Chloride-accelerated Cu-Fenton chemistry for biofilm removal

Accelerated cascade melanoma therapy using enzyme-nanozyme-integrated dissolvable polymeric microneedles

Dissolvable polymeric microneedles (DPMNs) have emerged as a powerful technology for the localized treatment of diseases, such as melanoma. Herein, we fabricated a DPMN patch containing a potent enzyme-nanozyme composite that transforms the upregulated glucose consumption of cancerous cells into lethal reactive oxygen species via a cascade reaction accelerated by endogenous chloride ions and external near-infrared (NIR) irradiation. This was accomplished by combining glucose oxidase (Gox) with a NIR-responsive chloroperoxidase-like copper sulfide (CuS) nanozyme. In contrast with subcutaneous injection, the microneedle system highly localizes the treatment, enhancing nanomedicine uptake by the tumor and reducing its systemic exposure to the kidneys and spleen. NIR irradiation further controls the potency and toxicity of the formulation by thermally disabling Gox. In a mouse melanoma model, this unique combination of photothermal, starvation, and chemodynamic therapies resulted in complete tumor eradication (99.2 ± 0.8 % reduction in tumor volume within 10 d) without producing signs of systemic toxicity. By comparison, other treatment combinations only resulted in a 42-76.5 % reduction in tumor growth. The microneedle patch design is therefore not only highly potent but also with regulated toxicity and improved safety.

Effect of halogenated indoles on biofilm formation, virulence, and root surface colonization by Agrobacterium tumefaciens

Agrobacterium tumefaciens is a plant pathogen that causes crown gall disease in several plant species by transferring its T-DNA to the host genome. Its chemotactic response to a range of chemical compounds released by hosts facilitates its colonization to host surfaces, and thus, novel anti-agrobacterium compounds are needed to prevent its biofilm formation. Here, we investigated 83 indole derivatives against A. tumefaciens, and based on the screening, 4-chloroindole, 6-iodoindole, and 5-chloro-2-methyl indole were selected as candidates that at 50 μg mL^-1 significantly inhibited the adherence and biofilm formation of A. tumefaciens to abiotic (nitrocellulose and polystyrene) and biotic (roots of Brassica juncea) surfaces. Furthermore, they reduced bacterial growth in a time and concentration-dependent manner and significantly reduced log CFU mL^-1 and survival (%). Changes in biofilm morphologies and biomasses, thicknesses, and substratum coverages were determined, and 2-D and 3-D analyses were performed using a crystal violet assay and bright field, CLSM, and SEM microscopies. Virulence factors such as swimming motility, exopolysaccharide, and exo-protease production, and cell surface hydrophobicity were markedly inhibited by the three compounds. Transcriptional analysis showed multi-fold downregulation of biofilm, virulence, motility, and stress-related genes; however, the degrees of these downregulations were variably affected. B. juncea seed germination was only severely affected by 4-chloroindole. This study demonstrates the promising antibiofilm and antivirulence activities of the three indole derivatives tested and their potentials for targeting and curbing A. tumefaciens infections.

Mechanistic insights into enhanced waste activated sludge dewaterability with Cu(II) and Cu(II)/H2O2 treatment: Radical and non-radical pathway

Without extra adjustment of pH, the effects of cupric ions (Cu(II)) and hydrogen peroxide (H₂O₂) alone or in combination on sludge dewatering were studied. It showed good dewatering capability after treated by Cu(II) and Cu(II)/H₂O₂, which indicated by the capillary suction times (CST) decreased from 120.8 ± 4.7 s (control) to about 40 s, and the water content (Wc) of sludge cake dropped by about 10%. The results showed that the extracellular polymeric substances (EPS) were destroyed, which characterized by a significant decrease in the biopolymers' concentrations in tightly-bound EPS. Meanwhile, more rough and porous microstructures and higher zeta potentials were obtained after conditioned. Based on the changes of physicochemical properties of sludge, the variations of EPS, and the identification of reactive species, two distinct mechanisms of improved sludge dewatering were postulated. As for Cu(II) treatment, it was mainly due to the surface charge neutralization, strong cytotoxicity of Cu(I) produced by intracellular reduction of Cu(II), and pH decline caused by Cu(II) hydrolysis that improved sludge dewatering performance, which could be noted as a "non-radical pathway". When in combination with H₂O₂, hydroxyl radicals (·OH) produced by Cu(II)-catalyzed Fenton-like process played a dominant role in degrading sludge flocs and EPS, which could be regarded as a "radical pathway".

