycin. Such novel formulations improve the effectiveness of drug cargoes in treating bacterial infections and minimizing the risk of adverse effects. The vast of researches have focuses on enhancing the permeation ability of vancomycin through different biological barriers especially those of gastrointestinal tract. Increasing the drug loading and tuning the drug release from nanocarrier are other important goal for many conducted studies. This study reviews the newest nano-based formulations for vancomycin as a key antibiotic in treating hospitalized bacterial infections.

Antibacterial Prodrugs to Overcome Bacterial Antimicrobial Resistance

Antimicrobial resistance (AMR) is an increasingly concerning phenomenon that requires urgent attention because it poses a threat to human and animal health. Bacteria undergo continuous evolution, acquiring novel resistance mechanisms in addition to their intrinsic ones. Multidrug-resistant and extensively drug-resistant bacterial strains are rapidly emerging, and it is expected that bacterial AMR will claim the lives of 10 million people annually by 2050. Consequently, the urgent need for the development of new therapeutic agents with new modes of action is evident. The antibacterial prodrug approach, a strategy that includes drug repurposing and derivatization, integration of nanotechnology, and exploration of natural products, is highlighted in this review. Thus, this publication aims at compiling the most pertinent research in the field, spanning from 2021 to 2023, offering the reader a comprehensive insight into the AMR phenomenon and new strategies to overcome it.

Biodynamer Nano-Complexes and -Emulsions for Peptide and Protein Drug Delivery

Background

Therapeutic proteins and peptides offer great advantages compared to traditional synthetic molecular drugs. However, stable protein loading and precise control of protein release pose significant challenges due to the extensive range of physicochemical properties inherent to proteins. The development of a comprehensive protein delivery strategy becomes imperative accounting for the diverse nature of therapeutic proteins.

Methods

Biodynamers are amphiphilic proteoid dynamic polymers consisting of amino acid derivatives connected through pH-responsive dynamic covalent chemistry. Taking advantage of the amphiphilic nature of the biodynamers, PNCs and DEs were possible to be prepared and investigated to compare the delivery efficiency in drug loading, stability, and cell uptake.

Results

As a result, the optimized PNCs showed 3-fold encapsulation (<90%) and 5-fold loading capacity (30%) compared to DE-NPs. PNCs enhanced the delivery efficiency into the cells but aggregated easily on the cell membrane due to the limited stability. Although DE-NPs were limited in loading capacity compared to PNCs, they exhibit superior adaptability in stability and capacity for delivering a wider range of proteins compared to PNCs.

Conclusion

Our study highlights the potential of formulating both PNCs and DE-NPs using the same biodynamers, providing a comparative view on protein delivery efficacy using formulation methods.

pH-Responsive Co-Assembled Peptide Hydrogel to Inhibit Drug-Resistant Bacterial Infection and Promote Wound Healing

Drug-resistant bacterial infection and biofilm formation are the key inhibitors of wound healing, and new strategies are urgently needed to address these issues. In this study, we designed a pH-responsive co-assembled peptide hydrogel to inhibit Methicillin-resistant Staphylococcus aureus (MRSA) infection and promote wound healing. We synthesized a cationic short peptide (Nap-FFKKK) and a co-assembled hydrogel with curcumin at pH ∼ 7.8. The loaded curcumin was continuously released in a weak acid environment (pH ∼ 5.5). The lysine-rich cationic peptide inhibited biofilm formation in MRSA via electrostatic interaction with the negatively charged bacterial cell surface and, thus, provided a reinforcing antibacterial effect with curcumin. In vitro antibacterial experiments showed that the co-assembled system considerably reduced the minimum inhibitory concentration of curcumin against MRSA by 10-fold and promoted wound healing in a mouse model of MRSA-infected wounds. This study provides a simple and promising strategy to treat drug-resistant bacterial infections in wounds.

