Acidic biofilm microenvironment-responsive ROS generation via a protein nanoassembly with hypoxia-relieving and GSH-depleting capabilities for efficient elimination of biofilm bacteria

Reactive oxygen species (ROS) are widely considered to the effective therapeutics for fighting bacterial infections especially those associated with biofilm. However, biofilm microenvironments including hypoxia, limited H2O2, and high glutathione (GSH) level seriously limit the therapeutic efficacy of ROS-based strategies. Herein, we have developed an acidic biofilm microenvironment-responsive antibacterial nanoplatform consisting of copper-dopped bovine serum albumin (CBSA) loaded with copper peroxide (CuO2) synthesized in situ and indocyanine green (ICG). The three-in-one nanotherapeutics (CuO2/ICG@CBSA) are capable of releasing Cu2+ and H2O2 in a slightly acidic environment, where Cu2+ catalyzes the conversion of H2O2 into hydroxyl radical (•OH) and consumes the highly expressed GSH to disrupt the redox homeostasis. With the assistance of an 808 nm laser, the loaded ICG not only triggers the production of singlet oxygen (1O2) by a photodynamic process, but also provides photonic hyperpyrexia that further promotes the Fenton-like reaction for enhancing •OH production and induces thermal decomposition of CuO2 for the O2-self-supplying 1O2 generation. The CuO2/ICG@CBSA with laser irradiation demonstrates photothermal-augmented multi-mode synergistic bactericidal effect and is capable of inhibiting biofilm formation and eradicating the biofilm bacteria. Further in vivo experiments suggest that the CuO2/ICG@CBSA can effectively eliminate wound infections and accelerate wound healing. The proposed three-in-one nanotherapeutics with O2/H2O2-self-supplied ROS generating capability show great potential in treating biofilm-associated bacterial infections. STATEMENT OF SIGNIFICANCE: Here, we have developed an acidic biofilm microenvironment-responsive nanoplatform consisting of copper-dopped bovine serum albumin (CBSA) loaded with copper peroxide (CuO2) synthesized in situ and indocyanine green (ICG). The nanotherapeutics (CuO2/ICG@CBSA) are capable of releasing Cu2+ and H2O2 in an acidic environment, where Cu2+ catalyzes the conversion of H2O2 into •OH and consumes the overexpressed GSH to improve oxidative stress. With the aid of an 808 nm laser, ICG provides photonic hyperpyrexia for enhancing •OH production, and triggers O2-self-supplying 1O2 generation. CuO2/ICG@CBSA with laser irradiation displays photothermal-augmented multi-mode antibacterial and antibiofilm effect. Further in vivo experiments prove that CuO2/ICG@CBSA effectively eliminates wound infection and promotes wound healing. The proposed three-in-one nanotherapeutics show great potential in treating biofilm-associated bacterial infections.

Rational design of a Nano-Antibiotic chitosan hydrogel for the bacterial infection Therapy: In vitro & ex vivo Assessments

In modern times, many antibiotics have become less effective as microorganisms develop resistance. Besides antibiotic resistance, another bacterial strategy that contributes to the capacity to withstand antimicrobials is biofilm formation. Because of these bacterial survival strategies, the desired response cannot be achieved with conventional treatment. Considering the limited discovery of new compounds, the most logical approach is to reconstruct existing antimicrobial molecules with nano-drug delivery systems. With this scientific approach, the aim of the study is to develop a novel nano-antibiotic hydrogel formulation containing silver nanoparticles, chitosan, and amoxicillin. Endodontic disease was used as a model of biofilm-mediated infection, and the antibacterial activity of nano-antibiotic hydrogel was evaluated with the E. faecalis standard bacterial strain. By adopting the Box-Behnken design for the optimisation of formulation variables, an innovative pharmaceutical formulation with antimicrobial and antibiofilm activity was successfully obtained. Further characterisation studies, including nanoparticle characterisation, in vitro cytotoxicity, and ex vivo activity studies, were carried out on dental samples using the optimised formulation. All results were compared with antimicrobial agents routinely used in endodontic treatment. The findings mainly conclude that the optimised nano-antibiotic hydrogel may be an alternative antimicrobial formulation since it is non-cytotoxic and exhibits high antibiofilm activity.

Nanoarchitectonics of in Situ Antibiotic-Releasing Acicular Nanozymes for Targeting and Inducing Cuproptosis-like Death to Eliminate Drug-Resistant Bacteria

A series of progress has been made in the field of antimicrobial use of nanozymes due to their superior stability and decreased susceptibility to drug resistance. However, catalytically generated reactive oxygen species (ROS) are insufficient for coping with multidrug-resistant organisms (MDROs) in complex wound environments due to their low targeting ability and insufficient catalytic activity. To address this problem, chemically stable copper-gallic acid-vancomycin (CuGA-VAN) nanoneedles were successfully constructed by a simple approach for targeting bacteria; these nanoneedles exhibit OXD-like and GSH-px-like dual enzyme activities to produce ROS and induce bacterial cuproptosis-like death, thereby eliminating MDRO infections. The results of in vitro experiments showed that the free carboxylic acid of GA could react with the free ammonia of teichoic acid in the methicillin-resistant Staphylococcus aureus (MRSA) cell wall skeleton. Thus, CuGA-VAN nanoneedles can rapidly "capture" MRSA in liquid environments, releasing ROS, VAN and Cu2+ on bacterial surfaces to break down the MRSA barrier, destroying the biofilm. In addition, CuGA-VAN effectively promoted wound repair cell proliferation and angiogenesis to facilitate wound healing while ensuring biosafety. According to transcriptome sequencing, highly internalized Cu2+ causes copper overload toxicity; downregulates genes related to the bacterial glyoxylate cycle, tricarboxylic acid cycle, and oxidative respiratory chain; and induces lipid peroxidation in the cytoplasm, leading to bacterial cuproptosis-like death. In this study, CuGA-VAN was cleverly designed to trigger a cascade reaction of targeting, drug release, ROS-catalyzed antibacterial activity and cuproptosis-like death. This provides an innovative idea for multidrug-resistant infections.

2D Janus carrier-enabled trojan horse: Gallium delivery for the sequential therapy of biofilm associated infection

Biofilm-associated infections (BAIs) continue to pose a major challenge in the medical field. Nanomedicine, in particular, promises significant advances in combating BAIs through the introduction of a variety of nanomaterials and nano-antimicrobial strategies. However, studies to date have primarily focused on the removal of the bacterial biofilm and neglect the subsequent post-biofilm therapeutic measures for BAIs, rendering pure anti-biofilm strategies insufficient for the holistic recovery of affected patients. Herein, we construct an emerging dual-functional composite nanosheet (SiHx@Ga) that responds to pHs fluctuation in the biofilm microenvironment to enable a sequential therapy of BAIs. In the acidic environment of biofilm, SiHx@Ga employs the self-sensitized photothermal Trojan horse strategy to effectively impair the reactive oxygen species (ROS) defense system while triggering oxidative stress and lipid peroxidation of bacteria, engendering potent antibacterial and anti-biofilm effects. Surprisingly, in the post-treatment phase, SiHx@Ga adsorbs free pathogenic nucleic acids released after biofilm destruction, generates hydrogen with ROS-scavenging and promotes macrophage polarization to the M2 type, effectively mitigating damaging inflammatory burst and promoting tissue healing. This well-orchestrated strategy provides a sequential therapy of BAIs by utilizing microenvironmental variations, offering a conceptual paradigm shift in the field of nanomedicine anti-infectives.

