Nanoarchitectured manganese dioxide (MnO2)-based assemblies for biomedicine

A synergistically antimicrobial and antioxidant hyaluronic acid hydrogel for infected wounds

Bacterial infections during wound healing impede the healing process and trigger local or systemic inflammatory reactions. Consequently, there is an urgent need to develop a new material with antimicrobial and antioxidant properties to promote infected wound healing. A synergistically antimicrobial and antioxidant hyaluronic acid hydrogel (HMn) is prepared by employing MnO2 nanosheets into 4ARM-PEG5000-SH crosslinked methacrylated hyaluronic acid (HAMA) network. The coordination between sulfhydryl groups of 4ARM-PEG5000-SH and MnO2 nanosheets ensures entrapment of the nanosheets within the hydrogel, while the interaction between 4ARM-PEG5000-SH and HAMA results in facile gelation through thiol-ene click reaction. MnO2 nanosheets exhibit strong photothermal properties and reactive oxygen species (ROS) scavenging abilities, while hyaluronic acid promotes wound healing. When subjected to near-infrared (NIR) irradiation, the HMn achieves a bactericidal rate of 95.24 % for Staphylococcus aureus and nearly 100 % for Escherichia coli. In animal experiments, treatment with the HMn under NIR irradiation results in the best wound healing outcomes. Both in vitro and vivo biocompatible assays demonstrate that the HMn has rarely cell cytotoxicity and tissue damage. The HMn is easy to prepare and has good biocompatibility as well as efficient antibacterial and antioxidant properties, providing a novel method for the treatment of infected wounds.

Ultrasound-Triggered Piezoelectric Catalysis of Zinc Oxide@Glucose Derived Carbon Spheres for the Treatment of MRSA Infected Osteomyelitis

Currently, methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis is a clinically life-threatening disease, however, long-term antibiotic treatment can lead to bacterial resistance, posing a huge challenge to treatment and public health. In this study, glucose-derived carbon spheres loaded with zinc oxide (ZnO@HTCS) are successfully constructed. This composite demonstrates the robust ability to generate reactive oxygen species (ROS) under ultrasound (US) irradiation, eradicating 99.788% ± 0.087% of MRSA within 15 min and effectively treating MRSA-induced osteomyelitis infection. Piezoelectric force microscopy tests and finite element method simulations reveal that the ZnO@HTCS composite exhibits superior piezoelectric catalytic performance compared to pure ZnO, making it a unique piezoelectric sonosensitizer. Density functional theory calculations reveal that the formation of a Mott-Schottky heterojunction and an internal piezoelectric field within the interface accelerates the electron transfer and the separation of electron-hole pairs. Concurrently, surface vacancies of the composite enable the adsorption of a greater amount of oxygen, enhancing the piezoelectric catalytic effect and generating a substantial quantity of ROS. This work not only presents a promising approach for augmenting piezoelectric catalysis through construction of a Schottky heterojunction interface but also provides a novel, efficient therapeutic strategy for treating osteomyelitis.

A carbon dots-MnO2 nanosheet-based turn-on pseudochemodosimeter as low-cost probe for selective detection of hazardous mercury ion contaminations in water

Mercury is a highly hazardous element due to its profound toxicity and wide abundance in the environment. Despite the availability of various fluorimetric detection tools for Hg2+, including organic fluorophores and aptasensors, they often suffer from shortcomings like the utilization of expensive chemicals and toxic organic solvents, multi-step synthesis, sometimes with poor selectivity and low sensitivity. Whereas, biomass-derived fluorophores, such as carbon dots (CDs), present themselves as cost-effective and environmentally benign alternatives that exhibit comparable efficacy. Herein, we report a reaction-driven sensing assembly based on CDs, MnO2 nanosheets, and hydroquinone monothiocarbonate (HQTC) for the detection of Hg2+ ions, which relies on the formation of a CDs-MnO2 FRET-conjugate, resulting in the quenching of the intrinsic fluorescence of CDs. In a pseudochemodosimetric approach, the thiophilic nature of mercury was utilized for in-situ generation of the reducing species, hydroquinone from HQTC, resulting in the reduction of MnO2 nanosheets, the release of fluorescent CDs back to the solution. The low limit of detection (LOD) was achieved as 2 ppb (0.01 μM). The probe worked efficiently in real water samples like sea, river with good recovery of spiked Hg2+ and in some Indian ayurvedic medicines as well. Furthermore, solid-phase detection with sodium alginate beads demonstrated the ability of this cost-effective sensing assembly for onsite detection of Hg2+ ions.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Trinity Strategy: Enabling Perovskite as Hydrophilic and Efficient Fluorescent Nanozyme for Constructing Biomarker Reporting Platform