Nanomaterials Regulate Bacterial Quorum Sensing: Applications, Mechanisms, and Optimization Strategies

Anti-virulence therapy that interferes with bacterial communication, known as "quorum sensing (QS)", is a promising strategy for circumventing bacterial resistance. Using nanomaterials to regulate bacterial QS in anti-virulence therapy has attracted much attention, which is mainly attributed to unique physicochemical properties and excellent designability of nanomaterials. However, bacterial QS is a dynamic and multistep process, and there are significant differences in the specific regulatory mechanisms and related influencing factors of nanomaterials in different steps of the QS process. An in-depth understanding of the specific regulatory mechanisms and related influencing factors of nanomaterials in each step can significantly optimize QS regulatory activity and enhance the development of novel nanomaterials with better comprehensive performance. Therefore, this review focuses on the mechanisms by which nanomaterials regulate bacterial QS in the signal supply (including signal synthesis, secretion, and accumulation) and signal transduction cascade (including signal perception and response) processes. Moreover, based on the two key influencing factors (i.e., the nanomaterial itself and the environment), optimization strategies to enhance the QS regulatory activity are comprehensively summarized. Collectively, applying nanomaterials to regulate bacterial QS is a promising strategy for anti-virulence therapy. This review provides reference and inspiration for further research on the anti-virulence application of nanomaterials.

In vitro influence of PEG functionalized ZnO-CuO nanocomposites on bacterial growth

Polyethyleneglycol-coated biocompatible CuO-ZnO nanocomposites were fabricated hydrothermally varying Zn:Cu ratios as 1:1, 2:1, and 1:2, and their antibacterial activity was determined through the well diffusion method against the Gram-negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentration and the minimum bactericidal concentration values of the synthesized samples were determined. Subsequently, the time synergy kill assay was performed to elucidate the nature of the overall inhibitory effect against the aforementioned bacterial species. The mean zone of inhibition values for all four samples are presented. The inhibitory effect increased with increasing concentration of the nanocomposite (20, 40 and 60 mg/ml) on all the bacterial species except for S. aureus. According to the MBC/MIC ratio, ZnO was found to be bacteriostatic for E. coli and P. aeruginosa, and bactericidal for S. aureus and K. pneumoniae. Zn:Cu 2:1 was bactericidal on all bacterial species. A bacteriostatic effect was observed on E. coli and P. aeruginosa in the presence of Zn:Cu 1:1 whereas, it showed a bactericidal effect on S. aureus and K. pneumoniae. Zn:Cu 1:2 exhibited a bacteriostatic effect on E. coli while a bactericidal effect was observed for E. coli, P. aeruginosa, and K. pneumoniae. The metal oxide nanocomposites were found to be more sensitive towards the Gram-positive strain than the Gram-negative strains. Further, all the nanocomposites possess anti-oxidant activity as shown by the DPPH assay.

[Preparation of berberine-naringin dual drug-loaded composite microspheres and evaluation of their antibacterial-osteogenic properties]

Objective

To develop a drug-loaded composite microsphere that can simultaneously release the berberine (BBR) and naringin (NG) to repair infectious bone defects.

Methods

The NG was loaded on mesoporous microspheres (MBG) to obtain the drug-loaded microspheres (NG-MBG). Then the dual drug-loaded compound microspheres (NG-MBG@PDA-BBR) were obtained by wrapping NG-MBG with polydopamine (PDA) and modifying the coated PDA with BBR. The composite microspheres were characterized by scanning electron microscopy, X-ray diffraction, specific surface area and pore volume analyzer, and Fourier transform infrared spectroscopy; the drug loading rate and release of NG and BBR were measured; the colony number was counted and the bacterial inhibition rate was calculated after co-culture with Staphylococcus aureus and Escherichia coli for 12 hours to observe the antibacterial effect; the biocompatibility was evaluated by live/dead cell fluorescence staining and cell counting kit 8 assay after co-culture with rat's BMSCs for 24 and 72 hours, respectively, and the osteogenic property was evaluated by alkaline phosphatase (ALP) staining and alizarin red staining after 7 and 14 days, respectively.

Results

NG-MBG@PDA-BBR and three control microspheres (MBG, MBG@PDA, and NG-MBG@PDA) were successfully constructed. Scanning electron microscopy showed that NG-MBG@PDA-BBR had a rough lamellar structure, while MBG had a smooth surface, and MBG@PDA and NG-MBG@PDA had a wrapped agglomeration structure. Specific surface area analysis showed that MBG had a mesoporous structure and had drug-loading potential. Low angle X-ray diffraction showed that NG was successfully loaded on MBG. The X-ray diffraction pattern contrast showed that all groups of microspheres were amorphous. Fourier transform infrared spectroscopy showed that NG and BBR peaks existed in NG-MBG@PDA-BBR. NG-MBG@PDA-BBR had good sustained drug release ability, and NG and BBR had early burst release and late sustained release. NG-MBG@PDA-BBR could inhibit the growth of Staphylococcus aureus and Escherichia coli, and the antibacterial ability was significantly higher than that of MBG, MBG@PDA, and NG-MBG@PDA ( P<0.05). But there was a significant difference in biocompatibility at 72 hours among microspheres ( P<0.05). ALP and alizarin red staining showed that the ALP positive area and the number of calcium nodules in NG-MBG@PDA-BBR were significantly higher than those of MBG and NG-MBG ( P<0.05), and there was no significant difference between NG-MBG@PDA and NG-MBG@PDA ( P>0.05).

