Stimuli-responsive nanocarriers for bacterial biofilm treatment

Engineering dynamic covalent bond-based nanosystems for delivery of antimicrobials against bacterial infections

Nanodrug delivery systems (NDDS) continue to be explored as novel strategies enhance therapy outcomes and combat microbial resistance. The need for the formulation of smart drug delivery systems for targeting infection sites calls for the engineering of responsive chemical designs such as dynamic covalent bonds (DCBs). Stimuli response due to DCBs incorporated into nanosystems are emerging as an alternative way to target infection sites, thus enhancing the delivery of antibacterial agents. This leads to the eradication of bacterial infections and the reduction of antimicrobial resistance. Incorporating DCBs on the backbone of the nanoparticles endows the systems with several properties, including self-healing, controlled disassembly, and stimuli responsiveness, which are beneficial in the delivery and release of the antimicrobial at the infection site. This review provides a comprehensive and current overview of conventional DCBs-based nanosystems, stimuli-responsive DCBs-based nanosystems, and targeted DCBs-based nanosystems that have been reported in the literature for antibacterial delivery. The review emphasizes the DCBs used in their design, the nanomaterials constructed, the drug release-triggering stimuli, and the antibacterial efficacy of the reported DCBs-based nanosystems. Additionally, the review underlines future strategies that can be used to improve the potential of DCBs-based nanosystems to treat bacterial infections and overcome antibacterial resistance.

Nanocomposite hyaluronic acid adhesive hydrogel with controllable drug release for bone regeneration

Hyaluronic acid (HA) hydrogels have arisen as candidate materials to simulate the extracellular matrix and restore the functions of both cartilage and hard bones. However, integration of bone tissue adhesion and long-term osteogenic properties in one hydrogel is often ignored. Herein, a strategy to construct nanocomposite hydrogel with host tissue adhesive properties, enhanced mechanical strength, improved stability and osteogenic effects was developed. Simvastatin (SIM) was firstly incorporated into zeolitic imidazolate framework-8 (ZIF-8) and surface decoration with hydroxyapatite was realized to obtain SIM loaded and hydroxyapatite modified ZIF-8 particles (SP). As the inorganic strengthening component, SP could further cross-link the mixture of dopamine-hyaluronic acid (dHA) and tannic (TA) via coordination interaction to fabricate the hybrid adhesive hydrogel (dHA/TA/SP). Sufficient phenolic groups endowed dHA/TA/SP with excellent tissue adhesion and antibacterial properties, while incorporation of SP significantly improved the mechanical strength and stability of hydrogel. Further, due to the multiple protective effects of ZIF-8 and hydrogel, SIM was sustainably released from dHA/TA/SP. Together with the active Zn2+ and Ca2+, the expressions of ALP, OCN and RUNX2 were upregulated, and the mineralization was also promoted. With significant osteogenic effect in vitro and in vivo, this nanocomposite adhesive hydrogel holds great potential for bone defects repair.

Application of biofilm dispersion-based nanoparticles in cutting off reinfection

Bacterial biofilms commonly cause chronic and persistent infections in humans. Bacterial biofilms consist of an inner layer of bacteria and an autocrine extracellular polymeric substance (EPS). Biofilm dispersants (abbreviated as dispersants) have proven effective in removing the bacterial physical protection barrier EPS. Dispersants are generally weak or have no bactericidal effect. Bacteria dispersed from within biofilms (abbreviated as dispersed bacteria) may be more invasive, adhesive, and motile than planktonic bacteria, characteristics that increase the probability that dispersed bacteria will recolonize and cause reinfection. The dispersants should be combined with antimicrobials to avoid the risk of severe reinfection. Dispersant-based nanoparticles have the advantage of specific release and intense penetration, providing the prerequisite for further antibacterial agent efficacy and achieving the eradication of biofilms. Dispersant-based nanoparticles delivered antimicrobial agents for the treatment of diseases associated with bacterial biofilm infections are expected to be an effective measure to prevent reinfection caused by dispersed bacteria. KEY POINTS: • Dispersed bacteria harm and the dispersant's dispersion mechanisms are discussed. • The advantages of dispersant-based nanoparticles in bacteria biofilms are discussed. • Dispersant-based nanoparticles for cutting off reinfection in vivo are highlighted.