Water instability and sensing homogeneity are the Achilles' heel of CsPbX3 NPs in biological fluids application. This work reports the preparation of Mn2+:CsPbCl3@SiO2 yolk-shell nanoparticles (YSNPs) in aqueous solutions created through the integration of ligand, surface, and crystal engineering strategies. The SN2 reaction between 4-chlorobutyric acid (CBA) and oleylamine (OAm) yields a zwitterionic ligand that facilitates the dispersion of YSNPs in water, while the robust SiO2 shell enhances their overall stability. Besides, Mn2+ doping in YSNPs not only introduces a second emission center but also enables potential postsynthetic designability, leading to the switching from YSNPs to MnO2@YSNPs with excellent oxidase (OXD)-like activity. Theoretical calculations reveal that electron transfer from CsPbCl3 to in situ MnO2 and the adsorption-desorption process of 3,3',5,5'-tetramethylbenzidine (TMB) synergistically amplify the OXD-like activity. In the presence of ascorbic acid (AA), Mn4+ in MnO2@YSNPs (fluorescent nanozyme) is reduced to Mn2+ and dissociated, thereby inhibiting the OXD-like activity and triggering fluorescence "turn-on/off", i.e., dual-mode recognition. Finally, a biomarker reporting platform based on MnO2@YSNPs fluorescent nanozyme is constructed with AA as the reporter molecule, and the accurate detection of human serum alkaline phosphatase (ALP) is realized, demonstrating the vast potential of perovskites in biosensing.

Ultra-efficient radio-immunotherapy for reprogramming the hypoxic and immunosuppressive tumor microenvironment with durable innate immune memory

Radiosensitization efficacy of conventional tumor radiosensitizers has been frequently limited by insufficient competence for tumor microenvironment (TME) regulation and unfavorable cellular uptake at biological barriers. Here, we reported an ultra-efficient radiotherapy (RT) strategy by synthesizing an extracellular vesicles (EVs)-encapsulated hollow MnO2 to load metformin (Met@HMnER). It demonstrated significant RT enhancement by morphological control of catalyst and cellular respiratory depression against conventional solid MnO2. Furthermore, the target-modified EVs clothing retains outstanding metformin loading capacity while endowing enhanced biological barrier penetration. A noticeably durable innate immune activation of NK cells was triggered with this nanoplatform via the cGAS-STING pathway. The enhanced immunocompetence was verified on distal metastasis and in-situ recurrence model in vivo, This work paved a new path for synergistic and robust innate immunity in clinical cancer treatment.

NIR-switchable local hydrogen generation by tandem bimetallic MOFs nanocomposites for enhanced chemodynamic therapy

The inadequate quantity of hydrogen peroxide (H2O2) in cancer cells promptly results in the constrained success of chemodynamic therapy (CDT). Significant efforts made throughout the years; nevertheless, researchers are still facing the great challenge of designing a CDT agent and securing H2O2 supply within the tumor cell. In this study, taking advantage of H2O2 level maintenance mechanism in cancer cells, a nanozyme-based bimetallic metal-organic frameworks (MOFs) tandem reactor is fabricated to elevate intracellular H2O2 levels, thereby enhancing CDT. In addition, under near-infrared excitation, the upconversion nanoparticles (UCNPs) loaded into the MOFs can perform photocatalysis and generate hydrogen, which increases cellular susceptibility to radicals induced from H2O2, inhibits cancer cell energy, causes DNA damages and induces tumor cell apoptosis, thus improving CDT therapeutic efficacy synergistically. The proposed nanozyme-based bimetallic MOFs-mediated CDT and UCNPs-mediated hydrogen therapy act as combined therapy with high efficacy and low toxicity.

