Progress of tumor-resident intracellular bacteria for cancer therapy

Emerging studies have disclosed the pivotal role of cancer-associated microbiota in supporting cancer development, progression and dissemination, with the in-depth comprehending of tumor microenvironment. In particular, certain invasive bacteria that hide in various cells within the tumor tissues can render assistance to tumor growth and invasion through intricate mechanisms implicated in multiple branches of cancer biology. Thus, tumor-resident intracellular microbes are anticipated as next-generation targets for oncotherapy. This review is intended to delve into these internalized bacteria-driven cancer-promoting mechanisms and explore diversified antimicrobial therapeutic strategies to counteract the detrimental impact caused by these intruders, thereby improving therapeutic benefit of antineoplastic therapy.

Fluoroamphiphilic polymers exterminate multidrug-resistant Gram-negative ESKAPE pathogens while attenuating drug resistance

ESKAPE pathogens are a panel of most recalcitrant bacteria that could "escape" the treatment of antibiotics and exhibit high incidence of drug resistance. The emergence of multidrug-resistant (MDR) ESKAPE pathogens (particularly Gram-negative bacteria) accounts for high risk of mortality and increased resource utilization in health care. Worse still, there has been no new class of antibiotics approved for exterminating the Gram-negative bacteria for more than 50 years. Therefore, it is urgent to develop novel antibacterial agents with low resistance and potent killing efficacy against Gram-negative ESKAPE pathogens. Herein, we present a class of fluoropolymers by mimicking the amphiphilicity of cationic antimicrobial peptides. Our optimal fluoroamphiphilic polymer (PD45HF5) displayed selective antimicrobial ability for all MDR Gram-negative ESAKPE pathogens, low resistance, high in vitro cell selectivity, and in vivo curative efficacy. These findings implied great potential of fluoroamphiphilic cationic polymers as promising antibacterial agents against MDR Gram-negative ESKAPE bacteria and alleviating antibiotic resistance.

A New Theranostic Platform Against Gram-Positive Bacteria Based on Near-Infrared-Emissive Aggregation-Induced Emission Nanoparticles

Infections induced by Gram-positive bacteria pose a great threat to public health. Antibiotic therapy, as the first chosen strategy against Gram-positive bacteria, is inevitably associated with antibiotic resistance selection. Novel therapeutic strategies for the discrimination and inactivation of Gram-positive bacteria are thus needed. Here, a specific type of aggregation-induced emission luminogen (AIEgen) with near-infrared fluorescence emission as a novel antibiotic-free therapeutic strategy against Gram-positive bacteria is proposed. With the combination of a positively charged group into a highly twisted architecture, self-assembled AIEgens (AIE nanoparticles (NPs)) at a relatively low concentration (5 µm) exhibited specific binding and photothermal effect against living Gram-positive bacteria both in vitro and in vivo. Moreover, toxicity assays demonstrated excellent biocompatibility of AIE NPs at this concentration. All these properties make the AIE NPs as a novel generation of theranostic platform for combating Gram-positive bacteria and highlight their promising potential for in vivo tracing of such bacteria.

Fighting bacteria with bacteria: A biocompatible living hydrogel patch for combating bacterial infections and promoting wound healing

Bacterial infections are among the most critical global health challenges that seriously threaten the security of human. To address this issue, a biocompatible engineered living hydrogel patch was developed by co-embedding engineered photothermal bacteria (EM), photosensitizer (porphyrin) and reactive oxygen species amplifier (laccase) in a protein hydrogel. Remarkably, the genetice engineered bacteria can express melanin granules in vivo and this allows them to exhibit photothermal response upon being exposed to NIR-II laser (1064 nm) irradiation. Besides, electrostatically adhered tetramethylpyridinium porphyrin (TMPyP) on the bacterial surface and encapsulated laccase (Lac) in protein gel can generate highly toxic singlet oxygen (1O2) and hydroxyl radical (·OH) in the presence of visible light and lignin, respectively. Interestingly, the engineered bacteria hydrogel patch (EMTL@Gel) was successfully applied in synergistic photothermal, photodynamic and chemodynamic therapy, in which it was able to efficiently treat bacterial infection in mouse wounds and enhance wound healing. This work demonstrates the concept of "fighting bacteria with bacteria" combining bacterial engineering and material engineering into an engineered living hydrogel path that can synergistically boost the therapeutic outcome. STATEMENT OF SIGNIFICANCE: Genetically engineered bacteria produce melanin granules in vivo, exhibiting remarkable photothermal properties. These bacteria, along with a photosensitizer (TMPyP) and a reactive oxygen species amplifier (laccase), are incorporated into a biocompatible protein hydrogel patch. Under visible light, the patch generates toxic singlet oxygen (1O2) and hydroxyl radical (·OH), demonstrates outstanding synergistic effects in photothermal, photodynamic, and chemodynamic therapy, effectively treating bacterial infections and promoting wound healing in mice.

Essential considerations towards development of effective nasal antibiotic formulation: features, strategies, and future directions

INTRODUCTION

Intranasal antibiotic products are gaining popularity as a promising method of administering antibiotics, which provide numerous benefits, e.g. enhancing drug bioavailability, reducing adverse effects, and potentially minimizing resistance threats. However, some issues related to the antibiotic substances and nasal route challenges must be addressed to prepare effective formulations.

AREAS COVERED

This review focuses on the valuable points of nasal delivery as an alternative route for administering antibiotics, coupled with the challenges in the nasal cavity that might affect the formulations. Moreover, this review also highlights the application of nasal delivery to introduce antibiotics for local therapy, brain targeting, and systemic effects that have been conducted. In addition, this viewpoint provides strategies to maintain antibiotic stability and several crucial aspects to be considered for enabling effective nasal formulation.

EXPERT OPINION

In-depth knowledge and understanding regarding various key considerations with respect to the antibiotic substances and nasal route delivery requirement in preparing effective nasal antibiotic formulation would greatly improve the development of nasally administered antibiotic products, enabling better therapeutic outcomes of antibiotic treatment and establishing appropriate use of antibiotics, which in turn might reduce the chance of antibiotic resistance and enhance patient comfort.

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.