Unveiling innovative therapeutic strategies and future trajectories on stimuli-responsive drug delivery systems for targeted treatment of breast carcinoma

This comprehensive review delineates the latest advancements in stimuli-responsive drug delivery systems engineered for the targeted treatment of breast carcinoma. The manuscript commences by introducing mammary carcinoma and the current therapeutic methodologies, underscoring the urgency for innovative therapeutic strategies. Subsequently, it elucidates the logic behind the employment of stimuli-responsive drug delivery systems, which promise targeted drug administration and the minimization of adverse reactions. The review proffers an in-depth analysis of diverse types of stimuli-responsive systems, including thermoresponsive, pH-responsive, and enzyme-responsive nanocarriers. The paramount importance of material choice, biocompatibility, and drug loading strategies in the design of these systems is accentuated. The review explores characterization methodologies for stimuli-responsive nanocarriers and probes preclinical evaluations of their efficacy, toxicity, pharmacokinetics, and biodistribution in mammary carcinoma models. Clinical applications of stimuli-responsive systems, ongoing clinical trials, the potential of combination therapies, and the utility of multifunctional nanocarriers for the co-delivery of assorted drugs and therapies are also discussed. The manuscript addresses the persistent challenge of drug resistance in mammary carcinoma and the potential of stimuli-responsive systems in surmounting it. Regulatory and safety considerations, including FDA guidelines and biocompatibility assessments, are outlined. The review concludes by spotlighting future trajectories and emergent technologies in stimuli-responsive drug delivery, focusing on pioneering approaches, advancements in nanotechnology, and personalized medicine considerations. This review aims to serve as a valuable compendium for researchers and clinicians interested in the development of efficacious and safe stimuli-responsive drug delivery systems for the treatment of breast carcinoma.

Liposomal drug delivery strategies to eradicate bacterial biofilms: Challenges, recent advances, and future perspectives

Typical antibiotic treatments are often ineffectual against biofilm-related infections since bacteria residing within biofilms have developed various mechanisms to resist antibiotics. To overcome these limitations, antimicrobial-loaded liposomal nanoparticles are a promising anti-biofilm strategy as they have demonstrated improved antibiotic delivery and eradication of bacteria residing in biofilms. Antibiotic-loaded liposomal nanoparticles revealed remarkably higher antibacterial and anti-biofilm activities than free drugs in experimental settings. Moreover, liposomal nanoparticles can be used efficaciously for the combinational delivery of antibiotics and other antimicrobial compounds/peptide which facilitate, for instance, significant breakdown of the biofilm matrix, increased bacterial elimination from biofilms and depletion of metabolic activity of various pathogens. Drug-loaded liposomes have mitigated recurrent infections and are considered a promising tool to address challenges associated to antibiotic resistance. Furthermore, it has been demonstrated that surface charge and polyethylene glycol modification of liposomes have a notable impact on their antibacterial biofilm activity. Future investigations should tackle the persistent hurdles associated with development of safe and effective liposomes for clinical application and investigate novel antibacterial treatments, including CRISPR-Cas gene editing, natural compounds, phages, and nano-mediated approaches. Herein, we emphasize the significance of liposomes in inhibition and eradication of various bacterial biofilms, their challenges, recent advances, and future perspectives.

Anti-adhesion multifunctional poly(lactic-co-glycolic acid)/polydimethylsiloxane wound dressing for bacterial infection monitoring and photodynamic antimicrobial therapy

Wound infection and adhesion are important factors affecting wound healing. Early detection of pathogen infection and reduction of wound-to-dressing adhesion are critical for improving wound healing. Herein, Ester-J, which can rapidly respond to lipase secreted by bacteria, was designed and synthesized. Then, Ester-J was co-spun with poly(lactic-co-glycolic acid) (PLGA) and polydimethylsiloxane (PDMS) to prepare a PP-EsJ hydrophobic anti-adhesion dressing with a contact angle of 140.7°. When the PP-EsJ membrane came into contact with the bacteria, the loaded Ester-J was hydrolyzed to Tph-TSF-OH, releasing bright cyan-blue fluorescence, thus providing a fluorescence switch for an early warning of infection. The detection limits of PP-EsJ for Pseudomonas aeruginosa and Staphylococcus aureus were 1.0 × 105 and 1.0 × 106 CFU/mL, respectively. Subsequently, Tph-TSF-OH released 1O2 through light irradiation, which rapidly killed P. aeruginosa and S. aureus, and accelerated wound healing. Compared with the control group, enhanced wound closure (up to 99.80 ± 1.10 %) was observed in mice treated with the PP-EsJ membrane. The PP-EsJ membrane not only effectively reduced the risk of external infection but also reduced adhesions to the skin during dressing changes. These characteristics make PP-EsJ membranes potentially useful for clinical treatment.