Conclusion

NG-MBG@PDA-BBR have sustained release effects on NG and BBR, indicating that it has ideal dual performance of osteogenesis and antibacterial property.

A Versatile Hydrogel with Antibacterial and Sequential Drug-Releasing Capability for the Programmable Healing of Infectious Keratitis

Hydrogels have attracted tremendous attention as favorable corneal substitutes for treating severe infectious keratitis (IK). However, current hydrogel-based corneal substitutes were majorly designed to promote the single stage of corneal regeneration, which falls short in meeting the clinical management needs of severe IK including the multiple phases of corneal wound healing. Herein, we introduce a versatile hybrid hydrogel (SQPV) composed of silk fibroin and chitosan, which exhibits spatiotemporal properties for drug release. The SQPV is fabricated by incorporating verteporfin-loaded poly(lactic-co-glycolic)-polyethylene glycol-o-nitrobenzene micelles into a hydrogel network, which is formed from methacrylate silk fibroin and glycidyl methacrylate functionalized quaternized chitosan containing polydeoxyribonucleotide. This double network approach results in a material with exceptional anti-inflammatory, antibacterial, and proliferative stimulation and tissue remodeling regulation capabilities. Furthermore, SQPV showcases mechanical strength and transparency akin to those of native cornea. Extensive in vitro and in vivo studies validate SQPV's ability to effectively eliminate residual bacteria, mitigate inflammation, foster regeneration of corneal epithelium and stroma, prevent corneal scarring, and ultimately expedite wound healing. In summary, the SF/CS-based hybrid hydrogel may represent a promising substitute for comprehensive corneal repair and regeneration in severe IK.

Washout-Resistant, pH-Responsive Anti-TMV Nanoimmune Inducer Based on Cellulose Nanocrystals

The application of antiplant virus agents on leaf surfaces faces challenges due to their vulnerability to wear, instability, and limited duration, which in turn jeopardizes plant health and yield. In recent years, high-aspect-ratio nanomaterials have gained prominence as powerful carriers for disease treatment, thanks to their exceptional penetrability and precise drug delivery capabilities. Here, we synthesized a pH-responsive nanoimmune inducer (CNC-AMO) with strong leaf adhesion through a Schiff base reaction, achieved by grafting amino-oligosaccharides (AMOs) on the surface of aldehyde-based CNC (CNC-CHO). Fourier transform infrared spectrometry, zeta potential, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis were used to characterize the CNC-AMO. The CNC-AMO displayed the capability for pH-responsive AMO release, showcasing its potential for targeted and controlled delivery. When applied to plants, the CNC-AMO exhibited impressive anti-TMV efficacy during a weeklong observation period. Meanwhile, the CNC-AMO exhibited remarkable adhesion and scouring resistance on the surfaces of the plant leaves. We strongly believe that the synergy of environmentally friendly synthetic materials, efficient plant virus control, and streamlined scalability positions CNC-AMOs as a promising pesticide for plant virus therapy.

Nanomedicine for the Detection and Treatment of Ocular Bacterial Infections

Ocular bacterial infection is a prevalent cause of blindness worldwide, with substantial consequences for normal human life. Traditional treatments for ocular bacterial infections areless effective, necessitating the development of novel techniques to enable accurate diagnosis, precise drug delivery, and effective treatment alternatives. With the rapid advancement of nanoscience and biomedicine, increasing emphasis has been placed on multifunctional nanosystems to overcome the challenges posed by ocular bacterial infections. Given the advantages of nanotechnology in the biomedical industry, it can be utilized to diagnose ocular bacterial infections, administer medications, and treat them. In this review, the recent advancements in nanosystems for the detection and treatment of ocular bacterial infections are discussed; this includes the latest application scenarios of nanomaterials for ocular bacterial infections, in addition to the impact of their essential characteristics on bioavailability, tissue permeability, and inflammatory microenvironment. Through an in-depth investigation into the effect of sophisticated ocular barriers, antibacterial drug formulations, and ocular metabolism on drug delivery systems, this review highlights the challenges faced by ophthalmic medicine and encourages basic research and future clinical transformation based on ophthalmic antibacterial nanomedicine.