A self-supplied hydrogen peroxide and nitric oxide-generating nanoplatform enhances the efficacy of chemodynamic therapy for biofilm eradication

Bacterial biofilms present a profound challenge to global public health, often resulting in persistent and recurrent infections that resist treatment. Chemodynamic therapy (CDT), leveraging the conversion of hydrogen peroxide (H2O2) to highly reactive hydroxyl radicals (•OH), has shown potential as an antibacterial approach. Nonetheless, CDT struggles to eliminate biofilms due to limited endogenous H2O2 and the protective extracellular polymeric substances (EPS) within biofilms. This study introduces a multifunctional nanoplatform designed to self-supply H2O2 and generate nitric oxide (NO) to overcome these hurdles. The nanoplatform comprises calcium peroxide (CaO2) for sustained H2O2 production, a copper-based metal-organic framework (HKUST-1) encapsulating CaO2, and l-arginine (l-Arg) as a natural NO donor. When exposed to the acidic microenvironment within biofilms, the HKUST-1 layer decomposes, releasing Cu2+ ions and l-Arg, and exposing the CaO2 core to initiate a cascade of reactions producing reactive species such as H2O2, •OH, and superoxide anions (•O2-). Subsequently, H2O2 catalyzes l-Arg to produce NO, which disperses the biofilm and reacts with •O2- to form peroxynitrite, synergistically eradicating bacteria with •OH. In vitro assays demonstrated the nanoplatform's remarkable antibiofilm efficacy against both Gram-positive Methicillin-resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, significantly reducing bacterial viability and EPS content. In vivo mouse model experiments validated the nanoplatform's effectiveness in eliminating biofilms and promoting infected wound healing without adverse effects. This study represents a breakthrough in overcoming traditional CDT limitations by integrating self-supplied H2O2 with NO's biofilm-disrupting capabilities, offering a promising therapeutic strategy for biofilm-associated infection.

H2O2-Activatable Liposomal Nanobomb Capable of Generating Hypoxia-Irrelevant Alkyl Radicals by Photo-Triggered Cascade Reaction for High-Performance Elimination of Biofilm Bacteria

High H2O2 levels are widely present at the infection sites or in the biofilm microenvironment. Herein, hemin with peroxidase-like catalytic activity and its substrate, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), are simultaneously introduced into a liposomal nanoparticle containing thermosensitive 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIBI)-loaded bovine serum albumin (BAG), rationally constructing an H2O2-activatable liposomal nanobomb (Lipo@BHA) for combating biofilm-associated bacterial infections with high performance. In the presence of H2O2, hemin can catalyze the conversion of ABTS into its oxidized form (ABTS·+) with strong near-infrared (NIR) absorption, which produces photonic hyperpyrexia to cause the decomposition of AIBI into oxygen-independent alkyl radicals (·R) and nitrogen (N2) microbubbles. The former not only directly damage bacterial cells but also significantly accelerates the oxidization of ABTS to ABTS·+ for augmenting photothermal-triggered generation of ·R. Interestingly, the released N2 can induce transient cavitation to rupture lysosomal nanoparticle and improve the biofilm permeability, thereby enhancing the antibiofilm effect of Lipo@BHA. The proposed Lipo@BHA exhibits satisfactory multi-mode combination antibacterial properties. Through endogenous H2O2-activated cascade reaction, Lipo@BHA achieves remarkable hypoxia-irrelevant ·R therapy of biofilm-associated wound infections with low cytotoxicity and good in vivo biosafety. Therefore, this work presents a versatile H2O2-activatable cascade ·R generation strategy for biofilm-specific therapeutic applications.

AMP-Mimetic Antimicrobial Polymer-Involved Synergic Therapy with Various Coagents for Improved Efficiency

The misuse of antibiotics contributes to the emergence of multidrug-resistant (MDR) bacteria. Infections caused by MDR bacteria are rapidly evolving into a significant threat to global healthcare due to the lack of effective and safe treatments. Antimicrobial peptides (AMPs) with broad-spectrum antibacterial activity kill bacteria generally through a membrane disruption mechanism; hence, they tend not to induce resistance readily. However, AMPs exhibit disadvantages, such as high cost and susceptibility to proteolytic degradation, which limit their clinical application. AMP-mimetic antimicrobial polymers, with low cost, stability to proteolysis, broad-spectrum antimicrobial activity, negligible antimicrobial resistance, and rapid bactericidal effect, have received extensive attention as a new type of antibacterial drugs. Lately, AMP-mimetic polymer-involved synergic therapy provides a superior alternative to combat MDR bacteria by distinct mechanisms. In this Review, we summarize the AMP-mimetic antimicrobial polymers involved in synergic therapy, particularly focusing on the different combinations between the polymers with commercially available antimicrobials, organic small molecule photosensitizers, inorganic nanomaterials, and nitric oxide.

Synthesis of Coumarin-Based Photosensitizers for Enhanced Antibacterial Type I/II Photodynamic Therapy

Photodynamic therapy (PDT) is an effective method for treating microbial infections by leveraging the unique photophysical properties of photosensitizing agents, but issues such as fluorescence quenching and the restricted generation of reactive oxygen species (ROS) under hypoxic conditions still remain. In this study, we successfully synthesized and designed a coumarin-based aggregation-induced emission luminogen (AIEgen), called ICM, that shows a remarkable capacity for type I ROS and type II ROS generation. The 1O2 yield of ICM is 0.839. The ROS it produces include hydroxyl radicals (HO•) and superoxide anions (O2•-), with highly effective antibacterial properties specifically targeting Staphylococcus aureus (a Gram-positive bacterium). Furthermore, ICM enables broad-spectrum fluorescence imaging and exhibits excellent biocompatibility. Consequently, ICM, as a potent type I photosensitizer for eliminating pathogenic microorganisms, represents a promising tool in addressing the threat posed by these pathogens.

Engineered Probiotic Bio-Heterojunction with Robust Antibiofilm Modality via "Eating" Extracellular Polymeric Substances for Wound Regeneration

The compact three-dimensional (3D) structure of extracellular polymeric substances (EPS) within biofilms significantly hinders the penetration of antimicrobial agents, making biofilm eradication challenging and resulting in persistent biofilm-associated infections. To address this challenge, a solution is proposed: a probiotic bio-heterojunction (P-bioHJ) combining Lactobacillus rhamnosus with MXene (Ti3C2) quantum dots (MQDs)/FeS heterojunction. This innovation aims to break down the saccharides in EPS, enabling effective combat against biofilm-associated infections. Initially, the P-bioHJ targets saccharides through metabolic processes, causing the collapse of EPS and allowing infiltration into bacterial colonies. Simultaneously, upon exposure to near-infrared (NIR) irradiation, the P-bioHJ produces reactive oxygen species (ROS) and thermal energy, deploying physical mechanisms to combat bacterial biofilms effectively. Following antibiofilm treatment, the P-bioHJ adjusts the oxidative environment, reduces wound inflammation by scavenging ROS, boosts antioxidant enzyme activity, and mitigates the NF-κB inflammatory pathway, thereby accelerating wound healing. In vitro and in vivo experiments confirm the exceptional antibiofilm, antioxidant/anti-inflammatory, and wound-regeneration properties of P-bioHJ. In conclusion, this study provides a promising approach for treating biofilm-related infections.

Bioinspired green synthesis of ZnO nanoparticles by marine-derived Streptomyces plicatus and its multifaceted biomedicinal properties

The present study explores the bioinspired green synthesis of zinc oxide nanoparticles (ZnONPs) using marine Streptomyces plicatus and its potent antibacterial, antibiofilm activity against dental caries forming Streptococcus mutans MTCC and S. mutans clinical isolate (CI), cytotoxicity against oral KB cancer cells, hemolysis against blood erythrocytes and artemia toxicity. The bioinspired ZnONPs showed a distinctive absorption peak at 375 nm in UV-Vis spectra, the FT-IR spectra divulged the active functional groups, and XRD confirmed the crystalline nature of the nanoparticles with an average grain size of 41.76 nm. SEM analysis evidenced hexagonal morphology, and EDX spectra affirmed the presence of zinc. The ZnONPs exerted higher antagonistic activity against S. mutans MTCC (Inhibitory zone: 19 mm; MIC: 75 μg/ml) than S. mutans CI (Inhibitory zone: 17 mm; MIC: 100 μg/ml). Results of biofilm inhibitory activity showed a concentration-dependent reduction with S. mutans MTCC (15 %-95 %) more sensitive than S. mutans CI (13 %-89 %). The 50 % biofilm inhibitory concentration (BIC50) of ZnONPs against S. mutans MTCC was considerably lower (71.76 μg/ml) than S. mutans CI (78.13 μg/ml). Confocal Laser Scanning Microscopic visuals clearly implied that ZnONPs effectively distorted the biofilm architecture of both S. mutans MTCC and S. mutans CI. This was further bolstered by a remarkable rise in protein leakage (19 %-85 %; 15 %-77 %) and a fall in exopolysaccharide production (34 mg-7 mg; 49 mg-12 mg). MTT cytotoxicity of ZnONPs recorded an IC50 value of 22.06 μg/ml against KB cells. Acridine orange/ethidium bromide staining showed an increasing incidence of apoptosis in KB cells. Brine shrimp cytotoxicity using Artemia salina larvae recorded an LC50 value of 78.41 μg/ml. Hemolysis assay substantiated the biocompatibility of the ZnONPs. This study underscores the multifaceted application of bioinspired ZnONPs in dentistry.