Recent advances in metal-organic frameworks for stimuli-responsive drug delivery

After entering the human body, drugs for treating diseases, which are prone to delivery and release in an uncontrolled manner, are affected by various factors. Based on this, many researchers utilize various microenvironmental changes encountered during drug delivery to trigger drug release and have proposed stimuli-responsive drug delivery systems. In recent years, metal-organic frameworks (MOFs) have become promising stimuli-responsive agents to release the loaded therapeutic agents at the target site to achieve more precise drug delivery due to their high drug loading, excellent biocompatibility, and high stimuli-responsiveness. The MOF-based stimuli-responsive systems can respond to various stimuli under pathological conditions at the site of the lesion, releasing the loaded therapeutic agent in a controlled manner, and improving the accuracy and safety of drug delivery. Due to the changes in different physical and chemical factors in the pathological process of diseases, the construction of stimuli-responsive systems based on MOFs has become a new direction in drug delivery and controlled release. Based on the background of the rapidly increasing attention to MOFs applied in drug delivery, we aim to review various MOF-based stimuli-responsive drug delivery systems and their response mechanisms to various stimuli. In addition, the current challenges and future perspectives of MOF-based stimuli-responsive drug delivery systems are also discussed in this review.

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.

Heparin-network-mediated long-lasting coatings on intravascular catheters for adaptive antithrombosis and antibacterial infection

Bacteria-associated infections and thrombosis, particularly catheter-related bloodstream infections and catheter-related thrombosis, are life-threatening complications. Herein, we utilize a concise assembly of heparin sodium with organosilicon quaternary ammonium surfactant to fabricate a multifunctional coating complex. In contrast to conventional one-time coatings, the complex attaches to medical devices with arbitrary shapes and compositions through a facile dipping process and further forms robust coatings to treat catheter-related bloodstream infections and thrombosis simultaneously. Through their robustness and adaptively dissociation, coatings not only exhibit good stability under extreme conditions but also significantly reduce thrombus adhesion by 60%, and shows broad-spectrum antibacterial activity ( > 97%) in vitro and in vivo. Furthermore, an ex vivo rabbit model verifies that the coated catheter has the potential to prevent catheter-related bacteremia during implantation. This substrate-independent and portable long-lasting multifunctional coating can be employed to meet the increasing clinical demands for combating catheter-related bloodstream infections and thrombosis.

Type I Photosensitizer Targeting Glycans: Overcoming Biofilm Resistance by Inhibiting the Two-Component System, Quorum Sensing, and Multidrug Efflux

Stubborn biofilm infections pose serious threats to human health due to the persistence, recurrence, and dramatically magnified antibiotic resistance. Photodynamic therapy has emerged as a promising approach to combat biofilm. Nevertheless, how to inhibit the bacterial signal transduction system and the efflux pump to conquer biofilm recurrence and resistance remains a challenging and unaddressed issue. Herein, a boric acid-functionalized lipophilic cationic type I photosensitizer, ACR-DMP, is developed, which efficiently generates •OH to overcome the hypoxic microenvironment and photodynamically eradicates methicillin-resistant Staphylococcus aureus (MRSA) and biofilms. Furthermore, it not only alters membrane potential homeostasis and osmotic pressure balance due to its strong binding ability with plasma membrane but also inhibits quorum sensing and the two-component system, reduces virulence factors, and regulates the activity of the drug efflux pump attributed to the glycan-targeting ability, helping to prevent biofilm recurrence and conquer biofilm resistance. In vivo, ACR-DMP successfully obliterates MRSA biofilms attached to implanted medical catheters, alleviates inflammation, and promotes vascularization, thereby combating infections and accelerating wound healing. This work not only provides an efficient strategy to combat stubborn biofilm infections and bacterial multidrug resistance but also offers systematic guidance for the rational design of next-generation advanced antimicrobial materials.