Synergistic Multimodal Cancer Therapy Using Glucose Oxidase@CuS Nanocomposites

Multimodal nanotherapeutic cancer treatments are widely studied but are often limited by their costly and complex syntheses that are not easily scaled up. Herein, a simple formulation of glucose-oxidase-coated CuS nanoparticles was demonstrated to be highly effective for melanoma treatment, acting through a synergistic combination of glucose starvation, photothermal therapy, and synergistic advanced chemodynamic therapy enabled by near-infrared irradiation coupled with Fenton-like reactions that were enhanced by endogenous chloride.

Nitrite-enhanced copper-based Fenton reactions for biofilm removal

Unwanted biofilms present challenges for many industries. Herein an innovative biofilm removal technology was developed based on nitrite-accelerated Fenton chemistry, where both dissolved Cu ions and nano-CuO surfaces efficiently generate reactive nitrogen species as disinfectants. This simple, efficient, and cost-effective approach for biofilm removal generates important insights into Fenton chemistry, a fundamental mechanism in nature, considering the ubiquity of copper, hydrogen peroxide, and nitrite in the environment, biological systems, and various industrial processes.

A multifunctional Fenton nanoagent for microenvironment-selective anti-biofilm and anti-inflammatory therapy

Bacterial biofilm infections are intractable to traditional antibiotic treatment and usually cause persistent inflammation. Chemodynamic therapy (CDT) based on the Fenton reaction has recently emerged as a promising anti-biofilm strategy. However, the therapeutic efficacy of current Fenton agents often suffers from inefficient Fenton activity and lacks anti-inflammatory capability. Herein, FePS₃ nanosheets (NSs) are explored for the first time as novel microenvironment-selective therapeutic nanoagents for bacterial biofilm infections with both self-enhanced Fenton activity for an anti-biofilm effect and reactive oxygen species (ROS) scavenging properties for an anti-inflammatory effect. In biofilms with acidic microenvironments, FePS₃ NSs release Fe²⁺ to generate toxic ROS by Fenton reaction and reductive [P₂S₆]^4- to enhance the Fenton activity by reducing Fe³⁺ to Fe²⁺. In the surrounding normal tissues with neutral pH, FePS₃ NSs scavenge ROS by reductive [P₂S₆]^4- with an anti-inflammatory effect. This work demonstrates multifunctional Fenton nanoagents with microenvironment-selective ROS generation and elimination properties for effective treatment of bacterial biofilm infections with both anti-biofilm and anti-inflammatory effects.

Space-Selective Chemodynamic Therapy of CuFe5O8 Nanocubes for Implant-Related Infections

Implant-related infections (IRIs) are a serious complication after orthopedic surgery, especially when a biofilm develops and establishes physical and chemical barriers protecting bacteria from antibiotics and the hosts local immune system. Effectively eliminating biofilms is essential but difficult, as it requires not only breaking the physical barrier but also changing the chemical barrier that induces an immunosuppressive microenvironment. Herein, tailored to a biofilm microenvironment (BME), we proposed a space-selective chemodynamic therapy (CDT) strategy to combat IRIs using metastable CuFe₅O₈ nanocubes (NCs) as smart Fenton-like reaction catalysts whose activity can be regulated by pH and H₂O₂ concentration. In the biofilm, extracellular DNA (eDNA) was cleaved by high levels of hydroxyl radicals (•OH) catalyzed by CuFe₅O₈ NCs, thereby disrupting the rigid biofilm. Outside the biofilm with relatively higher pH and lower H₂O₂ concentration, lower levels of generated •OH effectively reversed the immunosuppressive microenvironment by inducing pro-inflammatory macrophage polarization. Biofilm fragments and exposed bacteria were then persistently eliminated through the collaboration of pro-inflammatory immunity and •OH. The spatially selective activation of CDT and synergistic immunomodulation exerted excellent effects on the treatment of IRIs in vitro and in vivo. The anti-infection strategy is expected to provide a method to conquer IRIs.