Strategies for the eradication of intracellular bacterial pathogens

Intracellular pathogens affect a significant portion of world population and cause millions of deaths each year. They can invade host cells and survive inside them and are extremely resistant to immune systems and antibiotics. Current treatments have limitations, and therefore, new effective therapies are needed to combat this ongoing health challenge. Active research efforts have been made to develop many new strategies to eradicate these intracellular pathogens. In this review, we focus on the intracellular bacterial pathogens and first introduce several representative intracellular bacteria and the diseases they cause. We then discuss the challenges in eradicating these bacteria and summarize the current therapeutics for intracellular bacteria. Finally, recent advances in intracellular bacteria eradication are highlighted.

Bactericidal and Antioxidant Potential of Moringa oleifera Capped Silver Nanoparticles under Varied Conditions

Microbial infections have consistently been identified as one of the major threats to global health. In this regard, the current study was designed to synthesize and evaluate the antibacterial activity of Mo‐AgNPs at various concentrations (2, 4, and 8 mg/mL), temperatures (4 °C, 25 °C, 37 °C, and 85 °C) and pH (4, 7, and 11) against Gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Aeromonas veronii) and Gram‐positive bacteria (Staphylococcus aureus, Bacillus subtilis) by the well diffusion method as well as antioxidant potential using DPPH assay at 2 mg/mL and 4 mg/mL. Fabrication of Mo‐AgNPs was authenticated by UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X‐ray diffraction (XRD). Mo‐AgNPs produced a significant zone of growth inhibition (21.0±0.3 mm) against B. subtilis at 8 mg/mL. At 25 °C, a significant zone of growth inhibition (21.0±0.8 mm) was measured against E. coli. Similarly, at pH 4, Mo‐AgNPs showed significantly highest growth inhibition zones of 12.0±7.5 mm, 12.0±6.3 mm, and 12.0±9.8 mm against P. aeruginosa, K. pneumoniae, and A. veronii, respectively. The present study results indicated that Mo‐AgNPs are stable under varied conditions. Significant free radical scavenging activity (82±0.5 %) of Mo‐AgNPs at 4 mg/mL was observed, which revealed the antioxidant potential of the Mo‐AgNPs.

Dye-sensitized rare-earth-doped nanoprobe for simultaneously enhanced NIR-II imaging and precise treatment of bacterial infection

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for causing life-threatening infections that result in high morbidity and mortality rates. The development of advanced imaging and therapeutic methods for in vivo diagnosis and treatment of MRSA infections remains challenging. Here, we develop a hybrid nanoplatform based on rare-earth-doped nanoparticles (RENPs) sensitized by a moiety-engineered near-infrared (NIR) TPEO-820 dye and with a ZIF-8 layer that incorporates CysNO, a photochemically triggered nitric oxide donor. We then use the hybrid for both NIR-II bioimaging and photoactivatable treatment of MRSA-infected wounds. We show that the NIR dye sensitization leads to an 8.5-fold enhancement of the downshifting emission and facilitates deep-tissue NIR-II imaging of bacterial infections. Moreover, the sensitization strategy enhances the UV emission of RENPs by two orders of magnitude, leading to the efficiently controllable release of nitric oxide for effective disinfection of MRSA in vitro and in vivo. The hybrid nanoplatform thus offers promising opportunities for simultaneous localization and controllable treatment of MRSA. STATEMENT OF SIGNIFICANCE: Early detection and treatment of MRSA infections are crucial for reducing public health risks. It is a significant challenge that develops sensitive in vivo diagnosis and complete elimination of drug-resistant bacterial infections. Herein, a nanoplatform has been developed for photoactivatable therapy of MRSA infections and deep tissue NIR-II imaging. This platform utilizes lanthanide-doped rare earth nanoparticles (RENPs) that are sensitized by a moiety-engineered near-infrared (NIR) dye TPEO-820. The TPEO-820 sensitized RENPs exhibit 5 times increase in the release of NO concentration for MRSA treatment compared to unsensitized RENPs, enabling precise therapy of MRSA infection both in vitro and in vivo. Moreover, the platform demonstrates NIR-II luminescence in vivo, allowing for sensitive imaging in deep tissue for MRSA infection.

Quality by design-based optimization of in situ ionic-sensitive gels of amoxicillin-loaded bovine serum albumin nanoparticles for enhanced local nasal delivery

A recommended first-line acute bacterial rhinosinusitis (ABR) treatment regimen includes a high dose of orally administered amoxicillin, despite its frequent systemic adverse reactions coupled with poor oral bioavailability. Therefore, to overcome these issues, nasal administration of amoxicillin might become a potential approach for treating ABR locally. The present study aimed to develop a suitable carrier system for improved local nasal delivery of amoxicillin employing the combination of albumin nanoparticles and gellan gum, an ionic-sensitive polymer, under the Quality by Design methodology framework. The application of albumin nanocarrier for local nasal antibiotic therapy means a novel approach by hindering the nasal absorption of the drug through embedding into an in situ gelling matrix, further prolonging the drug release in the nasal cavity. The developed formulations were characterized, including mucoadhesive properties, in vitro drug release and antibacterial activities. Based on the results, 0.3 % w/v gellan gum concentration was selected as the optimal in situ gelling matrix. Essentially, each formulation adequately inhibited the growth of five common nasal pathogens in ABR. In conclusion, the preparation of albumin-based nanoparticles integrated with in situ ionic-sensitive polymer provides promising ability as nanocarrier systems for delivering amoxicillin intranasally for local antibiotic therapy.

Bacterial memory in antibiotic resistance evolution and nanotechnology in evolutionary biology

Bacterial memory refers to the phenomenon in which past experiences influence current behaviors in response to changing environments. It serves as a crucial process that enables adaptation and evolution. We first summarize the state-of-art approaches regarding history-dependent behaviors that impact growth dynamics and underlying mechanisms. Then, the phenotypic and genotypic origins of memory and how encoded memory modulates drug tolerance/resistance are reviewed. We also provide a summary of possible memory effects induced by antimicrobial nanoparticles. The regulatory networks and genetic underpinnings responsible for memory building partially overlap with nanoparticle and drug exposures, which may raise concerns about the impact of nanotechnology on adaptation. Finally, we provide a perspective on the use of nanotechnology to harness bacterial memory based on its unique mode of actions on information processing and transmission in bacteria. Exploring bacterial memory mechanisms provides valuable insights into acclimation, evolution, and the potential applications of nanotechnology in harnessing memory.