Attenuation of biofilm and quorum sensing regulated virulence factors of an opportunistic pathogen Pseudomonas aeruginosa by phytofabricated silver nanoparticles

Green-synthesized nanoparticles provide an effective strategy for inhibiting microbial pathogenesis by affecting biofilm formation, quorum sensing (QS), and other surface properties of microorganisms. QS is a density-dependent communication signaling cascade that regulates biofilm formation and other pathogenic factors of Pseudomonas aeruginosa. In this context, the effect of phytofabricated silver nanoparticles (CC-AgNPs) synthesized using Cuphea carthagenensis extract on biofilm, QS, and QS-dependent virulence factors of P. aeruginosa were evaluated in this study. CC-AgNPs demonstrated significant attenuation of biofilm, QS, and QS-dependent virulence factors at sub-MICs. A significant inhibition of 88.39 ± 4.32 %, 79.64 ± 3.31 %, 73.07 ± 3.0 %, and 61.67 ± 1.5 % of biofilm formation, quorum sensing, pyocyanin, and LasB elastase, respectively was reported in the study at 20 μg/mL. The study also demonstrated a significant reduction of LasA Staphylolytic activity and 91.37 ± 1.05 % exoprotease production in comparison to untreated control. The lower concentrations of CC-AgNPs also demonstrated significant attenuation of biofilm and other virulence factors suggesting the strong potency of NPs against P. aeruginosa. XTT analysis reported the effect of CC-AgNPs on sessile cells of P. aeruginosa without impacting growth of planktonic cells at sub-MICs. Cell-proliferation study in human cell lines (HEK 293 and Caco-2 cells) demonstrated the safe nature of CC-AgNPs at tested concentrations. This study is novel in a way that environmentally friendly CC-AgNPs were used to inhibit QS at sub-MICs without killing the tested strains, therefore, could be developed as an anti-virulent drug to overcome biofilm and antimicrobial resistance problems.

Polyzwitterionic micelles with antimicrobial-conjugation for eradication of drug-resistant bacterial biofilms

The presence of bacterial biofilms has presented a significant challenge to human health. This study presents the development of biofilm microenvironment-responsive polymeric micelles as a novel approach to address the challenges posed by bacterial biofilms. These micelles are composed of two key components: a zwitterionic component, inspired by protein isoelectric points, containing balanced quantities of primary amines and carboxylic groups that undergo a positive charge transformation in acidic microenvironments, and a hydrophobic triclosan conjugate capable of releasing triclosan in the presence of bacterial lipases. Through the synergistic combination of pH-responsiveness and lipase-responsiveness, we have significantly improved drug penetration into biofilms and enhanced its efficacy in killing bacteria. With their remarkable drug-loading capacity and the ability to specifically target and eliminate bacteria within biofilms, these zwitterionic polymeric micelles hold great promise as an effective alternative for treating biofilm-associated infections. Their unique properties enable efficient drug delivery and heightened effectiveness against biofilm-related infections.

Water-Triggered Segment Orientation of Long-Lasting Anti-Biofouling Polyurethane Coatings on Biomedical Catheters via Solvent Exchange Strategy

The formation of biofilm and thrombus on medical catheters poses a significant life-threatening concern. Hydrophilic anti-biofouling coatings upon catheter surfaces with complex shapes and narrow lumens are demonstrated to have the potential in reducing complications. However, their effectiveness is constrained by poor mechanical stability and weak substrate adhesion. Herein, a novel zwitterionic polyurethane (SUPU) with strong mechanical stability and long-term anti-biofouling is developed by controlling the ratio of sulfobetaine-diol and ureido-pyrimidinone. Once immersed in water, as-synthesized zwitterionic coating (SUPU3 SE) would undergo a water-driven segment reorientation to obtain much higher durability than its direct drying one, even under various extreme treatments, including acidic solution, abrasion, ultrasonication, flushing, and shearing, in PBS at 37 °C for 14 days. Moreover, SUPU3 SE coating could achieve a 97.1% of exceptional reducing protein fouling, complete prevention of cell adhesion, and long-lasting anti-biofilm performance even after 30 days. Finally, the good anti-thrombogenic formations of SUPU3 SE coating with bacterial treatment are validated in blood circulation through an ex vivo rabbit arteriovenous shunt model. This work provides a facile approach to fabricating stable hydrophilic coating through a simple solvent exchange to reduce thrombosis and infection of biomedical catheters.

Nanobiotics and the One Health Approach: Boosting the Fight against Antimicrobial Resistance at the Nanoscale

Antimicrobial resistance (AMR) is a growing public health concern worldwide, and it poses a significant threat to human, animal, and environmental health. The overuse and misuse of antibiotics have contributed significantly and others factors including gene mutation, bacteria living in biofilms, and enzymatic degradation/hydrolyses help in the emergence and spread of AMR, which may lead to significant economic consequences such as reduced productivity and increased health care costs. Nanotechnology offers a promising platform for addressing this challenge. Nanoparticles have unique properties that make them highly effective in combating bacterial infections by inhibiting the growth and survival of multi-drug-resistant bacteria in three areas of health: human, animal, and environmental. To conduct an economic evaluation of surveillance in this context, it is crucial to obtain an understanding of the connections to be addressed by several nations by implementing national action policies based on the One Health strategy. This review provides an overview of the progress made thus far and presents potential future directions to optimize the impact of nanobiotics on AMR.