Bioinspired ferromagnetic NiFe2O4 nanoparticles: Eradication of fungal and drug-resistant bacterial pathogens and their established biofilm

Nickel ferrite nanoparticles (NiFe2O4 NPs) were synthesized using the medicinally important plant Aloe vera leaf extract, and their structural, morphological, and magnetic properties were characterized by x-ray diffraction (XRD), fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and vibrating sample magnetometer (VSM). The synthesized NPs were soft ferromagnetic and spinel in nature, with an average particle size of 22.2 nm. To the best of our understanding, this is the first comprehensive investigation into the antibacterial, anticandidal, antibiofilm, and antihyphal properties of NiFe2O4 NPs against C. albicans as well as drug-resistant gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and gram-negative multidrug resistant Pseudomonas aeruginosa (MDR-P. aeruginosa) bacteria. NiFe2O4 NPs showed potent antimicrobial activity (MIC 1.6-2 mg/mL) against the test pathogens. NiFe2O4 NPs at 0.5 mg/mL suppressed biofilm formation by 49.5-53.1 % in test pathogens. The study found that the NPs not only prevent the formation of biofilm, but also eliminate existing mature biofilms by 50.5-75.79 % at 0.5 mg/mL, which was further validated by SEM. SEM examination revealed a reduction in the number of cells that form biofilms and adhere to the surface. Additionally, it considerably impeded the colonization and aggregation of the biofilm strains on the glass surface. Light microscopic examination demonstrated that NPs effectively prevent the expansion of hyphae, filaments, and yeast-to-hyphae transformation in C. albicans, resulting in a substantial decrease in their ability to cause infection. Moreover, SEM images of the treated cells exhibited the presence of wrinkles, deformities, and impaired cell walls, which suggests an alteration and instability of the membrane. This study demonstrated the efficacy of the greenly manufactured NPs in suppressing the proliferation of candida, drug-resistant bacteria, and their preexisting biofilms, as well as yeast-to-hyphae transformation. Therefore, these NPs with broad spectrum applications could be utilized in health settings to mitigate biofilm-related health conditions caused by pathogenic microbial strains.

An intratumor bacteria-targeted DNA nanocarrier for multifaceted tumor microenvironment intervention

Intratumor bacteria, which are involved with complex tumor development mechanisms, can compromise the therapeutic efficiencies of cancer chemotherapeutics. Therefore, the development of anti-tumor agents targeting intratumor bacteria is crucial in overcoming the drug inactivation induced by bacteria colonization. In this study, a double-bundle DNA tetrahedron-based nanocarrier is developed for intratumor bacteria-targeted berberine (Ber) delivery. The combination of aptamer modification and high drug loading efficacy endow the DNA nanocarrier TA@B with enhanced delivery performance in anti-tumor therapy without obvious systemic toxicity. The loaded natural isoquinoline alkaloid Ber exhibits enhanced antimicrobial, anticancer, and immune microenvironment regulation effects, ultimately leading to efficient inhibition of tumor proliferation. This intratumor bacteria-targeted DNA nanoplatform provides a promising strategy in intervening the bacteria-related microenvironment and facilitating tumor therapy.

Bioinspired Hybrid Nanostructured PEEK Implant with Enhanced Antibacterial and Anti-inflammatory Synergy

Implant-associated infections and excessive immune responses are two major postsurgical issues for successful implantation. However, conventional strategies including antibiotic treatment and inflammatory regulation are always compromised due to the comodification of various biochemical agents and instances of functional interference. It is imperative to provide implant surfaces with satisfactory antibacterial and anti-inflammatory properties. Here, a dual-effect nanostructured polyetheretherketone (PEEK) surface (NP@PDA/Zn) with bionic mechano-bactericidal nanopillars and immobilized immunomodulatory Zn2+ is designed. The constructed hybrid nanopillars display remarkable antibacterial performance against Gram-negative and Gram-positive strains through the synergy of physical and chemical bactericidal effects imposed by nanopillars and Zn2+. Meanwhile, the immunoregulatory property is evaluated through the investigation of macrophage polarization both in vitro and in vivo, and the results reveal that NP@PDA/Zn could downregulate the expression of M1-related cytokines and decrease the M1 macrophage recruitment to lower the inflammatory response. Notably, the surface exhibited exceptional biocompatibility with discerning biocidal activity between bacterial and mammalian cells and antioxidant performance that effectively scavenges ROS, minimizing potential cytotoxicity. Taken together, NP@PDA/Zn presents a convenient and promising strategy of combining synergistic bactericidal activity and inflammatory regulation without any mutual interference, which can support the development of multifunctional implant-associated materials.

Surface-Charge Tuned Polymeric Nanoemulsions for Carvacrol Delivery in Interkingdom Biofilms

Biofilms, intricate microbial communities entrenched in extracellular polymeric substance (EPS) matrices, pose formidable challenges in infectious disease treatment, especially in the context of interkingdom biofilms prevalent in the oral environment. This study investigates the potential of carvacrol-loaded biodegradable nanoemulsions (NEs) with systematically varied surface charges─cationic guanidinium (GMT-NE) and anionic carboxylate (CMT-NE). Zeta potentials of +25 mV (GMT-NE) and -33 mV (CMT-NE) underscore successful nanoemulsion fabrication (∼250 nm). Fluorescent labeling and dynamic tracking across three dimensions expose GMT-NE's superior diffusion into oral biofilms, yielding a robust antimicrobial effect with 99.99% killing for both streptococcal and Candida species and marked reductions in bacterial cell viability compared to CMT-NE (∼4-log reduction). Oral mucosa tissue cultures affirm the biocompatibility of both NEs with no morphological or structural changes, showcasing their potential for combating intractable biofilm infections in oral environment. This study advances our understanding of NE surface charges and their interactions within interkingdom biofilms, providing insights crucial for addressing complex infections involving bacteria and fungi in the demanding oral context.

Reaction-Induced Self-Assembly of Polymyxin Mitigates Cytotoxicity and Reverses Drug Resistance

Polymyxins have been regarded as an efficient therapeutic against many life-threatening, multidrug resistant Gram-negative bacterial infections; however, the cytotoxicity and emergence of drug resistance associated with polymyxins have greatly hindered their clinical potential. Herein, the reaction-induced self-assembly (RISA) of polymyxins and natural aldehydes in aqueous solution is presented. The resulting assemblies effectively mask the positively charged nature of polymyxins, reducing their cytotoxicity. Moreover, the representative PMBA4 (composed of polymyxin B (PMB) and (E)-2-heptenal (A4)) assemblies demonstrate enhanced binding to Gram-negative bacterial outer membranes and exhibit multiple antimicrobial mechanisms, including increased membrane permeability, elevated bacterial metabolism, suppression of quorum sensing, reduced ATP synthesis, and potential reduction of bacterial drug resistance. Remarkably, PMBA4 assemblies reverse drug resistance in clinically isolated drug-resistant strains of Gram-negative bacteria, demonstrating exceptional efficacy in preventing and eradicating bacterial biofilms. PMBA4 assemblies efficiently eradicate Gram-negative bacterial biofilm infections in vivo and alleviate inflammatory response. This RISA strategy offers a practical and clinically applicable approach to minimize side effects, reverse drug resistance, and prevent the emergence of resistance associated with free polymyxins.