Self-template sacrifice and in situ oxidation of a constructed hollow MnO2 nanozymes for smartphone-assisted colorimetric detection of liver function biomarkers

Liver function tests play a vital role in accurately diagnosing liver diseases, monitoring treatment outcomes, and assessing liver damage severity. Here, we introduce a novel approach to develop a smartphone-assisted portable colorimetric sensor for rapid detection of three liver function biomarkers: aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). This sensor is based on the inherent enzyme-like activities of hollow MnO2 (H-MnO2). The H-MnO2 is synthesized via a self-template sacrifice and in situ oxidation strategy, utilizing a manganese-based Prussian blue analogue (Mn-PBA) as a sacrificial template. The resulting H-MnO2 exhibits a polycrystalline structure with a large specific surface area. By encapsulating the H-MnO2 in sodium alginate, we construct a portable sensing platform facilitating specific and rapid colorimetric detection of the three liver function biomarkers with the assistance of a smartphone. The developed sensor demonstrates outstanding sensitivity and stability, achieving detection limits of 4.9 U L-1, 3.6 U L-1, and 0.99 U L-1 for AST, ALT, and ALP, respectively. Importantly, this work introduces an innovative in situ oxidation method for fabricating hollow nanozymes, offering a cost-effective and convenient assay for liver function biomarkers detection.

A "Chase and Block" Strategy for Enhanced Cancer Therapy with Hypoxia-Promoted Photodynamic Therapy and Autophagy Inhibition Based on Upconversion Nanocomposites

The combination of hypoxia-promoted photodynamic therapy (PDT) and autophagy modulation has shown strong potential in the treatment of hypoxic tumors. Here, a novel design is put forward for synergistic PDT and autophagy inhibition to amplify the effect of cancer therapy by a "chase and block" strategy. Specifically, the organic photosensitive molecule (denoted FL) is encapsulated in a hydrophobic layer between multi-band emitted upconversion nanoparticles (UCNPs) and the amphiphilic polymer DSPE-PEG-COOH, allowing FL to fully exploit the luminescence spectrum of UCNPs under near-infrared (NIR) light irradiation. The FL is specifically activated by nitroreductase in the tumor microenvironment (TME), enabling hypoxia-promoted PDT and thus performing a "chase" strategy for cancer therapy. Additionally, the nanosystem is combined with an autophagy-inhibiting melittin pro-peptide (denoted as MEL), which could be triggered by the highly expressed legumain in tumor cells to inhibit the autophagy procedure by disrupting the lysosomal membrane, thus "blocking" the cancer cells from rescuing themselves and amplifying the killing effect of PDT. Both FL and MEL can be specifically activated by TME and the upconversion luminescence imaging of UCNPs offers a tracer function for the treatment. Therefore, UCNPs@FL-MEL might be an important reference for the design and development of future nanotherapeutic agents.

MnO2 nanosheets and gold nanoparticles supported electrochemical detection of circulating tumor cells

The concentration of circulating tumor cells (CTCs) in peripheral blood is strongly correlated with the progress of certain metastatic cancers. In this study, we have developed a novel and facile electrochemical biosensor for the detection of CTCs based on the use of manganese dioxide nanosheets (MnO2 NSs) and gold nanoparticles (AuNPs). Aptamer sequence of target cell is modified on the surface of AuNPs for specifical recognition. With low-speed centrifugation, numerous AuNPs@DNA can be removed from the supernatant. On the other hand, MnO2 NSs are modified on the electrode surface to capture unreacted AuNPs@DNA. The declined electrochemical signal intensity can be used to reflect the level of CTCs. This biosensor achieves a wide linear range from 10 to 104 cells mL-1 and a limit of detection as low as 3 cells mL-1. Due to the specific aptamer as the recognition element, interfering cells can be successfully distinguished and this method performs satisfactorily in clinical samples. Therefore, it has great potential to be used as a powerful tool benefiting rare cells analysis and the investigation of dynamics of cellular interactions.