Liposomes-Based Drug Delivery Systems of Anti-Biofilm Agents to Combat Bacterial Biofilm Formation

All currently approved antibiotics are being met by some degree of resistance by the bacteria they target. Biofilm formation is one of the crucial enablers of bacterial resistance, making it an important bacterial process to target for overcoming antibiotic resistance. Accordingly, several drug delivery systems that target biofilm formation have been developed. One of these systems is based on lipid-based nanocarriers (liposomes), which have shown strong efficacy against biofilms of bacterial pathogens. Liposomes come in various types, namely conventional (charged or neutral), stimuli-responsive, deformable, targeted, and stealth. This paper reviews studies employing liposomal formulations against biofilms of medically salient gram-negative and gram-positive bacterial species reported recently. When it comes to gram-negative species, liposomal formulations of various types were reported to be efficacious against Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and members of the genera Klebsiella, Salmonella, Aeromonas, Serratia, Porphyromonas, and Prevotella. A range of liposomal formulations were also effective against gram-positive biofilms, including mostly biofilms of Staphylococcal strains, namely Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus subspecies bovis, followed by Streptococcal strains (pneumonia, oralis, and mutans), Cutibacterium acnes, Bacillus subtilis, Mycobacterium avium, Mycobacterium avium subsp. hominissuis, Mycobacterium abscessus, and Listeria monocytogenes biofilms. This review outlines the benefits and limitations of using liposomal formulations as means to combat different multidrug-resistant bacteria, urging the investigation of the effects of bacterial gram-stain on liposomal efficiency and the inclusion of pathogenic bacterial strains previously unstudied.

Nanoparticle-mediated stimulus-responsive antibacterial therapy

The limitations associated with conventional antibacterial therapies and the subsequent amplification of multidrug-resistant (MDR) microorganisms have increased, necessitating the urgent development of innovative antibacterial techniques. Accordingly, nanoparticle-mediated therapeutics have emerged as potential candidates for antibacterial treatment due to their suitable dimensions, penetration capacity, and high efficiency in targeted drug delivery. However, although nanoparticle-based drug delivery systems have been demonstrated to be effective, they are limited by their overuse and unwanted side effects. Thus, to overcome these drawbacks, stimulus-responsive antibiotic delivery has been extended as a promising strategy for site-specific restricted drug exemption. Nano-formulations that are triggered by various stimuli, such as intrinsic, extrinsic, and bacterial stimuli, have been developed. Thus, by harnessing the physicochemical properties of various nanoparticles, the selective release of therapeutic cargoes can be achieved through the application of a variety of local stimuli such as light, sound, irradiation, pH, and magnetic field. In this review, we also highlight the progress and perspectives of stimulus-responsive combination therapy, with special emphasis on the eradication of MDR strains and biofilms. Hence, this review addresses the advancement and challenges in the applications of stimulus-responsive nanoparticles together with the various future prospects of this technique.

In silico and in vitro studies of GENT-EDTA encapsulated niosomes: A novel approach to enhance the antibacterial activity and biofilm inhibition in drug-resistant Klebsiella pneumoniae

Klebsiella pneumoniae (Kp) is a common pathogen inducing catheter-related biofilm infections. Developing effective therapy to overcome antimicrobial resistance (AMR) in Kp is a severe therapeutic challenge that must be solved. This study aimed to prepare niosome-encapsulated GENT (Gentamicin) and EDTA (Ethylenediaminetetraacetic acid) (GENT-EDTA/Nio) to evaluate its efficacy toward Kp strains. The thin-film hydration method was used to prepare various formulations of GENT-EDTA/Nio. Formulations were characterized for their physicochemical characteristics. GENT-EDTA/Nio properties were used for optimization with Design-Expert Software. Molecular docking was utilized to determine the antibacterial activity of GENT. The niosomes displayed a controlled drug release and storage stability of at least 60 days at 4 and 25 °C. GENT-EDTA/Nio performance as antimicrobial agents has been evaluated by employing agar well diffusion method, minimum bactericidal concentration (MBC), and minimum inhibitory concentration (MIC) against the Kp bacteria strains. Biofilm formation was investigated after GENT-EDTA/Nio administration through different detection methods, which showed that this formulation reduces biofilm formation. The effect of GENT-EDTA/Nio on the expression of biofilm-related genes (mrkA, ompA, and vzm) was estimated using QRT-PCR. MTT assay was used to evaluate the toxicity effect of niosomal formulations on HFF cells. The present study results indicate that GENT-EDTA/Nio decreases Kp's resistance to antibiotics and increases its antibiotic and anti-biofilm activity and could be helpful as a new approach for drug delivery.