Recent advances in the pathogenesis and prevention strategies of dental calculus

Dental calculus severely affects the oral health of humans and animal pets. Calculus deposition affects the gingival appearance and causes inflammation. Failure to remove dental calculus from the dentition results in oral diseases such as periodontitis. Apart from adversely affecting oral health, some systemic diseases are closely related to dental calculus deposition. Hence, identifying the mechanisms of dental calculus formation helps protect oral and systemic health. A plethora of biological and physicochemical factors contribute to the physiological equilibrium in the oral cavity. Bacteria are an important part of the equation. Calculus formation commences when the bacterial equilibrium is broken. Bacteria accumulate locally and form biofilms on the tooth surface. The bacteria promote increases in local calcium and phosphorus concentrations, which triggers biomineralization and the development of dental calculus. Current treatments only help to relieve the symptoms caused by calculus deposition. These symptoms are prone to relapse if calculus removal is not under control. There is a need for a treatment regime that combines short-term and long-term goals in addressing calculus formation. The present review introduces the mechanisms of dental calculus formation, influencing factors, and the relationship between dental calculus and several systemic diseases. This is followed by the presentation of a conceptual solution for improving existing treatment strategies and minimizing recurrence.

Cell Wall Binding Strategies Based on Cu3SbS3 Nanoparticles for Selective Bacterial Elimination and Promotion of Infected Wound Healing

Utilizing nanomaterials as an alternative to antibiotics, with a focus on maintaining high biosafety, has emerged as a promising strategy to combat antibiotic resistance. Nevertheless, the challenge lies in the indiscriminate attack of nanomaterials on both bacterial and mammalian cells, which limits their practicality. Herein, Cu3SbS3 nanoparticles (NPs) capable of generating reactive oxygen species (ROS) are discovered to selectively adsorb and eliminate bacteria without causing obvious harm to mammalian cells, thanks to the interaction between O of N-acetylmuramic acid in bacterial cell walls and Cu of the NPs. Coupled with the short diffusion distance of ROS in the surrounding medium, a selective antibacterial effect is achieved. Additionally, the antibacterial mechanism is then identified: Cu3SbS3 NPs catalyze the generation of O2•-, which has subsequently been conversed by superoxide dismutase to H2O2. The latter is secondary catalyzed by the NPs to form •OH and 1O2, initiating an in situ attack on bacteria. This process depletes bacterial glutathione in conjunction with the disruption of the antioxidant defense system of bacteria. Notably, Cu3SbS3 NPs are demonstrated to efficiently impede biofilm formation; thus, a healing of MRSA-infected wounds was promoted. The bacterial cell wall-binding nanoantibacterial agents can be widely expanded through diversified design.

Gram-negative bacteria recognition and photodynamic elimination by Zn-DPA based sensitizers

The abuse and overuse of antibiotics let drug-resistant bacteria emerges. Antibacterial photodynamic therapy (APDT) has shown outstanding merits to eliminate the drug-resistant bacteria via cytotoxic reactive oxygen species produced by irradiating photosensitizer. However, most of photosensitizers are not effective for Gram-negative bacteria elimination. Herein conjugates of NBS, a photosensitizer, linked with one (NBS-DPA-Zn) or two (NBS-2DPA-Zn) equivalents of zinc-dipicolylamine (Zn-DPA) have been designed to achieve the functional recognition of different bacteria. Due to the cationic character of NBS and metal transfer channel effect of Zn-DPA, NBS-DPA-Zn exhibited the first regent to distinguish P. aeruginosa from other Gram-negative bacteria. Whereas NBS-2DPA-Zn showed broad-spectrum antibacterial effect because the two arm of double Zn-DPA enhanced interactions with anionic membranes of bacteria, led the bacteria aggregation and thus provided the efficacy of APDT to bacteria and corresponding biofilm. In combination with a hydrogel of Pluronic, NBS-2DPA-Zn@gel shows promising clinical application in mixed bacterial diabetic mouse model infection. This might propose a new method that can realize functional identification and elimination of bacteria through intelligent regulation of Zn-DPA, and shows excellent potential for antibacterial application.

Gold nanoclusters cure implant infections by targeting biofilm

The biofilm-mediated implant infections pose a huge threat to human health. It is urgent to explore strategies to reverse this situation. Herein, we design 3-amino-1,2,4-triazole-5-thiol (ATT)-modified gold nanoclusters (AGNCs) to realize biofilm-targeting and near-infrared (NIR)-II light-responsive antibiofilm therapy. The AGNCs can interact with the bacterial extracellular DNA through the formation of hydrogen bonds between the amine groups on the ATT and the hydroxyl groups on the DNA. The AGNCs show photothermal properties even at a low power density (0.5 W/cm2) for a short-time (5 min) irradiation, making them highly effective in eradicating the biofilm with a dispersion rate up to 90 %. In vivo infected catheter implantation model demonstrates an exceptional high ability of the AGNCs to eradicate approximately 90 % of the bacteria encased within the biofilms. Moreover, the AGNCs show no detectable toxicity or systemic effects in mice. Our study suggests the great potential of the AGNCs for long-term prevention and elimination of the biofilm-mediated infections.

pH-Responsive Charge Convertible Hyperbranched Poly(ionic liquid) Nanoassembly with High Biocompatibility for Resistance-Free Antimicrobial Applications

As a potential alternative to antibiotics, hyperbranched poly(ionic liquid)s (HPILs) have demonstrated significant potential in combating bacterial biofilms. However, their high cation density poses a high risk of toxicity, greatly limiting their in vivo applications. In this study, we constructed a biocompatible HPIL (HPIL-Glu) from a hyperbranched polyurea core with modified terminals featuring charge-convertible ionic liquids. These ionic liquid moieties consist of an ammonium-based cation and a gluconate (Glu) organic counter. HPIL-Glu could form a homogeneous nanoassembly in water and exhibited a pH-responsive charge conversion property. Under neutral conditions, Glu shielded the positively charged surface, minimizing the toxicity. In a mildly acidic environment, Glu protonation exposes cationic moieties to biofilm eradication. Comprehensive antimicrobial assessments demonstrate that HPIL-Glu effectively kills bacteria and promotes the healing of bacteria-infected chronic wounds. Furthermore, prolonged exposure to HPIL-Glu does not induce antimicrobial resistance.

A normalized parameter for comparison of biofilm dispersants in vitro

Dispersal of infectious biofilms increases bacterial concentrations in blood. To prevent sepsis, the strength of a dispersant should be limited to allow the immune system to remove dispersed bacteria from blood, preferably without antibiotic administration. Biofilm bacteria are held together by extracellular polymeric substances that can be degraded by dispersants. Currently, comparison of the strength of dispersants is not possible by lack of a suitable comparison parameter. Here, a biofilm dispersal parameter is proposed that accounts for differences in initial biofilm properties, dispersant concentration and exposure time by using PBS as a control and normalizing outcomes with respect to concentration and time. The parameter yielded near-identical values based on dispersant-induced reductions in biomass or biofilm colony-forming-units and appeared strain-dependent across pathogens. The parameter as proposed is largely independent of experimental methods and conditions and suitable for comparing different dispersants with respect to different causative strains in particular types of infection.

Adenosine Triphosphate-Activated Cascade Reactor for On-Demand Antibacterial Treatment Through Controlled Hydroxyl Radical Generation

Nanozymes have shown promise for antibacterial applications, but their effectiveness is often hindered by low catalytic performances in physiological conditions and uncontrolled production of hydroxyl radicals (·OH). To address these limitations, a comprehensive approach is presented through the development of an adenosine triphosphate (ATP)-activated cascade reactor (GGPcs). The GGPcs reactor synergistically combines the distinct properties of zeolitic imidazolate framework-8 (ZIF-8) and chitosan-integrated hydrogel microsphere. The ZIF-8 allows for the encapsulation of G-quadruplex/hemin DNAzyme to achieve ATP-responsive ·OH generation at neutral pH, while the hydrogel microsphere creates a confinement environment that facilitates glucose oxidation and provides a sufficient supply of H2O2. Importantly, the integrated chitosan in the hydrogel microsphere shields ZIF-8 from undesired disruption caused by gluconic acid, ensuring the responsive specificity of ZIF-8 toward ATP. By activating GGPcs with ATP secreted by bacteria, its effectiveness as an antibacterial agent is demonstrated for the on-demand treatment of bacterial infection with minimal side effects. This comprehensive approach has the potential to facilitate the design of advanced nanozyme systems and broaden their biological applications.