Engineered live bacteria suppress Pseudomonas aeruginosa infection in mouse lung and dissolve endotracheal-tube biofilms

Engineered live bacteria could provide a new modality for treating lung infections, a major cause of mortality worldwide. In the present study, we engineered a genome-reduced human lung bacterium, Mycoplasma pneumoniae, to treat ventilator-associated pneumonia, a disease with high hospital mortality when associated with Pseudomonas aeruginosa biofilms. After validating the biosafety of an attenuated M. pneumoniae chassis in mice, we introduced four transgenes into the chromosome by transposition to implement bactericidal and biofilm degradation activities. We show that this engineered strain has high efficacy against an acute P. aeruginosa lung infection in a mouse model. In addition, we demonstrated that the engineered strain could dissolve biofilms formed in endotracheal tubes of patients with ventilator-associated pneumonia and be combined with antibiotics targeting the peptidoglycan layer to increase efficacy against Gram-positive and Gram-negative bacteria. We expect our M. pneumoniae-engineered strain to be able to treat biofilm-associated infections in the respiratory tract.

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.

Infection control measures against multidrug-resistant Gram-negative bacteria in children and neonates

The increase in infections caused by multidrug-resistant (MDR) Gram-negative bacteria in neonatal and pediatric intensive care units over recent years is alarming. MDR Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii have constituted the main causes of the MDR Gram-negative bacteria problem. The implementation of infection control measures such as hand hygiene, cohorting of patients, contact precautions, active surveillance and environmental cleaning could diminish their spread. Recently, water safety has been identified as a major component of infection control policies. The aim of the current review is to highlight the effectiveness of these infection control measures in managing outbreaks caused by MDR Gram-negative bacteria in neonatal and pediatric intensive care units and highlight future perspectives on the topic.

Epsilon-poly-l-lysine conjugated erythromycin for enhanced antibiotic therapy

Antibiotic resistance is a big threat to public health. How to improve the therapeutic efficacy of conventional antibiotics is an effective way to address this issue. In order to enhance the antibacterial activity of conventional antibiotic erythromycin (EM), EM is conjugated to positively charged ε-poly-l-lysine (EPL) to obtain EPL modified EM (EPL-EM). The grafting ratio of EM can be calculated from the ¹H NMR spectrum. EPL-EM is stable in physiological environment, while EM can be readily released from EPL-EM upon incubating with esterase which can be secreted by most bacteria. Because of the presence of cationic EPL, EPL-EM showed much stronger antibacterial activity than free EM, with much lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Moreover, compared to free EM, the development of drug resistance can be slowed down if EPL-EM is used, which can be ascribed to the reduction of EM dosage. Meanwhile, EPL-EM cannot induce hemolysis and cytotoxicity, which indicates that EPL-EM exhibits excellent biocompatibility. The design of EPL-EM with enhanced antibacterial activity and excellent biocompatibility provides an innovative way to combat antibiotic resistance.

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.

Evaluation of scolicidal potential of salicylate coated zinc nanoparticles against Echinococcus granulosus protoscoleces

Echinococcosis is a zoonotic disease caused by larval stages of the Echinococcus genus (metastasis). In this study, salicylate-coated Zinc oxide nanoparticles (SA-ZnO-NPs) were fabricated and characterized by SEM, FTIR and XRD analytical techniques. After that, different doses of SA-ZnO-NPs, SA and ZnO-NPs were taken to assess scolicidal potency. Scanning electron microscopy (SEM) micrographs were also used to evaluate the morphological deformities of treated protoscoleces. Furthermore, Caspase-3&7 inductions were examined in protoscoleces cysts treated with all formulations. Based on SEM and DLS analyses, the size of SA-ZnO-NPs was between 30 and 40 nm, with a spherical shape. The FTIR spectrum verified the presence of SA functional groups on the ZnO coating. At 20 min, SA-ZnO-NPs at 2000 μg/ml exhibited the greatest activity on protoscolices with 100% mortality, followed by ZnO-NPs at 1500 μg/ml at 10 min and SA alone at 2000 μg/ml at 30 min. The activation of Caspase-3&7 apoptotic enzyme was determined for 2000 μg/ml of SA-ZnO-NPs, ZnO-NPs and SA to be 16.4, 31.4, and 35.7%, respectively. The SEM image revealed apoptogenic alterations and the induction of tegument surface wrinkles, as well as abnormalities in rostellum protoscolices. According to the current study, SA-ZnO-NPs have a high mortality rate against hydatid cyst protoscolices. As a result, further studies on the qualitative assessment of these nanoformulations in vivo and preclinical animal trials seem to be required. Furthermore, the adoption of nano-drugs potentially offers alternative therapeutic approaches to combat hydatid cysts.

Silver nanoparticles modified hFGF2-linking camelina oil bodies accelerate infected wound healing

Bacterial infection wounds are common in life. At present, although various wound materials have shown antibacterial activity, there is a lack of overall strategy to promote wound healing. Therefore, it is necessary to develop multifunctional wound materials. In this study, silver nanoparticles (Ag NPs) modified camelina oil bodies (OB) which surface covalently bonded human fibroblast growth factor 2 (Ag NPs-hFGF2-OB) were designed for the treatment of bacterial infection wounds. The prepared Ag NPs-hFGF2-OB not only act as an antibacterial agent to realize sterilization, but also act as a tissue repair agent that effectively promotes wound healing. Ag⁺ was reduced in situ to Ag NPs by ascorbic acid, and the activity of hFGF2 protein was not affected after hFGF2-OB was modified by Ag NPs, which displaying broad apectrum antibacterial ability for both S. aureus and E. coli, with an antibacterial rate of more than 70 % (the concentration of Ag NPs was 20 μg/mL, the hFGF2 protein concentration was 20 µg/mL). Ag NPs-hFGF2-OB can effectively promote the migration of NIH/3T3 cells, showing good biocompatibility. The mouse bacterial infection wound model experiments proved that the wound healing rate of Ag NPs-hFGF2-OB group (the concentration of Ag NPs was 20 μg/mL, the hFGF2 protein concentration was 20 µg/mL) was much higher than other treatment groups, especially on the 7th day after treatment, the wound healing rate reached 71.71 ± 2.38 %, while the healing rate of other treatment groups were only 34.54 ± 1.10 %, 37.08 ± 2.85 % and 47.99 ± 2.01 %. Therefore, Ag NPs-hFGF2-OB, which can inhibit bacterial growth, promotes collagen deposition, granulation tissue regeneration and angiogenesis without any significant toxicity, shows good potential for application in the repair of bacterial infection wounds.