Emerging nanoparticle designs against bacterial infections

The rise of antibiotic resistance has caused the prevention and treatment of bacterial infections to be less effective. Therefore, researchers turn to nanomedicine for novel and effective antibacterial therapeutics. The effort resulted in the first-generation antibacterial nanoparticles featuring the ability to improve drug tolerability, circulation half-life, and efficacy. Toward developing the next-generation antibacterial nanoparticles, researchers have integrated design elements that emphasize physical, broad-spectrum, biomimetic, and antivirulence mechanisms. This review highlights four emerging antibacterial nanoparticle designs: inorganic antibacterial nanoparticles, responsive antibacterial nanocarriers, virulence nanoscavengers, and antivirulence nanovaccines. Examples in each design category are selected and reviewed, and their structure-function relationships are discussed. These emerging designs open the door to nontraditional antibacterial nanomedicines that rely on mechano-bactericidal, function-driven, nature-inspired, or virulence-targeting mechanisms to overcome antibiotic resistance for more effective antibacterial therapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Anticorrosion Coating with Heterogeneous Assembly of Nanofillers Modulated by a Magnetic Field

An anticorrosive coating with randomly distributed passive barriers and regionally enriched active corrosion inhibitors is developed by integrating mica nanosheets (MNSs) and magnetic-responsive core-shell mesoporous nanoparticles with 2-mercaptobenzothiazole (Fe₃O₄@mSiO₂/MBT) under magnetic field incubation. The bottom enriched Fe₃O₄@mSiO₂/MBT rapidly releases the MBT to form a passivation layer on corrosion sites, enhancing the corrosion inhibition efficiency by 30.36% compared with the control (NP_0.7EP-R). The impedance modulus |Z|_0.01 Hz of the sample (NP_0.7/MNS_0.5/EP) increases by five orders of magnitude compared with that of its control (NP_0.7/MNS₀EP) after 30 days of corrosion immersion. NP_0.7/MNS_0.5/EP exhibited the lowest corrosion rate (3.984 × 10^-5 mm/year) as compared to the other samples. Notably, the coating in a fractured state still maintains superior corrosion inhibition even after 40 day salt spray testing. The differentiated distribution of nanofillers was well confirmed by optical microscopy and SEM-EDS, and the synergistic effect of the active/passive integrated anticorrosive coating with merits of both comprehensive protection and fast responsiveness was systematically explored.

Exploring Possible Ways to Enhance the Potential and Use of Natural Products through Nanotechnology in the Battle against Biofilms of Foodborne Bacterial Pathogens

Biofilms enable pathogenic bacteria to survive in unfavorable environments. As biofilm-forming pathogens can cause rapid food spoilage and recurrent infections in humans, especially their presence in the food industry is problematic. Using chemical disinfectants in the food industry to prevent biofilm formation raises serious health concerns. Further, the ability of biofilm-forming bacterial pathogens to tolerate disinfection procedures questions the traditional treatment methods. Thus, there is a dire need for alternative treatment options targeting bacterial pathogens, especially biofilms. As clean-label products without carcinogenic and hazardous potential, natural compounds with growth and biofilm-inhibiting and biofilm-eradicating potentials have gained popularity as natural preservatives in the food industry. However, the use of these natural preservatives in the food industry is restricted by their poor availability, stability during food processing and storage. Also there is a lack of standardization, and unattractive organoleptic qualities. Nanotechnology is one way to get around these limitations and as well as the use of underutilized bioactives. The use of nanotechnology has several advantages including traversing the biofilm matrix, targeted drug delivery, controlled release, and enhanced bioavailability, bioactivity, and stability. The nanoparticles used in fabricating or encapsulating natural products are considered as an appealing antibiofilm strategy since the nanoparticles enhance the activity of the natural products against biofilms of foodborne bacterial pathogens. Hence, this literature review is intended to provide a comprehensive analysis of the current methods in nanotechnology used for natural products delivery (biofabrication, encapsulation, and nanoemulsion) and also discuss the different promising strategies employed in the recent and past to enhance the inhibition and eradication of foodborne bacterial biofilms.