Deciphering the Drug Delivery Potential of Milk Exosome Nanovesicles for Aminobenzylpenicillin Therapeutic Efficacy against Contagious Staphylococcus Aureus in Bovine Mastitis

The emergence of antimicrobial resistance and failure of antibiotic treatment are challenging tasks for managing bovine mastitis, which is mainly caused by the contagious Staphylococcus aureus (S. aureus).To overcome these difficulties, there is an urgent need for a novel drug system. In the present study, the aim is to develop next-generation therapeutics against S. aureus by harnessing the drug delivery potential of milk nanovesicles called milk exosomes (mENs). In the present work, a drug system is developed by encapsulating aminobenzylpenicillin (AMP) in mENs (mENs-AMP). Electron microscopy and zeta-sizer results indicate that the size of mENs-AMP ranged from 55.79 ± 2.8 to 85.53 ± 7.4 nm. The AMP loading efficiency in mENs is 88.61% with its sustained release. Fluorescence spectroscopy results indicated that mENs are biocompatible with mammary epithelial cells. In vitro studies show that the antibacterial activity and the minimum inhibitory concentrations of mENs-AMP are eleven times greater and four times lower than that of unencapsulated AMP, respectively. The mENs-AMP exhibit significantly higher therapeutic efficacy than AMP at the same dosage and treatment frequency. Validation of this approach is demonstrated in mastitis-affected animals through an observation in the reduction of somatic cell counts and bacterial loads in the milk of treated animals.

Recent advances in micro/nanomotors for antibacterial applications

Currently, the rapid spread of multidrug-resistant bacteria derived from the indiscriminate use of traditional antibiotics poses a significant threat to public health worldwide. Moreover, established bacterial biofilms are extremely difficult to eradicate because of their high tolerance to traditional antimicrobial agents and extraordinary resistance to phagocytosis. Hence, it is of universal significance to develop novel robust and efficient antibacterial strategies to combat bacterial infections. Micro/nanomotors exhibit many intriguing properties, including enhanced mass transfer and micro-mixing resulting from their locomotion, intrinsic antimicrobial capabilities, active cargo delivery, and targeted treatment with precise micromanipulation, which facilitate the targeted delivery of antimicrobials to infected sites and their deep permeation into sites of bacterial biofilms for fast inactivation. Thus, the ideal antimicrobial activity of antibacterial micro/nanorobots makes them desirable alternatives to traditional antimicrobial treatments and has aroused extensive interest in recent years. In this review, recent advancements in antibacterial micro/nanomotors are briefly summarized, focusing on their synthetic methods, propulsion mechanism, and versatile antibacterial applications. Finally, some personal insights into the current challenges and possible future directions to translate proof-of-concept research to clinic application are proposed.

Nanomaterials with Enzyme-like Properties for Combatting Foodborne Pathogen Infections: Classifications, Mechanisms, and Applications in Food Preservation

During the transportation and storage of food, foodborne spoilage caused by bacterial and biofilm infection is prone to occur, leading to issues such as short shelf life, economic loss, and sensory quality instability. Therefore, the development of novel and efficient antibacterial agents capable of efficiently inhibiting bacteria throughout various stages of food processing, transportation, and storage is strongly recommended by researchers. The emergence of nanozymes is considered to be an effective candidate for inhibiting foodborne bacteria agents in the food industry. As potent antibacterial agents, nanozymes have the advantages of low cost, high stability, strong broad-spectrum antibacterial ability, and biocompatibility. Herein, we aim to summarize the classification status of various nanozymes. Furthermore, the general catalytic bacteriostatic mechanism of nanozymes against intracellular bacteria, planktonic bacteria, and biofilm activities are highlighted, mainly concerning the destruction of cell walls and/or membranes, reactive oxygen species regulation, HOBr/Cl generation, damage of intracellular components, and so forth. In particular, the review focuses on the pivotal role of nanozymes as antibacterial agents and delivery vehicles in the fields of food preservation applications. We look forward to the future prospects, especially in the field of food preservation, to promote broader applications based on antimicrobial nanozymes.

Biopolymer based nanoparticles and their therapeutic potential in wound healing - A review

Nanoparticles (NPs) have been extensively investigated for their potential in nanomedicine. There is a significant level of enthusiasm about the potential of NPs to bring out a transformative impact on modern healthcare. NPs can serve as effective wound dressings or delivery vehicles due to their antibacterial and pro-wound-healing properties. Biopolymer-based NPs can be manufactured using various food-grade biopolymers, such as proteins, polysaccharides, and synthetic polymers, each offering distinct properties suitable for different applications which include collagen, polycaprolactone, chitosan, alginate, and polylactic acid, etc. Their biodegradable and biocompatible nature renders them ideal nanomaterials for applications in wound healing. Additionally, the nanofibers containing biopolymer-based NPs have shown excellent anti-bacterial and wound healing activity like silver NPs. These NPs represent a paradigm shift in wound healing therapies, offering targeted and personalized solutions for enhanced tissue regeneration and accelerated wound closure. The current review focuses on biopolymer NPs with their applications in wound healing.

Sensing, Imaging, and Therapeutic Strategies Endowing by Conjugate Polymers for Precision Medicine

Conjugated polymers (CPs) have promising applications in biomedical fields, such as disease monitoring, real-time imaging diagnosis, and disease treatment. As a promising luminescent material with tunable emission, high brightness and excellent stability, CPs are widely used as fluorescent probes in biological detection and imaging. Rational molecular design and structural optimization have broadened absorption/emission range of CPs, which are more conductive for disease diagnosis and precision therapy. This review provides a comprehensive overview of recent advances in the application of CPs, aiming to elucidate their structural and functional relationships. The fluorescence properties of CPs and the mechanism of detection signal amplification are first discussed, followed by an elucidation of their emerging applications in biological detection. Subsequently, CPs-based imaging systems and therapeutic strategies are illustrated systematically. Finally, recent advancements in utilizing CPs as electroactive materials for bioelectronic devices are also investigated. Moreover, the challenges and outlooks of CPs for precision medicine are discussed. Through this systematic review, it is hoped to highlight the frontier progress of CPs and promote new breakthroughs in fundamental research and clinical transformation.

Nanoadjuvant-triggered STING activation evokes systemic immunotherapy for repetitive implant-related infections

Repetitive implant-related infections (IRIs) are devastating complications in orthopedic surgery, threatening implant survival and even the life of the host. Biofilms conceal bacterial-associated antigens (BAAs) and result in a "cold tumor"-like immune silent microenvironment, allowing the persistence of IRIs. To address this challenge, an iron-based covalent organic framed nanoadjuvant doped with curcumin and platinum (CFCP) was designed in the present study to achieve efficient treatment of IRIs by inducing a systemic immune response. Specifically, enhanced sonodynamic therapy (SDT) from CFCP combined with iron ion metabolic interference increased the release of bacterial-associated double-stranded DNA (dsDNA). Immunogenic dsDNA promoted dendritic cell (DC) maturation through activation of the stimulator of interferon gene (STING) and amplified the immune stimulation of neutrophils via interferon-β (IFN-β). At the same time, enhanced BAA presentation aroused humoral immunity in B and T cells, creating long-term resistance to repetitive infections. Encouragingly, CFCP served as neoadjuvant immunotherapy for sustained antibacterial protection on implants and was expected to guide clinical IRI treatment and relapse prevention.

A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment

Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near-infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface-enhanced Raman spectroscopy, near-infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Diagnostic Nanodevices.

Transpiration-Inspired Fabric Dressing for Acceleration Healing of Wound Infected with Biofilm

In chronic wound management, efficacious handling of exudate and bacterial infections stands as a paramount challenge. Here a novel biomimetic fabric, inspired by the natural transpiration mechanisms in plants, is introduced. Uniquely, the fabric combines a commercial polyethylene terephthalate (PET) fabric with asymmetrically grown 1D rutile titanium dioxide (TiO2) micro/nanostructures, emulating critical plant features: hierarchically porous networks and hydrophilic water conduction channels. This structure endows the fabric with exceptional antigravity wicking-evaporation performance, evidenced by a 780% one-way transport capability and a 0.75 g h-1 water evaporation rate, which significantly surpasses that of conventional moisture-wicking textiles. Moreover, the incorporated 1D rutile TiO2 micro/nanostructures present solar-light induced antibacterial activity, crucial for disrupting and eradicating wound biofilms. The biomimetic transpiration fabric is employed to drain exudate and eradicate biofilms in Staphylococcus aureus (S. aureus)-infected wounds, demonstrating a much faster infection eradication capability compared to clinically common ciprofloxacin irrigation. These findings illuminate the path for developing high-performance, textile-based wound dressings, offering efficient clinical platforms to combat biofilms associated with chronic wounds.