Preparation of Biocompatible Manganese Selenium-Based Nanoparticles with Antioxidant and Catalytic Functions

The specificity of the tumor microenvironment (TME) severely limits the effectiveness of tumor treatment. In this study, we prepared a composite nanoparticle of manganese dioxide and selenite by a one-step redox method, and their stability under physiological conditions was improved with a bovine serum protein modification to obtain MnO₂/Se-BSA nanoparticles (SMB NPs). In the SMB NPs, manganese dioxide and selenite endowed the SMB NPs with acid-responsive and catalytic, and antioxidant properties, respectively. The weak acid response, catalytic activity, and antioxidant properties of composite nanoparticles were verified experimentally. Moreover, in an in vitro hemolysis assay, different concentrations of nanoparticles were incubated with mouse erythrocytes, and the hemolysis ratio was less than 5%. In the cell safety assay, the cell survival ratio was as high as 95.97% after the co-culture with L929 cells at different concentrations for 24 h. In addition, the good biosafety of composite nanoparticles was verified at the animal level. Thus, this study helps to design high-performance and comprehensive therapeutic reagents that are responsive to the hypoxia, weak acidity, hydrogen peroxide overexpression nature of TME and overcome the limitations of TME.

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

Overcoming Cancer Multi-drug Resistance (MDR): Reasons, mechanisms, nanotherapeutic solutions, and challenges

Multi-drug resistance (MDR) in cancer cells, either intrinsic or acquired through various mechanisms, significantly hinders the therapeutic efficacy of drugs. Typically, the reduced therapeutic performance of various drugs is predominantly due to the inherent over expression of ATP-binding cassette (ABC) transporter proteins on the cell membrane, resulting in the deprived uptake of drugs, augmenting drug detoxification, and DNA repair. In addition to various physiological abnormalities and extensive blood flow, MDR cancer phenotypes exhibit improved apoptotic threshold and drug efflux efficiency. These severe consequences have substantially directed researchers in the fabrication of various advanced therapeutic strategies, such as co-delivery of drugs along with various generations of MDR inhibitors, augmented dosage regimens and frequency of administration, as well as combinatorial treatment options, among others. In this review, we emphasize different reasons and mechanisms responsible for MDR in cancer, including but not limited to the known drug efflux mechanisms mediated by permeability glycoprotein (P-gp) and other pumps, reduced drug uptake, altered DNA repair, and drug targets, among others. Further, an emphasis on specific cancers that share pathogenesis in executing MDR and effluxed drugs in common is provided. Then, the aspects related to various nanomaterials-based supramolecular programmable designs (organic- and inorganic-based materials), as well as physical approaches (light- and ultrasound-based therapies), are discussed, highlighting the unsolved issues and future advancements. Finally, we summarize the review with interesting perspectives and future trends, exploring further opportunities to overcome MDR.

Formulation and clinical advancement of nanourchins: a novel multibranched nanoparticulate drug-delivery system

Nanourchins are multibranched nanoparticles with unique optical properties and surface spikes. Because of their unique properties, gold nanourchins have advantages over gold nanoparticles. The most used nanourchins are gold, tungsten, carbon, vanadium and sea urchins. The synthesis of various nanourchins and their clinical advancement are discussed in this review. ZFNs, TALENs and CRISPR/Cas9 are discussed to facilitate understanding of advancements in nanourchins. Nanourchins have been studied for Parkinson's disease, Alzheimer's disease and bioimaging. The synthesis of molybdenum diselenide nanourchins and their bioconjugations are also discussed. Nanourchins can be further explored to improve drug targeting and delivery. Researchers from several fields may contribute to the study of nanourchins as prospective nanocarriers with target specificity.