Self-targeting, zwitterionic micellar dispersants enhance antibiotic killing of infectious biofilms-An intravital imaging study in mice

Extracellular polymeric substances (EPS) hold infectious biofilms together and limit antimicrobial penetration and clinical infection control. Here, we present zwitterionic micelles as a previously unexplored, synthetic self-targeting dispersant. First, a pH-responsive poly(ε-caprolactone)-block-poly(quaternary-amino-ester) was synthesized and self-assembled with poly(ethylene glycol)-block-poly(ε-caprolactone) to form zwitterionic, mixed-shell polymeric micelles (ZW-MSPMs). In the acidic environment of staphylococcal biofilms, ZW-MSPMs became positively charged because of conversion of the zwitterionic poly(quaternary-amino-ester) to a cationic lactone ring. This allowed ZW-MSPMs to self-target, penetrate, and accumulate in staphylococcal biofilms in vitro. In vivo biofilm targeting by ZW-MSPMs was confirmed for staphylococcal biofilms grown underneath an implanted abdominal imaging window through direct imaging in living mice. ZW-MSPMs interacted strongly with important EPS components such as eDNA and protein to disperse biofilm and enhance ciprofloxacin efficacy toward remaining biofilm, both in vitro and in vivo. Zwitterionic micellar dispersants may aid infection control and enhance efficacy of existing antibiotics against remaining biofilm.

Robust magnetic laccase-mimicking nanozyme for oxidizing o-phenylenediamine and removing phenolic pollutants

In this study, we report a novel magnetic biomimetic nanozyme (Fe₃O₄@Cu/GMP (guanosine 5'-monophosphate)) with high laccase-like activity, which could oxidize toxic o-phenylenediamine (OPD) and remove phenolic compounds. The magnetic laccase-like nanozyme was readily obtained via complexed Cu²⁺ and GMP that grew on the surface of magnetic Fe₃O₄ nanoparticles. The prepared Fe₃O₄@Cu/GMP catalyst could be magnetically recycled for at least five cycles while still retaining above 70% activity. As a laccase mimic, Fe₃O₄@Cu/GMP had more activity and robust stability than natural laccase for the oxidization of OPD. Fe₃O₄@Cu/GMP retained about 90% residual activity at 90°C and showed little change at pH 3-9, and the nanozyme kept its excellent activity after long-term storage. Meanwhile, Fe₃O₄@Cu/GMP had better activity for removing phenolic compounds, and the removal of naphthol was more than 95%. Consequently, the proposed Fe₃O₄@Cu/GMP nanozyme shows potential for use as a robust catalyst for applications in environmental remediation.

A simple and cost-effective approach to fabricate tunable length polymeric microneedle patches for controllable transdermal drug delivery

Polymeric microneedles (MNs) are attractive transdermal drug delivery systems because of their efficient drug delivery and minimal invasiveness. Master template fabrication is the most time-consuming and costly step in producing polymeric MNs using a micromoulding approach. Herein, this issue is addressed by modifying tattoo needle cartridges by adjusting the volume of a PDMS spacer, thus streamlining polymeric MN fabrication and significantly reducing its manufacturing cost. Using the fabricated master template, dissolvable polymeric MN systems containing poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) were developed. This MN system exhibits several advantages, including controllable MN length, uniform distribution of each needle, and controllable drug release profiles. Overall, polymeric MN fabrication using this method is inexpensive, simple, and yields controllable and effective transdermal drug delivery.

A simple and cost-effective approach to fabricate tunable length polymeric microneedle patches for controllable transdermal drug delivery.

Fluoride ion accelerating degradation of organic pollutants by Cu(II)-catalyzed Fenton-like reaction at wide pH range

The degradation of rhodamine B in the F^-/Cu(II)/H₂O₂ system was studied to evaluate the accelerating effect of F^- on the Cu(II)-catalyzed Fenton-like reaction. Effects of various parameters, such as F^-/Cu²⁺ ratio, F^- and Cu²⁺ concentrations, initial pH, temperature, H₂O₂ and rhodamine B concentrations, were investigated. The results confirmed that there is a strong promoting effect of F^- on the Cu(II)-catalyzed Fenton-like reaction in a wide pH range of 4-11. In the F^-/Cu(II)/H₂O₂ system the dye could be degraded quickly, and H₂O₂ had a high utilization. A possible catalytical mechanism was proposed and CuF⁺ was assumed as the catalytically active species. CuF⁺ complexed with the OOH^- produced by H₂O₂ dissociation and then rapidly decomposed to Cu(I), which reacted with H₂O₂ generating hydroxyl radical (HO·), the major reactive oxidizing species.