Recent progress in nanomaterials for bacteria-related tumor therapy

Many studies suggest that tumor microbiome closely relates to the oncogenesis and anti-tumor responses in multiple cancer types (e.g., colorectal cancer (CRC), breast cancer, lung cancer and pancreatic cancer), thereby raising an emerging research area of bacteria-related tumor therapy. Nanomaterials have long been used for both cancer and bacterial infection treatment, holding great potential for bacteria-related tumor therapy. In this review, we summarized recent progress in nanomaterials for bacteria-related tumor therapy. We focus on the types and mechanisms of pathogenic bacteria in the development and promotion of cancers and emphasize how nanomaterials work. We also briefly discuss the design principles and challenges of nanomaterials for bacteria-related tumor therapy. We hope this review can provide some insights into this emerging and rapidly growing research area.

Zinc Oxide-Based Nanomaterials for Microbiostatic Activities: A Review

The world is fighting infectious diseases. Therefore, effective antimicrobials are required to prevent the spread of microbes and protect human health. Zinc oxide (ZnO) nano-materials are known for their antimicrobial activities. Because of their distinctive physical and chemical characteristics, they can be used in medical and environmental applications. ZnO-based composites are among the leading sources of antimicrobial research. They are effective at killing (microbicidal) and inhibiting the growth (microbiostatic) of numerous microorganisms, such as bacteria, viruses, and fungi. Although most studies have focused on the microbicidal features, there is a lack of reviews on their microbiostatic effects. This review provides a detailed overview of available reports on the microbiostatic activities of ZnO-based nano-materials against different microorganisms. Additionally, the factors that affect the efficacy of these materials, their time course, and a comparison of the available antimicrobials are highlighted in this review. The basic properties of ZnO, challenges of working with microorganisms, and working mechanisms of microbiostatic activities are also examined. This review underscores the importance of further research to better understand ZnO-based nano-materials for controlling microbial growth.

A supramolecular hydrogel dressing with antibacterial, immunoregulation, and pro-regeneration ability for biofilm-associated wound healing

Chronic wound treatment has emerged as a significant healthcare concern worldwide due to its substantial economic burden and the limited effectiveness of current treatments. Effective management of biofilm infections, regulation of excessive oxidative stress, and promotion of tissue regeneration are crucial for addressing chronic wounds. Hydrogel stands out as a promising candidate for chronic wound treatment. However, its clinical application is hindered by the difficulty in designing and fabricating easily and conveniently. To overcome these obstacles, we present a supermolecular G-quadruplex hydrogel with the desired multifunction via a dynamic covalent strategy and Hoogsteen-type hydrogen bonding. The G-quadruplex hydrogel is made from the self-assembly of guanosine, 2-formylphenyboronic acid, polyethylenimine, and potassium chloride, employing dynamic covalent strategy and Hoogsteen-type hydrogen bonding. In the acidic/oxidative microenvironment associated with bacterial infections, the hydrogel undergoes controlled degradation, releasing the polyethylenimine domain, which effectively eliminates bacteria. Furthermore, nanocomplexes comprising guanosine monophosphate and manganese sulfate are incorporated into the hydrogel skeleton, endowing it with the ability to scavenge reactive oxygen species and modulate macrophages. Additionally, the integration of basic fibroblast growth factor into the G-quadruplex skeleton through dynamic covalent bonds facilitates controlled tissue regeneration. In summary, the facile preparation process and the incorporation of multiple functionalities render the G-quadruplex hydrogel a highly promising candidate for advanced wound dressing. It holds great potential to transition from laboratory research to clinical practice, addressing the pressing needs of chronic wound management.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research.

Polymer-DNA assembled nanoflower for targeted delivery of dolastatin-derived microtubule inhibitors

Dolastatin derivatives possess excellent anticancer activity and have been translated into clinical trials for cancer therapy. Drug delivery systems enable dolastatin derivatives to break the limitation of instability during blood circulation and ineffective cell internalization in the application. Nevertheless, their potential has not been thoroughly established because of the limited loading efficacy and complicated chemical modification. Herein, we rationally propose a rolling circle amplification-based polymer-DNA assembled nanoflower for targeted and efficient delivery of dolastatin-derived drugs to achieve efficient anticancer therapy. The polymer-DNA assembled nanoflower with targeted aptamer conjugate is widely applicable for loading dolastatin-derived drugs with high encapsulation efficiency. The developed monomethyl auristatin E (MMAE) loaded PN@M exhibited increased cellular uptake and enhanced inhibitory effect, especially in multidrug-resistant tumor cells. The results of in vivo anticancer effects indicate that nanoflower as a dolastatin derivatives delivery system holds considerable potential for the treatment of malignant cancer.

Disruption of Communication: Recent Advances in Antibiofilm Materials with Anti-Quorum Sensing Properties

Biofilm contamination presents a significant threat to public health, the food industry, and aquatic/marine-related applications. In recent decades, although various methods have emerged to combat biofilm contamination, the intricate and persistent nature of biofilms makes complete eradication challenging. Therefore, innovative alternative solutions are imperative for addressing biofilm formation. Instead of solely focusing on the eradication of mature biofilms, strategically advantageous measures involve the delay or prevention of biofilm formation on surfaces. Quorum sensing, a communication system enabling bacteria to coordinate their behavior based on population density, plays a pivotal role in biofilm formation for numerous microbial species. Materials possessing antibiofilm properties that target quorum sensing have gained considerable attention for their potential to prevent biofilm formation. This Review consolidates recent research progress on the utilization of materials with antiquorum sensing properties for combating biofilm formation. These materials can be categorized into three distinct types: (i) antibiofilm nanomaterials, (ii) antibiofilm surfaces, and (iii) antibiofilm hydrogels with antiquorum sensing capabilities. Finally, the Review concludes with a brief discussion of current challenges and outlines potential avenues for future research.

Bacteria-Targeting Nanoparticles with ROS-Responsive Antibiotic Release to Eradicate Biofilms and Drug-Resistant Bacteria in Endophthalmitis

Background

Bacterial endophthalmitis is an acute progressive visual threatening disease and one of the most important causes of blindness worldwide. Current treatments are unsatisfactory due to the emergence of drug-resistant bacteria and the formation of biofilm.

Purpose

The aim of our research was to construct a novel nano-delivery system with better antimicrobial and antibiofilm effects.

Methods

This study developed a novel antibiotic nanoparticle delivery system (MXF@UiO-UBI-PEGTK), which is composed of (i) moxifloxacin (MXF)-loaded UiO-66 nanoparticle as the core, (ii) bacteria-targeting peptide ubiquicidin (UBI29-41) immobilized on UiO-66, and (iii) ROS-responsive poly (ethylene glycol)-thioketal (PEG-TK) as the surface shell. Then the important properties of the newly developed delivery system, including biocompatibility, toxicity, release percentage, thermal stability, ability of targeting bacteria, and synergistic antibacterial effects on bacterial biofilms and endophthalmitis, were evaluated.

Results

In vitro, MXF@UiO-UBI-PEGTK exhibited significant antibiotic effects including the excellent antibiofilm property against Staphylococcus aureus, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus at high levels of ROS. Moreover, MXF@UiO-UBI-PEGTK demonstrated outstanding efficacy in treating bacterial endophthalmitis in vivo.

Conclusion

This novel nanoparticle delivery system with ROS-responsive and bacteria-targeted properties promotes the precise and effective release of drugs and has significant potential for clinical application of treating bacterial endophthalmitis.