Macrophage targeted iron oxide nanodecoys augment innate immunological and drug killings for more effective Mycobacterium Tuberculosis clearance

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, is still one of the top killers worldwide among infectious diseases. The escape of Mtb from immunological clearance and the low targeting effects of anti-TB drugs remain the substantial challenges for TB control. Iron is particularly required for Mtb growth but also toxic for Mtb in high dosages, which makes iron an ideal toxic decoy for the 'iron-tropic' Mtb. Here, a macrophage-targeted iron oxide nanoparticles (IONPs)-derived IONPs-PAA-PEG-MAN nanodecoy is designed to augment innate immunological and drug killings against intracellular Mtb. IONPs-PAA-PEG-MAN nanodecoy exhibits preferential uptake in macrophages to significantly increase drug uptake with sustained high drug contents in host cells. Moreover, it can serve as a specific nanodecoy for the 'iron-tropic' Mtb to realize the localization of Mtb contained phagosomes surrounding the drug encapsulated nanodecoys and co-localization of Mtb with the drug encapsulated nanodecoys in lysosomes, where the incorporated rifampicin (Rif) can be readily released under acidic lysosomal condition for enhanced Mtb killing. This drug encapsulated nanodecoy can also polarize Mtb infected macrophages into anti-mycobacterial M1 phenotype and enhance M1 macrophage associated pro-inflammatory cytokine (TNF-α) production to trigger innate immunological responses against Mtb. Collectively, Rif@IONPs-PAA-PEG-MAN nanodecoy can synergistically enhance the killing efficiency of intracellular Mtb in in vitro macrophages and ex vivo monocyte-derived macrophages, and also significantly reduce the mycobacterial burdens in the lung of infected mice with alleviated pathology. These results indicate that Rif@IONPs-PAA-PEG-MAN nanodecoy may have a potential for the development of more effective therapeutic strategy against TB by manipulating augmented innate immunity and drug killings.

Inflammation-responsive drug delivery nanosystems for treatment of bacterial-induced sepsis

Sepsis, a complication of dysregulated host immune systemic response to an infection, is life threatening and causes multiple organ injuries. Sepsis is recognized by WHO as a big contributor to global morbidity and mortality. The heterogeneity in sepsis pathophysiology, antimicrobial resistance threat, the slowdown in the development of antimicrobials, and limitations of conventional dosage forms jeopardize the treatment of sepsis. Drug delivery nanosystems are promising tools to overcome some of these challenges. Among the drug delivery nanosystems, inflammation-responsive nanosystems have attracted considerable interest in sepsis treatment due to their ability to respond to specific stimuli in the sepsis microenvironment to release their payload in a precise, targeted, controlled, and rapid manner compared to non-responsive nanosystems. These nanosystems posit superior therapeutic potential to enhance sepsis treatment. This review critically evaluates the recent advances in the design of drug delivery nanosystems that are inflammation responsive and their potential in enhancing sepsis treatment. The sepsis microenvironment's unique features, such as acidic pH, upregulated receptors, overexpressed enzymes, and enhanced oxidative stress, that form the basis for their design have been adequately discussed. These inflammation-responsive nanosystems have been organized into five classes namely: Receptor-targeted nanosystems, pH-responsive nanosystems, redox-responsive nanosystems, enzyme-responsive nanosystems, and multi-responsive nanosystems. Studies under each class have been thematically grouped and discussed with an emphasis on the polymers used in their design, nanocarriers, key characterization, loaded actives, and key findings on drug release and therapeutic efficacy. Further, this information is concisely summarized into tables and supplemented by inserted figures. Additionally, this review adeptly points out the strengths and limitations of the studies and identifies research avenues that need to be explored. Finally, the challenges and future perspectives on these nanosystems have been thoughtfully highlighted.