Recent advances in responsive antibacterial materials: design and application scenarios

Bacterial infection is one of the leading causes of death globally, although modern medicine has made considerable strides in the past century. As traditional antibiotics are suffering from the emergence of drug resistance, new antibacterial strategies are of great interest. Responsive materials are appealing alternatives that have shown great potential in combating resistant bacteria and avoiding the side effects of traditional antibiotics. In this review, the responsive antibacterial materials are introduced in terms of stimulus signals including intrinsic (pH, enzyme, ROS, etc.) and extrinsic (light, temperature, magnetic fields, etc.) stimuli. Their biomedical applications in therapeutics and medical devices are then discussed. Finally, the author's perspective of the challenge and the future of such a system is provided.

Stimuli-Activable Metal-Bearing Nanomaterials and Precise On-Demand Antibacterial Strategies

Bacterial infections remain the leading cause of death worldwide today. The emergence of antibiotic resistance has urged the development of alternative antibacterial technologies to complement or replace traditional antibiotic treatments. In this regard, metal nanomaterials have attracted great attention for their controllable antibacterial functions that are less prone to resistance. This review discusses a particular family of stimuli-activable metal-bearing nanomaterials (denoted as SAMNs) and the associated on-demand antibacterial strategies. The various SAMN-enabled antibacterial strategies stem from basic light and magnet activation, with the addition of bacterial microenvironment responsiveness and/or bacteria-targeting selectivity and therefore offer higher spatiotemporal controllability. The discussion focuses on nanomaterial design principles, antibacterial mechanisms, and antibacterial performance, as well as emerging applications that desire on-demand and selective activation (i.e., medical antibacterial treatments, surface anti-biofilm, water disinfection, and wearable antibacterial materials). The review concludes with the authors' perspectives on the challenges and future directions for developing industrial translatable next-generation antibacterial strategies.

Development of Thermoresponsive-Gel-Matrix-Embedded Amoxicillin Trihydrate-Loaded Bovine Serum Albumin Nanoparticles for Local Intranasal Therapy

A high dose of amoxicillin is recommended as the first-line therapy for acute bacterial rhinosinusitis (ABR). However, oral administration of amoxicillin is connected to many adverse reactions coupled with moderate bioavailability (~60%). Therefore, this study aimed to develop a topical nasal preparation of amoxicillin, employing a thermoresponsive nanogel system to increase nasal residence time and prolong drug release. Rheological investigations revealed that formulations containing 21−23% w/w Poloxamer 407 (P407) were in accordance with the requirement of nasal administration (gelling temperature ~35 °C). The average hydrodynamic diameter (<200 nm), pH (6.7−6.9), and hypertonic osmolality (611−663 mOsmol/L) of the in situ gelling nasal nanogel appeared as suitable characteristics for local rhinosinusitis treatment. Moreover, taking into account the mucoadhesive strength and drug release studies, the 21% w/w P407 could be considered as an optimized concentration for effective nasal delivery. Antibacterial activity studies showed that the ability of amoxicillin-loaded in situ gelling nasal nanogel to inhibit bacterial growth (five common ABR pathogens) preserved its effectiveness in comparison to 1 mg/mL amoxicillin aqueous solution as a positive control. Altogether, the developed amoxicillin-loaded in situ gelling thermoresponsive nasal nanogel can be a potential candidate for local antibiotic therapy in the nasal cavity.

Mechanisms of Metallic Nanomaterials to Induce an Antibacterial Effect

Pathogenic microorganisms, including bacteria, are becoming resistant to most existing drugs, which increases the failure of pharmacologic treatment. Therefore, new nanomaterials were studied to spearhead improvement against the same resistant pathogenic bacteria. This has increased the mortality in the world population, principally in under-developed countries. Moreover, recently there has been research to find new drug formulations to kill the most dangerous microorganisms, such as bacteria cells which should avoid the spread of disease. Therefore, lately, investigations have been focusing on nanomaterials because they can exhibit the capacity to show an antibacterial effect. These studies have been trying oriented in their ability to produce an improvement to get antibacterial damage against the same pathogenic bacteria resistance. However, there are many problems with the use of nanoparticles. One of them is understanding how they act against bacteria, "their mechanism(s) action" to induce reduction or even kill the bacterial strains. Therefore, it is essential to understand the specific mechanism(s) of each nanomaterial used to observe the interaction between bacteria cells and nanoparticles. In addition, since nanoparticles can be functionalized with different antibacterial drugs, it is necessary to consider and distinguish the antibacterial activity of the nanoparticles from the antibacterial activity of the drugs to avoid confusion about how the nanoparticles work. Knowledge of these differences can help better understand the applications of the primary nanoparticles (i.e., Ag, Au, CuO, ZnO, and TiO², among others) described in detail in this review which are toxic against various bacterial strains.

Current approaches of nanomedicines in the market and various stage of clinical translation

Compared with traditional drug therapy, nanomedicines exhibit intriguing biological features to increase therapeutic efficiency, reduce toxicity and achieve targeting delivery. This review provides a snapshot of nanomedicines that have been currently launched or in the clinical trials, which manifests a diversified trend in carrier types, applied indications and mechanisms of action. From the perspective of indications, this article presents an overview of the applications of nanomedicines involving the prevention, diagnosis and treatment of various diseases, which include cancer, infections, blood disorders, cardiovascular diseases, immuno-associated diseases and nervous system diseases, etc. Moreover, the review provides some considerations and perspectives in the research and development of nanomedicines to facilitate their translations in clinic.