Regulable Polyelectrolyte-Surfactant Complex for Antibacterial Biomedical Catheter Coating via a Readily Scalable Route

Constructing multifunctional surfaces is one of the practical approaches to address catheter-related multiple complications but is generally time-consuming and substrate-dependent. Herein, a novel anti-adhesion, antibacterial, low friction, and robustness coating on medical catheters are developed via a universal and readily scalable method based on a regulable polyelectrolyte surfactant complex. The complex is rapidly assembled in one step by electrostatic and hydrophobic interactions between organosilicon quaternary ammonium surfactant (N⁺ _Si ) and adjustable polyelectrolyte with cross-linkable, anti-adhesive, and anionic groups. The alcohol-soluble feature of the complex is conducive to the rapid formation of coatings on any medical device with arbitrary shapes via dip coating. Different from the conventional polyelectrolyte-surfactant complex coating, the regulated complex coating with nonleaching mode could be stable in harsh conditions (high concentration salt solution, organic reagents, etc.) because of the cross-linked structure while improving the biocompatibility and reducing the adhesion of various bacteria, proteins, and blood cells. The coated catheter exhibits good antibacterial infection in vitro and in vivo, owing to the synergistic effect of N⁺ _Si and zwitterionic groups. Therefore, the rationally designed complex supplies a facile coating approach for the potential development in combating multiple complications of the medical catheter.

Bio-Inspired Self-Adaptive Nanocomposite Array: From Non-antibiotic Antibacterial Actions to Cell Proliferation

Pathogenic bacterial infection and poor native tissue integration are two major issues encountered by biomaterial implants and devices, which are extremely hard to overcome within a single surface, especially for those without involvement of antibiotics. Herein, a self-adaptive surface that can transform from non-antibiotic antibacterial actions to promotion of cell proliferation is developed by in situ assembly of bacteriostatic 3,3'-diaminodipropylamine (DADP)-doped zeolitic imidazolate framework-8 (ZIF-8) on bio-inspired nanopillars. Initially, the nanocomposite surface shows impressive antibacterial effects, even under severe bacterial infection, due to the combination of mechano-bactericidal activity from a nanopillar structure and bacteriostatic activity contributed by pH-responsive release of DADP. After the complete degradation of the ZIF-8 layer, the refurbished nanopillars not only can still physically rupture bacterial membrane but also facilitate mammalian cell proliferation, due to the obvious difference in cell size. More strikingly, the nanocomposite surface totally avoids the usage of antibiotics, eradicating the potential risk of antimicrobial resistance, and the surface exhibited excellent histocompatibility and lower inflammatory response properties as revealed by in vivo tests. This type of self-adaptive surface may provide a promising alternative for addressing the intractable implant-associated requirements, where antibiotic-free antibacterial activity and native tissue integration are both highly needed.

Charge-switchable MOF nanocomplex for enhanced biofilm penetration and eradication

Bacterial biofilm is notorious for causing chronic infections, whose antibiotic treatment is bringing about severe multidrug resistance and environmental contamination. Stimuli-responsive nanocarriers have become encouraging materials to combat biofilm infections with high efficiency and low side effect. Herein, a charge-switchable and pH-responsive nanocomplex is fabricated via a facile aqueous one-pot zeolitic imidazolate framework-8 (ZIF-8) encapsulation of proteinase K (PK) and photosensitizer Rose Bengal (RB), for enzymatic and photodynamic therapies (PDT) against biofilm infections. Once encountering in acidic microenvironment, the surface charge of nanocomplex can switch self-adaptively from negative to positive, hence remarkably facilitating the biofilm penetration of nanocomplex. After acid-induced decomposition of nanocomplex, the released PK degrades biofilm matrix and loosens its structure, promoting diffusion of RB inside the biofilm. Afterwards, upon visible light illumination, the RB generates highly reactive oxygen species (ROS), which can readily and efficiently kill the remained bacteria even in the biofilm core. The charge-assisted penetration makes PK and RB fully functional, resulting in a cooperative effect concerning high biofilm eradication capacity, as testified by biofilm models both in vitro and in vivo. The green synthesis and good therapeutic performance of the nanocomplex manifests its considerable potential as a nontoxic and effective platform for biofilm treatment.