H2O2 self-supplying and GSH-depleting nanosystem for amplified NIR mediated-chemodynamic therapy of MRSA biofilm-associated infections

Reactive oxygen species (ROS) has emerged as potent therapeutic agents for biofilm-associated bacterial infections. Chemodynamic therapy (CDT), involving the generation of high-energy ROS, displays great potential in the therapy of bacterial infections. However, challenges such as insufficient hydrogen peroxide (H2O2) and over-expressed glutathione (GSH) levels within the microenvironment of bacterial biofilms severely limit the antibacterial efficacy of CDT. Herein, we have developed a multifunctional nanoplatform (CuS@CaO2@Dex) by integrating copper sulfide (CuS) and calcium peroxide (CaO2) into dextran (Dex)-coated nanoparticles. This innovative platform enhanced ROS generation for highly efficient biofilm elimination by simultaneously supplying H2O2 and depleting GSH. The Dex-coating facilitated the penetrability of CuS@CaO2@Dex into biofilms, while CaO2 generated a substantial amount of H2O2 in the acidic biofilm microenvironment. CuS, through a Fenton-like reaction, catalyzed the conversion of self-supplied H2O2 into hydroxyl radicals (•OH) and consumed the overexpressed GSH. Additionally, the incorporation of near-infrared II (NIR II) laser irradiation enhanced the photothermal properties of CuS, improving the catalytic efficiency of the Fenton-like reaction for enhanced antibacterial effects. In vivo experiments have demonstrated that CuS@CaO2@Dex exhibited remarkable antibacterial and antibiofilm efficacy, exceptional wound healing capabilities, and notable biosafety. In summary, the Dex-coated nanoplatform proposed in this study, with its self-sterilization capability through ROS, holds significant potential for future biomedical applications.

Recent Advances in Antibacterial Coatings to Combat Orthopedic Implant-Associated Infections

Implant-associated infections (IAIs) represent a major health burden due to the complex structural features of biofilms and their inherent tolerance to antimicrobial agents and the immune system. Thus, the viable options to eradicate biofilms embedded on medical implants are surgical operations and long-term and repeated antibiotic courses. Recent years have witnessed a growing interest in the development of robust and reliable strategies for prevention and treatment of IAIs. In particular, it seems promising to develop materials with anti-biofouling and antibacterial properties for combating IAIs on implants. In this contribution, we exclusively focus on recent advances in the development of modified and functionalized implant surfaces for inhibiting bacterial attachment and eventually biofilm formation on orthopedic implants. Further, we highlight recent progress in the development of antibacterial coatings (including self-assembled nanocoatings) for preventing biofilm formation on orthopedic implants. Among the recently introduced approaches for development of efficient and durable antibacterial coatings, we focus on the use of safe and biocompatible materials with excellent antibacterial activities for local delivery of combinatorial antimicrobial agents for preventing and treating IAIs and overcoming antimicrobial resistance.

Strategies to Promote the Journey of Nanoparticles Against Biofilm-Associated Infections

Biofilm-associated infections are one of the most challenging healthcare threats for humans, accounting for 80% of bacterial infections, leading to persistent and chronic infections. The conventional antibiotics still face their dilemma of poor therapeutic effects due to the high tolerance and resistance led by bacterial biofilm barriers. Nanotechnology-based antimicrobials, nanoparticles (NPs), are paid attention extensively and considered as promising alternative. This review focuses on the whole journey of NPs against biofilm-associated infections, and to clarify it clearly, the journey is divided into four processes in sequence as 1) Targeting biofilms, 2) Penetrating biofilm barrier, 3) Attaching to bacterial cells, and 4) Translocating through bacterial cell envelope. Through outlining the compositions and properties of biofilms and bacteria cells, recent advances and present the strategies of each process are comprehensively discussed to combat biofilm-associated infections, as well as the combined strategies against these infections with drug resistance, aiming to guide the rational design and facilitate wide application of NPs in biofilm-associated infections.

Zein nanoparticles containing ceftazidime and tobramycin: antibacterial activity against Gram-negative bacteria

Aims: This work describes the encapsulation of ceftazidime and tobramycin in zein nanoparticles (ZNPs) and the characterization of their antibacterial and antibiofilm activities against Gram-negative bacteria. Materials & methods: ZNPs were synthesized by nanoprecipitation. Cytotoxicity was assessed by MTT assay and antibacterial and antibiofilm assays were performed by broth microdilution and violet crystal techniques. Results: ZNPs containing ceftazidime (CAZ-ZNPs) and tobramycin (TOB-ZNPs) showed drug encapsulation and thermal stability. Encapsulation of the drugs reduced their cytotoxicity 9-25-fold. Antibacterial activity, inhibition and eradication of biofilm by CAZ-ZNPs and TOB-ZNPs were observed. There was potentiation when CAZ-ZNPs and TOB-ZNPs were combined. Conclusion: CAZ-ZNPs and TOB-ZNPs present ideal physical characteristics for in vivo studies of antibacterial and antibiofilm activities.

Polylactic Glycolic Acid-Mediated Delivery of Plectasin Derivative NZ2114 in Staphylococcus epidermidis Biofilms

Antimicrobial peptides (AMPs) are antibiotic candidates; however, their instability and protease susceptibility limit clinical applications. In this study, the polylactic acid-glycolic acid (PLGA)-polyvinyl alcohol (PVA) drug delivery system was screened by orthogonal design using the double emulsion-solvent evaporation method. NZ2114 nanoparticles (NZ2114-NPs) displayed favorable physicochemical properties with a particle size of 178.11 ± 5.23 nm, polydispersity index (PDI) of 0.108 ± 0.10, ζ potential of 4.78 ± 0.67 mV, actual drug-loading rate of 4.07 ± 0.37%, encapsulation rate of 81.46 ± 7.42% and cumulative release rate of 67.75% (120 h) in PBS. The results showed that PLGA encapsulation increased HaCaT cell viability by 20%, peptide retention in 50% serum by 24.12%, and trypsin tolerance by 4.24-fold. Meanwhile, in vitro antimicrobial assays showed that NZ2114-NPs had high inhibitory activity against Staphylococcus epidermidis (S. epidermidis) (4-8 μg/mL). Colony counting and confocal laser scanning microscopy (CLSM) confirmed that NZ2114-NPs were effective in reducing the biofilm thickness and bacterial population of S. epidermidis G4 with a 99% bactericidal rate of persister bacteria, which was significantly better than that of free NZ2114. In conclusion, the results demonstrated that PLGA nanoparticles can be used as a reliable NZ2114 delivery system for the treatment of biofilm infections caused by S. epidermidis.

Quaternary ammonium-tethered hyperbranched polyurea nanoassembly synergized with antibiotics for enhanced antimicrobial efficacy

The effective transportation of antibiotics to bacteria embedded within a biofilm consisting of a dense matrix of extracellular polymeric substances is still a challenge in the treatment of bacterial biofilm associated infections. Here, we developed an antibiotic nanocarrier constructed from quaternary ammonium-tethered hyperbranched polyureas (HPUs-QA), which showed high loading capacity for a model antibiotic, rifampicin, and high efficacy in the transportation of rifampicin to biofilms. The rifampicin-loaded HPUs-QA nanoassembly (HPUs-Rif/QA) demonstrated a synergistic antimicrobial effect in killing planktonic bacteria and eradicating the corresponding biofilms. Compared to the treatment of bacteria-infected chronic wounds by either HPUs-QA or rifampicin alone, HPUs-Rif/QA showed superior efficacy in promoting wound healing by more effectively inhibiting bacteria colonization. This study highlights the potential of the HPUs-QA nanoassembly in synergistic action with antibiotics for the treatment of biofilm associated infections.

Activity of biogenic silver nanoparticles in planktonic and biofilm-associated Corynebacterium pseudotuberculosis

Corynebacterium pseudotuberculosis is a gram-positive bacterium and is the etiologic agent of caseous lymphadenitis (CL) in small ruminants. This disease is characterized by the development of encapsulated granulomas in visceral and superficial lymph nodes, and its clinical treatment is refractory to antibiotic therapy. An important virulence factor of the Corynebacterium genus is the ability to produce biofilm; however, little is known about the characteristics of the biofilm produced by C. pseudotuberculosis and its resistance to antimicrobials. Silver nanoparticles (AgNPs) are considered as promising antimicrobial agents, and are known to have several advantages, such as a broad-spectrum activity, low resistance induction potential, and antibiofilm activity. Therefore, we evaluate herein the activity of AgNPs in C. pseudotuberculosis, through the determination of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antibiofilm activity, and visualization of AgNP-treated and AgNP-untreated biofilm through scanning electron microscopy. The AgNPs were able to completely inhibit bacterial growth and inactivate C. pseudotuberculosis at concentrations ranging from 0.08 to 0.312 mg/mL. The AgNPs reduced the formation of biofilm in reference strains and clinical isolates of C. pseudotuberculosis, with interference values greater than 80% at a concentration of 4 mg/mL, controlling the change between the planktonic and biofilm-associated forms, and preventing fixation and colonization. Scanning electron microscopy images showed a significant disruptive activity of AgNP on the consolidated biofilms. The results of this study demonstrate the potential of AgNPs as an effective therapeutic agent against CL.