Preparation and in vivo bacteriostatic application of PPDO-coated Ag loading TiO2 nanoparticles

Implant-associated infections limit the clinical application of implants therapy; hence, exploiting strategies to prevent biomaterial-associated infections has become important. Therefore, in this study, a series of poly (p-dioxanone) (PPDO)-coated Ag loading TiO₂ nanoparticles (Ag@TiO₂-PPDO) was synthesized to be applied as bacteriostatic coating materials that could be easily dispersed in organic solvent and coated onto implantable devices via temperate methods such as electrospraying. The lattice parameters of TiO₂ were a = 0.504 nm, b = c = 1.05 nm, alpha = beta = gamma = 90 degree and the size of crystallite was about 13 nm, indicating that part of Ag has been embedded into crystal defects of TiO₂. Both XRD and TEM determinations indicated the successful grating of PPDO on the surface of Ag@TiO₂. Among Ag@TiO₂ nanoparticles with various Ag loading quantities, 12% Ag@TiO₂ nanoparticles exhibited relatively higher grafting efficiency and Ag contents on the surface of grafted composites. In addition, 12% Ag@TiO₂-PPDO exhibited the best bacteriostatic effect in vitro owing to its higher grafted efficiency and relatively short length of PPDO segments. Subsequently, Ag@TiO₂-PPDO was coated on the surface of a poly lactic-co-glycolic acid (PLGA) electrospun membrane via the electrospraying method. Finally, the in vivo bacteriostatic effect of 12% Ag@TiO₂-PPDO coating was verified by implanting 12% Ag@TiO₂-PPDO-coated PLGA membrane into a rat subcutaneously combined with an injection of Staphylococcus aureus at implanting sites.

Co-Delivery of Nano-Silver and Vancomycin via Silica Nanopollens for Enhanced Antibacterial Functions

Infectious diseases caused by bacteria have led to a great threat to public health. With the significant advances in nanotechnology in recent decades, nanomaterials have emerged as a powerful tool to boost antibacterial performance due to either intrinsic bactericidal properties or by enhancing the delivery efficiency of antibiotics for effective pathogen killing. Vancomycin, as one of the most widely employed antimicrobial peptides, has a potent bactericidal activity, but at the same time shows a limited bioavailability. Silver nanoparticles have also been extensively explored and were found to have a well-recognized antibacterial activity and limited resistance potential; however, how to prevent nanosized Ag particles from aggregation in biological conditions is challenging. In this study, we aimed to combine the advantages of both vancomycin and nano-Ag for enhanced bacterial killing, where both antibacterial agents were successfully loaded onto a silica nanoparticle with a pollen-like morphology. The morphology of nano-Ag-decorated silica nanopollens was characterized using transmission electron microscopy and elemental mapping through energy dispersive spectroscopy. Silver nanoparticles with a size of 10–25 nm were observed as well-distributed on the surface of silica nanoparticles of around 200 nm. The unique design of a spiky morphology of silica nano-carriers promoted the adhesion of nanoparticles towards bacterial surfaces to promote localized drug release for bacterial killing, where the bacterial damage was visualized through scanning electron microscopy. Enhanced bactericidal activity was demonstrated through this co-delivery of vancomycin and nano-Ag, decreasing the minimum inhibition concentration (MIC) towards E. coli and S. epidermidis down to 15 and 10 µg/mL. This study provides an efficient antimicrobial nano-strategy to address potential bacterial infections.

Breathable, Antibacterial, and Biocompatible Collagen Fiber Network Decorated with Zwitterionic Silver Nanoparticles for Plantar Pressure Monitoring

Foot plantar pressure monitoring and gait analysis are of great significant in footwear design, sport biomechanics, injury prevention, and early warning of disease. Flexible and wearable smart insoles pave a feasible way for these application scenarios. However, the majority of the currently developed smart insoles are composed of synthetic polymers (e.g., plastics, rubbers, etc.), leading to inevitable problems associated with air permeability, hygiene condition, biocompatibility, and wearing comfort. Here, a new paradigm of a natural collagen fiber network (CFN) with soft and breathable features, which can be obtained by facilely treating animal hides via conventional leather pretreatment process, is selected as substrate material for constructing smart insoles due to its high permeability and porosity. Further, biocompatible zwitterionic silver nanoparticles (AgNPs) with both carboxybetaine and catechol groups on the interface were designed for firmly and uniformly immobilization onto the hierarchical micro-/nanoscale fibers of CFN through mussel-inspired catechol/amino chemistry, giving rise to both good antibacterial property and pressure sensing capability of the resultant material. The finally developed smart insole by using the AgNPs decorated CFN exhibits good capability for plantar pressure mapping and gait feature analysis. Especially, the smart insole will be very suitable for pressure monitoring and gait analysis of a diabetic foot with sensitive skin that requires a high biocompatible and antibacterial environment.

Water soluble organometallic small molecules as promising antibacterial agents: synthesis, physical-chemical properties and biological evaluation to tackle bacterial infections

The Na[3,3'-Fe(8-I-1,2-C₂B₉H₁₀)₂] and Na[2,2'-M(1,7-C₂B₉H₁₁)] (M = Co³⁺, Fe³⁺) small molecules are synthesized and the X-ray structures of [(H₃O)(H₂O)₅][2,2'-Co(1,7-C₂B₉H₁₁)₂] and [Cs(MeCN)][8,8'-I₂-Fe(1,2 C₂B₉H₁₀)₂], both displaying a transoid conformation of the [M(C₂B₉)₂]^- framework, are reported. Importantly, the supramolecular structure of [(H₃O)(H₂O)₅][2,2'-Co(1,7-C₂B₉H₁₁)₂] presents 2D layers leading to a lamellar arrangement of the anions while the cation layers form polymeric water rings made of six- and four-membered rings of water molecules connected via OH⋯H hydrogen bonds; B-H⋯O contacts connect the cationic and anionic layers. Herein, we highlight the influence of the ligand isomers (ortho-/meta-), the metal effect (Co³⁺/Fe³⁺) on the same isomer, as well as the influence of the presence of the iodine atoms on the physical-chemical and biological properties of these molecules as antimicrobial agents to tackle antibiotic-resistant bacteria, which were tested with four Gram-positive bacteria, five Gram-negative bacteria, and three Candida albicans strains that have been responsible for human infections. We have demonstrated an antimicrobial effect against Candida species (MIC of 2 and 3 nM for Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂] and Na[2,2'-Co(1,7-C₂B₉H₁₁)₂], respectively), and against Gram-positive and Gram-negative bacteria, including multiresistant MRSA strains (MIC of 6 nM for Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂]). The selectivity index for antimicrobial activity of Na[3,3'-Co(1,2-C₂B₉H₁₁)₂] and Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂] compounds is very high (165 and 1180, respectively), which reveals that these small anionic metallacarborane molecules may be useful to tackle antibiotic-resistant bacteria. Moreover, we have demonstrated that the outer membrane of Gram-negative bacteria constitutes an impermeable barrier for the majority of these compounds. Nonetheless, the addition of two iodine groups in the structure of the parent Na[3,3'-Co(1,2-C₂B₉H₁₁)₂] had an improved effect (3-7 times) against Gram-negative bacteria. Possibly the changes in their physical-chemical properties make the meta-isomers and the ortho-di-iodinated small molecules more permeable for crossing this barrier. It should be emphasized that the most active metallabis(dicarbollide) small molecules are both transoid conformers in contrast to the ortho- [3,3'-Co(1,2-C₂B₉H₁₁)₂]^- that is cisoid. The fact that these small molecules cross the mammalian membrane and have antimicrobial properties but low toxicity for mammalian cells (high selectivity index, SI) represents a promising tool to treat infectious intracellular bacteria. Since there is an urgent need for antibiotic discovery and development, this study represents a relevant advance in the field.