Biofilms: Formation, Research Models, Potential Targets, and Methods for Prevention and Treatment

Due to the continuous rise in biofilm-related infections, biofilms seriously threaten human health. The formation of biofilms makes conventional antibiotics ineffective and dampens immune clearance. Therefore, it is important to understand the mechanisms of biofilm formation and develop novel strategies to treat biofilms more effectively. This review article begins with an introduction to biofilm formation in various clinical scenarios and their corresponding therapy. Established biofilm models used in research are then summarized. The potential targets which may assist in the development of new strategies for combating biofilms are further discussed. The novel technologies developed recently for the prevention and treatment of biofilms including antimicrobial surface coatings, physical removal of biofilms, development of new antimicrobial molecules, and delivery of antimicrobial agents are subsequently presented. Finally, directions for future studies are pointed out.

Nitric oxide-propelled nanomotors for bacterial biofilm elimination and endotoxin removal to treat infected burn wounds

Biofilm infection is regarded as a major contributing factor to the failure of burn treatment and a persistent inflammatory state delays healing and leads to the formation of chronic wounds. Herein, self-propelled nanomotors (NMs) are proposed to enhance biofilm infiltration, bacterial destruction, and endotoxin clearance to accelerate the healing of infected burn wounds. Janus nanoparticles (NPs) were prepared through partially coating Fe₃O₄ NPs with polydopamine (PDA) layers, and then polymyxin B (PMB) and thiolated nitric oxide (SNO) donors were separately grafted onto the Janus NPs to obtain IO@PMB-SNO NMs. In response to elevated glutathione (GSH) levels in biofilms, NO generation from one side of the Janus NPs leads to self-propelled motion and deep infiltration into biofilms. The local release of NO could destroy bacteria inside the biofilm, which provides a non-antibiotic antibiofilm approach without the development of drug resistance. In addition to intrinsic antibacterial effects, the PMB grafts preferentially bind with bacteria and the active motion enhances lipopolysaccharide (LPS) clearance and then significantly attenuates the production of inflammatory cytokines and reactive oxide species by macrophages. Partial-thickness burn wounds were established on mice and infected with P. aeruginosa, and NM treatment almost fully destroyed the bacteria in the wounds. IO@PMB-SNO NMs absorb LPS and remove it from the wounds under a magnetic field, which downregulates the interleukin-6 and tumor necrosis factor-α levels in tissues. The infected wounds were completely healed with the deposition and arrangement of collagen fibers and the generation of skin features similar to those of normal skin. Thus, IO@PMB-SNO NMs achieved multiple-mode effects, including GSH-triggered NO release and self-propelled motion, the NO-induced non-antibiotic elimination of biofilms and bacteria, and PMB-induced endotoxin removal. This study offers a feasible strategy, with integrated antibiofilm and anti-inflammatory effects, for accelerating the healing of infected burn wounds.

Nanocarriers for combating biofilms: advantages and challenges

Bacterial biofilms are highly resistant to antibiotics and pose a great threat to human and animal health. The control and removal of bacterial biofilms have become an important topic in the field of bacterial infectious diseases. Nanocarriers show great anti-biofilm potential because of their small particle size and strong permeability. In this review, the advantages of nanocarriers for combating biofilms are analyzed. Nanocarriers can act on all stages of bacterial biofilm formation and diffusion. They can improve the scavenging effect of biofilm by targeting biofilm, destroying extracellular polymeric substances, and enhancing the biofilm permeability of antimicrobial substances. Nanocarriers can also improve the antibacterial ability of antimicrobial drugs against bacteria in biofilm by protecting the loaded drugs and controlling the release of antimicrobial substances. Additionally, we emphasize the challenges faced in using nanocarrier formulations and translating them from a preclinical level to the clinical setting.

Advances and Perspective on Antimicrobial Nanomaterials for Biomedical Applications

Microbial infection and antibiotic resistance is recognized as a serious problem to society from both an economical perspective and a health concern. To tackle this problem, “nanotechnology,” a multidisciplinary field of research, has provided a plethora of nanomaterials for potential applications in the antimicrobial sector. This letter discusses how antimicrobial nanomaterials are shaping this challenging field and being evaluated as therapeutic and medication delivery agents. The recently designed smart antimicrobial surfaces with switchable features that displayed synergistic antibacterial action were also highlighted. To end, we provide the current scenario and future perspectives with regards to emerging antimicrobial nano-engineered materials and nanotechnology.