Polyurethane-based nanofibrous mat containing porphyrin with photosensitivity and bactericidal properties can promote cutaneous tissue healing in rats

The regeneration of cutaneous tissue is one of the most challenging issues in human regenerative medicine. To date, several studies have been done to promote cutaneous tissue healing with minimum side effects. The healing potential of polyurethane (PU)/Poly (caprolactone)-poly (ethylene glycol)-poly (caprolactone) (PCEC)/chitosan (CS) (PCS) nanofibrous mat with cationic photosensitizer meso tetrakis (N-methyl pyridinium-4-yl) porphyrin tetratosylate salt (TMP) was examined. The CS tripolyphosphate nanoparticles (CSNPs) were prepared and loaded by TMP to provide an efficient drug release system (TMPNPs) for delivery of TMP to promote wound healing. In in vitro setting, parameters such as bactericidal effects, cytocompatibility, and hemolytic effects were examined. The healing potential of prepared nanofibrous mats was investigated in a rat model of full-thickness cutaneous injury. PCS/TMP/TMPNPs nanofibers can efficiently release porphyrin in the aqueous phase. The addition of TMPNPs and CS to the PU backbone increased the hydrophilicity, degradation, and reduced mechanical properties. The culture of human fetal foreskin fibroblasts (HFFF2) on PCS/TMP/TMPNPs scaffold led to an increased survival rate and morphological adaptation analyzed by MTT and SEM images. Irradiation with a red laser (635 nm, 3 J/cm2) for the 30 s reduced viability of S. aureus and E. Coli bacteria plated on PCS/TMP and PCS/TMP/TMPNPs nanofibrous mats compared to PU/PCEC (PC) and PU/PCEC/CS (PCS) groups, indicating prominent antibacterial effects of PCS/TMP and PCS/TMP/TMPNPs nanofibrous (p < 0.05). Data indicated that PCS/TMP/TMPNPs mat enhanced healing of the full-thickness excisional wound in a rat model by the reduction of inflammatory response and fibrotic changes compared to the PC, and PCS groups (p < 0.05). Immunofluorescence imaging indicated that levels of Desmoglein were increased in rats that received PCS/TMP/TMPNPs compared to the other groups. It is found that a PU-based nanofibrous mat is an appropriate scaffold to accelerate the healing of injured skin.

Dynamic covalent nano-networks comprising antibiotics and polyphenols orchestrate bacterial drug resistance reversal and inflammation alleviation

New antimicrobial strategies are urgently needed to meet the challenges posed by the emergence of drug-resistant bacteria and bacterial biofilms. This work reports the facile synthesis of antimicrobial dynamic covalent nano-networks (aDCNs) composing antibiotics bearing multiple primary amines, polyphenols, and a cross-linker acylphenylboronic acid. Mechanistically, the iminoboronate bond drives the formation of aDCNs, facilitates their stability, and renders them highly responsive to stimuli, such as low pH and high H₂O₂ levels. Besides, the representative A1B1C1 networks, composed of polymyxin B1(A1), 2-formylphenylboronic acid (B1), and quercetin (C1), inhibit biofilm formation of drug-resistant Escherichia coli, eliminate the mature biofilms, alleviate macrophage inflammation, and minimize the side effects of free polymyxins. Excellent bacterial eradication and inflammation amelioration efficiency of A1B1C1 networks are also observed in a peritoneal infection model. The facile synthesis, excellent antimicrobial performance, and biocompatibility of these aDCNs potentiate them as a much-needed alternative in current antimicrobial pipelines.

Carboxymethyl Chitosan Microgels for Sustained Delivery of Vancomycin and Long-Lasting Antibacterial Effects

Carboxymethyl chitosan (CMCh) is a unique polysaccharide with functional groups that can develop positive and negative charges due to the abundant numbers of amine and carboxylic acid groups. CMCh is widely used in different areas due to its excellent biocompatibility, biodegradability, water solubility, and chelating ability. CMCh microgels were synthesized in a microemulsion environment using divinyl sulfone (DVS) as a crosslinking agent. CMCh microgel with tailored size and zeta potential values were obtained in a single stem by crosslinking CMCh in a water-in-oil environment. The spherical microgel structure is confirmed by SEM analysis. The sizes of CMCh microgels varied from one micrometer to tens of micrometers. The isoelectric point of CMCh microgels was determined as pH 4.4. Biocompatibility of CMCh microgels was verified on L929 fibroblasts with 96.5 ± 1.5% cell viability at 1 mg/mL concentration. The drug-carrying abilities of CMCh microgels were evaluated by loading Vancomycin (Van) antibiotic as a model drug. Furthermore, the antibacterial activity efficiency of Van-loaded CMCh microgels (Van@CMCh) was investigated. The MIC values of the released drug from Van@CMCh microgels were found to be 68.6 and 7.95 µg/mL against E. coli and S. aureus, respectively, at 24 h contact time. Disk diffusion tests confirmed that Van@CMCh microgels, especially for Gram-positive (S. aureus) bacteria, revealed long-lasting inhibitory effects on bacteria growth up to 72 h.