Stimuli-responsive nanoplatforms for antibacterial applications

The continuously increasing bacterial resistance has become a big threat to public health worldwide, which makes it urgent to develop innovative antibacterial strategies. Nanotechnology-based drug delivery systems are considered as promising strategies in combating bacterial infections which are expected to improve the therapeutic efficacy and minimize the side effects. Unfortunately, the conventional nanodrug delivery systems always suffer from practical dilemmas, including incomplete and slow drug release, insufficient accumulation in infected sites, and weak biofilm penetration ability. Stimuli-responsive nanoplatforms are hence developed to overcome the disadvantages of conventional nanoparticles. In this review, we provide an extensive review of the recent progress of endogenous and exogenous stimuli-responsive nanoplatforms in the antibacterial area, including planktonic bacteria, intracellular bacteria, and bacterial biofilms. Taking advantage of the specific infected microenvironment (pH, enzyme, redox, and toxin), the mechanisms and strategies of the design of endogenous stimuli-responsive nanoplatforms are discussed, with an emphasis on how to improve the therapeutic efficacy and minimize side effects. How to realize controlled drug delivery using exogenous stimuli-responsive nanoplatforms especially light-responsive nanoparticles for improved antibacterial effects is another topic of this review. We especially highlight photothermal-triggered drug delivery systems by the combination of photothermal agents and thermo-responsive materials. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nanoantibiotics to fight multidrug resistant infections by Gram-positive bacteria: hope or reality?

The spread of antimicrobial resistance in Gram-positive pathogens represents a threat to human health. To counteract the current lack of novel antibiotics, alternative antibacterial treatments have been increasingly investigated. This review covers the last decade's developments in using nanoparticles as carriers for the two classes of frontline antibiotics active on multidrug-resistant Gram-positive pathogens, i.e., glycopeptide antibiotics and daptomycin. Most of the reviewed papers deal with vancomycin nanoformulations, being teicoplanin- and daptomycin-carrying nanosystems much less investigated. Special attention is addressed to nanoantibiotics used for contrasting biofilm-associated infections. The status of the art related to nanoantibiotic toxicity is critically reviewed.

Functionalization and Antibacterial Applications of Cellulose-Based Composite Hydrogels

Pathogens, especially drug-resistant pathogens caused by the abuse of antibiotics, have become a major threat to human health and public health safety. The exploitation and application of new antibacterial agents is extremely urgent. As a natural biopolymer, cellulose has recently attracted much attention due to its excellent hydrophilicity, economy, biocompatibility, and biodegradability. In particular, the preparation of cellulose-based hydrogels with excellent structure and properties from cellulose and its derivatives has received increasing attention thanks to the existence of abundant hydrophilic functional groups (such as hydroxyl, carboxy, and aldehyde groups) within cellulose and its derivatives. The cellulose-based hydrogels have broad application prospects in antibacterial-related biomedical fields. The latest advances of preparation and antibacterial application of cellulose-based hydrogels has been reviewed, with a focus on the antibacterial applications of composite hydrogels formed from cellulose and metal nanoparticles; metal oxide nanoparticles; antibiotics; polymers; and plant extracts. In addition, the antibacterial mechanism and antibacterial characteristics of different cellulose-based antibacterial hydrogels were also summarized. Furthermore, the prospects and challenges of cellulose-based antibacterial hydrogels in biomedical applications were also discussed.

Low-Molecular-Weight Polylysines with Excellent Antibacterial Properties and Low Hemolysis

The steady development of bacterial resistance has become a global public health issue, and new antibacterial agents that are active against drug-resistant bacteria and less susceptible to bacterial resistance are urgently needed. Here, a series of low-molecular-weight cationic polylysines (C_x-PLL_n) with different hydrophobic end groups (C_x) and degrees of polymerization (PLL_n) was synthesized and used in antibacterial applications. All the obtained C_x-PLL_n have antibacterial activity. Among them, C₆-PLL₁₃ displays the best antibacterial effect for Gram-positive bacteria, that is, Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA), and highest selectivity against Gram-positive bacteria. A mechanistic study revealed that the C₆-PLL₁₃ destroys the integrity of the bacterial cell membrane and causes effective bacterial death. Owing to this membrane-disrupting property, C₆-PLL₁₃ showed rapid bacterial killing kinetics and was not likely to develop resistance after repeat treatment (up to 13 generations). Moreover, C₆-PLL₁₃ demonstrated a significant therapeutic effect on an MRSA infection mouse model, which further proved that this synthetic polymer could be used as an effective weapon against bacterial infections.

Near-infrared light-triggered β-NaYF4:Yb,Tm,Gd@MIL-100(Fe) nanomaterials for antibacterial applications

By inducing a photo-Fenton reaction under 980 nm light irradiation, β-NaYF4:Yb,Tm,Gd@MIL-100(Fe) could generate abundant ROS for antibacterial applications.

Te-Cefotaxime Nanocomposites with Restored Antibiotic Susceptibility and LED Light Activated Photothermal Effect for Rapid MRSA Eradication

The ever-growing antibiotic-resistant bacteria pose a huge threat to public health. Restoring the susceptibility of ineffective antibiotics by inorganic nanomaterials and combining of photothermal and antibiotic synergistic therapy could be...

Glutathione-depletion reinforced enzyme catalytic activity for photothermal assisted bacterial killing by hollow mesoporous CuO

Hollow mesoporous CuO nanozyme with GSH-depletion enhanced the enzyme catalytic activity for photothermal-assisted bacterial killing.