Ciprofloxacin Poly(β-amino ester) Conjugates Enhance Antibiofilm Activity and Slow the Development of Resistance

To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial biofilms are a particular concern in this context as they are responsible for over 80% of bacterial infections and are inherently more recalcitrant toward antimicrobial treatments. The high tolerance of biofilms to conventional antibiotics has been attributed to several factors, including reduced drug diffusion through the dense exopolymeric matrix and the upregulation of antimicrobial resistance machinery with successful biofilm eradication requiring prolonged high doses of multidrug treatments. A promising approach to tackle bacterial infections involves the use of polymer drug conjugates, shown to improve upon free drug toxicity and bioavailability, enhance drug penetration through the thick biofilm matrix, and evade common resistance mechanisms. In the following study, we conjugated the antibiotic ciprofloxacin (CIP) to a small library of biodegradable and biocompatible poly(β-amino ester) (PBAE) polymers with varying central amine functionality. The suitability of the polymers as antibiotic conjugates was then verified in a series of assays including testing of efficacy and resistance response in planktonic Gram-positive and Gram-negative bacteria and the reduction of viability in mono- and multispecies biofilm models. The most active polymer within the prepared PBAE-CIP library was shown to achieve an over 2-fold increase in the reduction of biofilm viability in a Pseudomonas aeruginosa monospecies biofilm and superior elimination of all the species present within the multispecies biofilm model. Hence, we demonstrate that CIP conjugation to PBAEs can be employed to achieve improved antibiotic efficacy against clinically relevant biofilm models.

Nano-Bio Interactions: Biofilm-Targeted Antibacterial Nanomaterials

Biofilm is a spatially organized community formed by the accumulation of both microorganisms and their secretions, leading to persistent and chronic infections because of high resistance toward conventional antibiotics. In view of the tunable physicochemical properties and the related unique biological behavior (e.g., size-, shape-, and surface charge-dependent penetration, protein corona endowed targeting, catalytic- and electronic-related oxidative stress, optical- and magnetic-associated hyperthermia, etc.), nanomaterials-based therapeutics are widely used for the treatment of biofilm-associated infections. In this review, the biological characteristics of biofilm are introduced. And the nanomaterials-based antibacterial strategies are further discussed via biofilm targeting, including preventing biofilm formation, enhancing biofilm penetration, disrupting the mature biofilm, and acting as drug delivery systems. In which, the interactions between biofilm and nanomaterials include mechanical disruption, electron transfer, enzymatic degradation, oxidative stress, and hyperthermia. Additionally, the current advances of nanomaterials for antibacterial nanomaterials by biofilm targeting are summarized. This review aims to present a complete vision of antibacterial nanomaterials-biofilm (nano-bio) interactions, paving the way for the future development and clinical translation of effective antibacterial nanomedicines.

Drug-loaded lipid nanoparticles improve the removal rates of the Staphylococcus aureus biofilm

Biofilms of the foodborne pathogen Staphylococcus aureus show improved resistance to antibiotics and are difficult to eliminate. To enhance antibacteria and biofilm dispersion via extracellular matrix diffusion, a new lipid nanoparticle was prepared, which employed a mixture of phospholipids and a 0.8% surfactin shell. In the lipid nanoparticle, 31.56 μg mL-1 of erythromycin was encapsulated. The lipid nanoparticle size was approximately 52 nm and the zeta-potential was -67 mV, which was measured using a Marvin laser particle size analyzer. In addition, lipid nanoparticles significantly dispersed the biofilms of S. aureus W1, CICC22942, and CICC 10788 on the surface of stainless steel, reducing the total viable count of bacteria in the biofilms by 103 CFU mL-1 . In addition, the lipid nanoparticle can remove polysaccharides and protein components from the biofilm matrix. The results of laser confocal microscopy showed that the lipid nanoparticles effectively killed residual bacteria in the biofilms. Thus, to thoroughly eliminate biofilms on material surfaces in food factories to avoid repeated contamination, drug-lipid nanoparticles present a suitable method to achieve this.

Engineering Antimicrobial Metal-Phenolic Network Nanoparticles with High Biocompatibility for Wound Healing

Antibiotic-resistant bacteria pose a global health threat by causing persistent and recurrent microbial infections. To address this issue, antimicrobial nanoparticles (NPs) with low drug resistance but potent bactericidal effects have been developed. However, many of the developed NPs display poor biosafety and their synthesis often involves complex procedures and the antimicrobial modes of action are unclear. Herein, a simple strategy is reported for designing antimicrobial metal-phenolic network (am-MPN) NPs through the one-step assembly of a seeding agent (diethyldithiocarbamate), natural polyphenols, and metal ions (e.g., Cu2+ ) in aqueous solution. The Cu2+ -based am-MPN NPs display lower Cu2+ antimicrobial concentrations (by 10-1000 times) lower than most reported nanomaterials and negligible toxicity across various models, including, cells, blood, zebrafish, and mice. Multiple antimicrobial modes of the NPs have been identified, including bacterial wall disruption, reactive oxygen species production, and quinoprotein formation, with the latter being a distinct pathway identified for the antimicrobial activity of the polyphenol-based am-MPN NPs. The NPs exhibit excellent performance against multidrug-resistant bacteria (e.g., methicillin-resistant Staphylococcus aureus (MRSA)), efficiently inhibit and destroy bacterial biofilms, and promote the healing of MRSA-infected skin wounds. This study provides insights on the antimicrobial properties of metal-phenolic materials and the rational design of antimicrobial metal-organic materials.

Metal-Phenolic Network with Pd Nanoparticle Nodes Synergizes Oxidase-Like and Photothermal Properties to Eradicate Oral Polymicrobial Biofilm-Associated Infections

Designing an effective treatment strategy to combat oral diseases caused by complex polymicrobial biofilms remains a great challenge. Herein, a series of metal-phenolic network with Pd nanoparticle nodes using polyphenols as stabilizers and reducing agents is constructed. Among them, sulfonated lignin-Pd (SLS-Pd) with ultrafine size palladium nanoparticles and broadband near infrared absorption exhibit excellent oxidase-like activity and stable photothermal effect. In vitro experiments demonstrate that the superoxide radical generated by SLS-Pd oxidase-like activity exhibits selective antibacterial effects, while its photothermal effect induced hyperthermia exhibits potent antifungal properties. This difference is further elucidated by RNA-sequencing analysis and all-atom simulation. Moreover, the SLS-Pd-mediated synergistic antimicrobial system exhibits remarkable efficacy in combating various biofilms and polymicrobial biofilms. By establishing a root canal model and an oropharyngeal candidiasis model, the feasibility of the synergistic antimicrobial system in treating oral biofilm-related infections is further validated. This system provides a promising therapeutic approach for polymicrobial biofilm-associated infections in the oral cavity.

Infiltrating Perfluorocarbon Nanoemulsion and Sensitizing Ultrasound Cavitation to Eradicate Biofilms

Developing strategies for the treatment of bacterial biofilms is challenging due to their complex and resilient structure, low permeability to therapeutics, and ability to protect resident pathogens. Herein, we demonstrate that a polylysine-stabilized perfluorocarbon nanoemulsion is favored for penetrating biofilms and sensitizing the cavitation effect of low-intensity ultrasound, resulting in the dispersal of extracellular polymeric substances and killing of the protected cells. Through experiments, we observed a complete penetration of the nanoemulsion in a 40 μm Pseudomonas aeruginosa biofilm and demonstrated that it was induced by the fluidic perfluorocarbon, possibly attributing to its low surface tension. Furthermore, we presented an almost complete antibiofilm effect with a low-intensity ultrasound (1 MHz, 0.75 W/cm2, 5 min) in diverse cases, including cultured biofilms, colonized urinary catheters, and chronic wounds. During the treatment process, the perfluorocarbon phase enhanced the number and imploding energy of ultrasound cavities, thoroughly divided the biofilm structure, prevented biofilm self-healing, and sterilized the resident pathogens. Thus, the penetration and sensitization of the nanoemulsion might serve as a facile and potent strategy for eradicating biofilms in various applications.