Fighting Methicillin-Resistant Staphylococcus aureus with Targeted Nanoparticles

Antimicrobial resistance (AMR) is considered one of the greatest threats to global health. Methicillin-resistant Staphylococcus aureus (MRSA) remains at the core of this threat, accounting for about 90% of S. aureus infections widespread in the community and hospital settings. In recent years, the use of nanoparticles (NPs) has emerged as a promising strategy to treat MRSA infections. NPs can act directly as antibacterial agents via antibiotic-independent activity and/or serve as drug delivery systems (DDSs), releasing loaded antibiotics. Nonetheless, directing NPs to the infection site is fundamental for effective MRSA treatment so that highly concentrated therapeutic agents are delivered to the infection site while directly reducing the toxicity to healthy human cells. This leads to decreased AMR emergence and less disturbance of the individual's healthy microbiota. Hence, this review compiles and discusses the scientific evidence related to targeted NPs developed for MRSA treatment.

A Novel NQO1 Enzyme-Responsive Polyurethane Nanocarrier for Redox-Triggered Intracellular Drug Release

The design of nano-drug delivery vehicles responsive to tumor microenvironment stimuli has become a crucial aspect in developing cancer therapy in recent years. Among them, the enzyme-responsive nano-drug delivery system is particularly effective, as it utilizes tumor-specific and highly expressed enzymes as precise targets, leading to increased drug release at the target sites, reduced nonspecific release, and improved efficacy while minimizing toxic side effects on normal tissues. NAD(P)H:quinone oxidoreductase 1 (NQO1) is an important reductase associated with cancer and is overexpressed in some cancer cells, particularly in lung and breast cancer. Thus, the design of nanocarriers with high selectivity and responsiveness to NQO1 is of great significance for tumor diagnosis and treatment. It has been reported that under physiological conditions, NQO1 can specifically reduce the trimethyl-locked benzoquinone structure through a two-electron reduction, resulting in rapid lactonization via an enzymatic reaction. Based on this, a novel reduction-sensitive polyurethane (PEG-PTU-PEG) block copolymer was designed and synthesized by copolymerizing diisocyanate, a reduction-sensitive monomer (TMBQ), and poly(ethylene glycol). The successful synthesis of monomers and polymers was verified by nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC). Then, the PEG-PTU-PEG micelles were successfully prepared by self-assembly, and their reductive dissociation behavior in the presence of Na₂S₂O₄ was verified by dynamic light scattering (DLS), ¹H NMR, and GPC. Next, the model drug doxorubicin (DOX) was encapsulated into the hydrophobic core of this polyurethane micelles by microemulsion method. It was observed that the drug-loaded micelles could also achieve a redox response and rapidly release the encapsulated substances. In vitro cell experiments demonstrated that PEG-PTU-PEG micelles had good biocompatibility and a low hemolysis rate (<5%). Furthermore, in the presence of an NQO1 enzyme inhibitor (dicoumarol), lower drug release from micelles was observed in A549 and 4T1 cells by both fluorescence microscopy and flow cytometry assays, but not in NIH-3T3 control cells. Predictably, DOX-loaded micelles also showed lower cytotoxicity in 4T1 cells in the presence of NQO1 enzyme inhibitors. These results indicate that drug-loaded polyurethane micelles could accomplish specific drug release in the reducing environment in the presence of NQO1 enzymes. Therefore, this study provides a new option for the construction of polyurethane nanocarriers for precise targeting and reductive release, which could benefit the intracellular drug-specific release and precision therapy of tumors.