Tertiary Nanosystem Composed of Graphene Quantum Dots, Levofloxacin and Silver Nitrate for Microbiological Control

BACKGROUND

Infectious diseases have the highest mortality rate in the world and these numbers are associated with scarce and/or ineffective diagnosis and bacterial resistance. Currently, with the development of new pharmaceutical formulations, nanotechnology is gaining prominence.

METHODS

Nanomicelles were produced by ultrasonication. The particle size and shape were evaluated by scanning electron microscopy and confirmed by dynamic light scattering, also thermogravimetric analysis was performed to evaluate the thermal stability. Finally, antibacterial activity has been performed.

RESULTS

The results showed that a rod-shaped nanosystem, with 316.1 nm and PDI of 0.243 was formed. The nanosystem was efficient against Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis subsp. spizizenii with MIC inferior to 0.98 and a synergistic effect between silver graphene quantum dots and levofloxacin was observed.

CONCLUSION

The nanosystem produced may rise as a promising agent against the bacterial threat, especially regarding bacterial resistance.

Antimicrobial Activity of Nanoconjugated Glycopeptide Antibiotics and Their Effect on Staphylococcus aureus Biofilm

In the era of antimicrobial resistance, the use of nanoconjugated antibiotics is regarded as a promising approach for preventing and fighting infections caused by resistant bacteria, including those exacerbated by the formation of difficult-to-treat bacterial biofilms. Thanks to their biocompatibility and magnetic properties, iron oxide nanoparticles (IONPs) are particularly attractive as antibiotic carriers for the targeting therapy. IONPs can direct conjugated antibiotics to infection sites by the use of an external magnet, facilitating tissue penetration and disturbing biofilm formation. As a consequence of antibiotic localization, a decrease in its administration dosage might be possible, reducing the side effects to non-targeted organs and the risk of antibiotic resistance spread in the commensal microbiota. Here, we prepared nanoformulations of the 'last-resort' glycopeptides teicoplanin and vancomycin by conjugating them to IONPs via surface functionalization with (3-aminopropyl) triethoxysilane (APTES). These superparamagnetic NP-TEICO and NP-VANCO were chemically stable and NP-TEICO (better than NP-VANCO) conserved the typical spectrum of antimicrobial activity of glycopeptide antibiotics, being effective against a panel of staphylococci and enterococci, including clinical isolates and resistant strains. By a combination of different methodological approaches, we proved that NP-TEICO and, although to a lesser extent, NP-VANCO were effective in reducing biofilm formation by three methicillin-sensitive or resistant Staphylococcus aureus strains. Moreover, when attracted and concentrated by the action of an external magnet, NP-TEICO exerted a localized inhibitory effect on S. aureus biofilm formation at low antibiotic concentration. Finally, we proved that the conjugation of glycopeptide antibiotics to IONPs reduced their intrinsic cytotoxicity toward a human cell line.

Impact of nanomaterials on the intestinal mucosal barrier and its application in treating intestinal diseases

The intestinal mucosal barrier (IMB) is one of the important barriers to prevent harmful substances and pathogens from entering the body environment and to maintain intestinal homeostasis. The dysfunction of the IMB is associated with intestinal diseases and disorders. Nanomaterials have been widely used in medicine and as drug carriers due to their large specific surface area, strong adsorbability, and good biocompatibility. In this review, we comprehensively discuss the impact of typical nanomaterials on the IMB and summarize the treatment of intestinal diseases by using nanomaterials. The effects of nanomaterials on the IMB are mainly influenced by factors such as the dosage, size, morphology, and surface functional groups of nanomaterials. There is huge potential and a broad prospect for the application of nanomaterials in regulating the IMB for achieving an optimal therapeutic effect for antibiotics, oral vaccines, drug carriers, and so on.

Nanoplatforms for Sepsis Management: Rapid Detection/Warning, Pathogen Elimination and Restoring Immune Homeostasis

Sepsis, a highly life-threatening organ dysfunction caused by uncontrollable immune responses to infection, is a leading contributor to mortality in intensive care units. Sepsis-related deaths have been reported to account for 19.7% of all global deaths. However, no effective and specific therapeutic for clinical sepsis management is available due to the complex pathogenesis. Concurrently eliminating infections and restoring immune homeostasis are regarded as the core strategies to manage sepsis. Sophisticated nanoplatforms guided by supramolecular and medicinal chemistry, targeting infection and/or imbalanced immune responses, have emerged as potent tools to combat sepsis by supporting more accurate diagnosis and precision treatment. Nanoplatforms can overcome the barriers faced by clinical strategies, including delayed diagnosis, drug resistance and incapacity to manage immune disorders. Here, we present a comprehensive review highlighting the pathogenetic characteristics of sepsis and future therapeutic concepts, summarizing the progress of these well-designed nanoplatforms in sepsis management and discussing the ongoing challenges and perspectives regarding future potential therapies. Based on these state-of-the-art studies, this review will advance multidisciplinary collaboration and drive clinical translation to remedy sepsis.

Aggregation-Induced Emission-Based Platforms for the Treatment of Bacteria, Fungi, and Viruses

The prevention and control of pathogenic bacteria, fungi, and viruses is a herculean task for all the countries since they greatly threaten global public health. Rapid detection and effective elimination of these pathogens is crucial for the treatment of related diseases. It is urgently demanded to develop new diagnostic and therapeutic strategies to combat bacteria, fungi, and viruses-induced infections. The emergence of aggregation-induced emission (AIE) luminogens (AIEgens) is a revolutionary breakthrough for the treatment of many diseases, including pathogenic infections. In this review, the main focus is on the applications of AIEgens for theranostic treatment of pathogenic bacteria, fungi, and viruses. Due to the AIE characteristic, AIEgens are promising fluorescent probes for the detection of bacteria, fungi, and viruses with excellent sensitivity and photostability. Moreover, AIEgen-based theranostic platforms can be fabricated by introducing bactericidal moieties or designing AIE photosensitizers and AIE photothermal agents. The current strategies and ongoing developments of AIEgens for the treatment of pathogenic bacteria, fungi, and viruses will be discussed in detail.

Physically Switchable Antimicrobial Surfaces and Coatings: General Concept and Recent Achievements

Bacterial environmental colonization and subsequent biofilm formation on surfaces represents a significant and alarming problem in various fields, ranging from contamination of medical devices up to safe food packaging. Therefore, the development of surfaces resistant to bacterial colonization is a challenging and actively solved task. In this field, the current promising direction is the design and creation of nanostructured smart surfaces with on-demand activated amicrobial protection. Various surface activation methods have been described recently. In this review article, we focused on the "physical" activation of nanostructured surfaces. In the first part of the review, we briefly describe the basic principles and common approaches of external stimulus application and surface activation, including the temperature-, light-, electric- or magnetic-field-based surface triggering, as well as mechanically induced surface antimicrobial protection. In the latter part, the recent achievements in the field of smart antimicrobial surfaces with physical activation are discussed, with special attention on multiresponsive or multifunctional physically activated coatings. In particular, we mainly discussed the multistimuli surface triggering, which ensures a better degree of surface properties control, as well as simultaneous utilization of several strategies for surface protection, based on a principally different mechanism of antimicrobial action. We also mentioned several recent trends, including the development of the to-detect and to-kill hybrid approach, which ensures the surface activation in a right place at a right time.

Bioinspired drug delivery strategies for repurposing conventional antibiotics against intracellular infections

Bacteria have developed a wealth of strategies to avoid and resist the action of antibiotics, one of which involves pathogens invading and forming reservoirs within host cells. Due to the poor cell membrane permeability, stability and retention of conventional antibiotics, this renders current treatments largely ineffective, since achieving a therapeutically relevant antibiotic concentration at the site of intracellular infection is not possible. To overcome such challenges, current antibiotics are 'repurposed' via reformulation using micro- or nano-carrier systems that effectively encapsulate and deliver therapeutics across cellular membranes of infected cells. Bioinspired materials that imitate the uptake of biological particulates and release antibiotics in response to natural stimuli are recently explored to improve the targeting and specificity of this 'nanoantibiotic' approach. In this review, the mechanisms of internalization and survival of intracellular bacteria are elucidated, effectively accentuating the current treatment challenges for intracellular infections and the implications for repurposing conventional antibiotics. Key case studies of nanoantibiotics that have drawn inspiration from natural biological particles and cellular uptake pathways to effectively eradicate intracellular pathogens are detailed, clearly highlighting the rational for harnessing bioinspired drug delivery strategies.

Facile Homobifunctional Imidoester Modification of Advanced Nanomaterials for Enhanced Antibiotic Synergistic Effect

Resistance to antibiotics because of misuse and overuse is one of the greatest public health challenges worldwide. Despite the introduction of advanced nanotechnology in the production of antibiotics, the choice of appropriate medicines is limited due to side effects such as blood coagulation, toxicity, low efficacy, and low biocompatibility; therefore, novel nanomaterial composites are required to counter these repercussions. We first introduce a facile method for synthesizing a homobifunctional imidoester-coated nanospindle (HINS) zinc oxide composite for enhancement of antibiotic efficacy and reduction of toxicity and blood coagulation. The antibiotic efficacy of the composites is twice that of commercialized zinc nanoparticles; in addition, they have good biocompatibility, have increased surface charge and solubility owing to the covalent acylation groups of HI, and produce a large number of Zn⁺ ions and defensive reactive oxygen species (ROS) that effectively kill bacteria and fungi. The synergistic effect of a combination therapy with the HINS composite and itraconazole shows more than 90% destruction of fungi in treatments with low dosage with no cytotoxicity or coagulation evident in intravenous administration in in vitro and in vivo experiments. Thus, HINS composites are useful in reducing the effect of misuse and overuse of antibiotics in the medical field.

Stimuli-responsive nanocarriers for bacterial biofilm treatment

ABSTRACT

Bacterial biofilm infections have been threatening the human's life and health globally for a long time because they typically cause chronic and persistent infections. Traditional antibiotic therapies can hardly eradicate biofilms in many cases, as biofilms always form a robust fortress for pathogens inside, inhibiting the penetration of drugs. To address the issues, many novel drug carriers emerged as promising strategies for biofilm treatment. Among them, stimuli-responsive nanocarriers have attracted much attentions for their intriguing physicochemical properties, such as tunable size, shape and surface chemistry, especially smart drug release characteristic. Based on the microenvironmental difference between biofilm infection sites and normal tissue, many stimuli, such as bacterial products accumulating in biofilms (enzymes, glutathione, etc.), lower pH and higher H₂O₂ levels, have been employed and proved in favor of "on-demand" drug release for biofilm elimination. Additionally, external stimuli including light, heat, microwave and magnetic fields are also able to control the drug releasing behavior artificially. In this review, we summarized recent advances in stimuli-responsive nanocarriers for combating biofilm infections, and mainly, focusing on the different stimuli that trigger the drug release.

摘要

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Infection microenvironment-activated nanoparticles for NIR-II photoacoustic imaging-guided photothermal/chemodynamic synergistic anti-infective therapy

Subcutaneous abscesses caused by drug-resistant bacteria pose huge challenges to human health. The design of infection microenvironment-activated biomaterials has an advantage for the diagnosis and treatment of infective diseases due to its high specificity and efficiency. Herein, a novel theranostic platform based on Cu₂O nanoparticles (NPs) is successfully constructed via a simple, fast and low-cost approach. The Cu₂O NPs exhibit high sensitivity to overexpressed H₂S and H₂O₂ in the bacterial infection microenvironment. After in situ injection, the Cu₂O NPs will rapidly react with the endogenous H₂S to generate Cu₉S₈ NPs, which exhibits high absorbance in the second near-infrared (NIR-II) biowindow. The Cu₉S₈ NPs serving as NIR-II photoacoustic contrast agents can exactly distinguish between inflammatory and normal tissues. With the guidance of NIR-II photoacoustic imaging (PAI), H₂S-activated photothermal antibacterial therapy (PTAT) can realize excellent antibacterial performance under 1060 nm laser irradiation. Meanwhile, the Cu₂O NPs can effectively catalyze H₂O₂ at the site of inflammation to produce hydroxyl radicals with strong antibacterial property via Fenton-like reaction, resulting in the damage of bacterial cell membrane. Furthermore, the application of Cu₂O NPs can enhance epidermic migration and facilitate the re-epithelialization of the infected skin. In vivo experiment shows that 97.9% methicillin-resistant Staphylococcus aureus are eliminated by the synergistic PTAT and chemodynamic antibacterial therapy.