Vancomycin-Loaded Fe3O4/MOF-199 Core/Shell Cargo Encapsulated by Guanidylated-β-Cyclodextrine: An Effective Antimicrobial Nanotherapeutic

This study describes an efficient antimicrobial drug delivery system composed of iron oxide magnetic nanoparticles (Fe₃O₄ NPs) coated by an MOF-199 network. Then, the prepared vancomycin (VAN)-loaded carrier was fully packed in a lattice of beta-cyclodextrin (BCD). For cell adhesion, beta-cyclodextrin has been functionalized with guanidine (Gn) groups within in situ synthetic processes. Afterward, drug loading efficiency and the release patterns were investigated through precise analytical methods. Confocal microscopy has shown that the prepared cargo (formulated as [VAN@Fe₃O₄/MOF-199]BCD-Gn) could be attached to the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial cells in a higher rate than the individual VAN. The presented system considerably increased the antibacterial effects of the VAN with a lower dosage of drug. The cellular experiments such as the zone of inhibition and optical density (OD₆₀₀) have confirmed the enhanced antibacterial effect of the designed cargo. In addition, the MIC/MBC (minimum inhibitory and bactericidal concentrations) values have been estimated for the prepared cargo compared to the individual VAN, revealing high antimicrobial potency of the VAN@Fe₃O₄/MOF-199]BCD-Gn cargo.

Natural Small-Molecule-Based Carrier-Free Self-Assembly Library Originated from Traditional Chinese Herbal Medicine

The carrier-free self-assembly of small molecules opens a new window for the development of nanomaterials. This study is dedicated to developing binary small-molecular self-assemblies derived from phytochemicals in traditional Chinese herbal medicine. Among them, Rhei Radix et Rhizoma and Coptidis Rhizoma are a common pair used in clinics for thousands of years. Here, we found that there were numerous spherical supramolecular nanoparticles (NPs) originated from Rhei Radix et Rhizoma and Coptidis Rhizoma decoction. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) was used to analyze the composition of the supramolecules, and a total of 119 phytochemicals were identified (23 anthraquinones, 31 alkaloids, 24 organic acids, 8 tannins, and other components). Isothermal titration calorimetry (ITC) showed that the interaction between Rhei Radix et Rhizoma and Coptidis Rhizoma was a spontaneous exothermic reaction, indicating that their phytochemicals had the property of self-assembly and interacted to form supramolecules in the decocting process. Furthermore, scanning electron microscopy (SEM), UV, IR, NMR, and ITC were used to verify that rhein and coptisine could self-assemble into nanofibers (Rhe-Cop NFs), while emodin and coptisine could self-assemble into nanoparticles (Emo-Cop NPs). The formation mechanism analysis of the self-assemblies revealed that they were induced by electrostatic attraction, hydrogen bonding, and π-π stacking, forming nanospheres of about 50 nm and nanofibers. The current study not only provides an idea of discovering carrier-free self-assemblies from traditional herbal medicine decoction but also supplies a reference for the design of binary self-assembly of small molecules in the future.

Conformationally restricted, dipeptide-based, self-assembled nanoparticles for efficient vancomycin delivery

Aim: Emergence of vancomycin (Van) resistance, and usage of its higher dose and short half-life are posing a serious concern. Slow and sustained release of Van using a nanodelivery system may overcome these problems. Materials & methods: Arginine-α,β-dehydrophenylalanine (RΔF) was synthesized using solution-phase synthesis which self-assembled into nanospheres. Van was entrapped in the nanoparticles (NPs). In vitro and in vivo efficacy of Van-RΔF was determined using broth microdilution and the mouse thigh infection model, respectively. Results & conclusion: Van-RΔF NPs efficiently inhibited bacterial growth (Staphylococcus aureus), while Van alone showed limited growth inhibition in in vitro. Intravenous administration of Van-RΔF in mice with bacterial thigh infection showed enhanced efficacy (double) compared with Van alone, which indicates its high potential for further development.

Smart Bacteria-Responsive Drug Delivery Systems in Medical Implants

With the rapid development of implantable biomaterials, the rising risk of bacterial infections has drawn widespread concern. Due to the high recurrence rate of bacterial infections and the issue of antibiotic resistance, the common treatments of peri-implant infections cannot meet the demand. In this context, stimuli-responsive biomaterials have attracted attention because of their great potential to spontaneously modulate the drug releasing rate. Numerous smart bacteria-responsive drug delivery systems (DDSs) have, therefore, been designed to temporally and spatially release antibacterial agents from the implants in an autonomous manner at the infected sites. In this review, we summarized recent advances in bacteria-responsive DDSs used for combating bacterial infections, mainly according to the different trigger modes, including physical stimuli-responsive, virulence-factor-responsive, host-immune-response responsive and their combinations. It is believed that the smart bacteria-responsive DDSs will become the next generation of mainstream antibacterial therapies.