Manganese oxide nanomaterials for bacterial infection detection and therapy

Biomedical applications of stimuli-responsive nanomaterials

Nanomaterials have aroused great interests in drug delivery due to their nanoscale structure, facile modifiability, and multifunctional physicochemical properties. Currently, stimuli-responsive nanomaterials that can respond to endogenous or exogenous stimulus display strong potentials in biomedical applications. In comparison with conventional nanomaterials, stimuli-responsive nanomaterials can improve therapeutic efficiency and reduce the toxicity of drugs toward normal tissues through specific targeting and on-demand drug release at pathological sites. In this review, we summarize the responsive mechanism of a variety of stimulus, including pH, redox, and enzymes within pathological microenvironment, as well as exogenous stimulus such as thermal effect, magnetic field, light, and ultrasound. After that, biomedical applications (e.g., drug delivery, imaging, and theranostics) of stimuli-responsive nanomaterials in a diverse array of common diseases, including cardiovascular diseases, cancer, neurological disorders, inflammation, and bacterial infection, are presented and discussed. Finally, the remaining challenges and outlooks of future research directions for the biomedical applications of stimuli-responsive nanomaterials are also discussed. We hope that this review can provide valuable guidance for developing stimuli-responsive nanomaterials and accelerate their biomedical applications in diseases diagnosis and treatment.

Pt-Ru bimetallic nanoclusters with peroxidase-like activity for antibacterial therapy

Drug-resistant bacteria arising from antibiotic abuse infections have always been a serious threat to human health. Killing bacteria with toxic reactive oxygen species (ROS) is an ideal antibacterial method for treating drug-resistant bacterial infections. Here, we prepared Pt-Ru bimetallic nanoclusters (Pt-Ru NCs) with higher peroxidase (POD)-like activity than Pt monometallic nanoclusters. Pt-Ru can easily catalyze the decomposition of H2O2 to produce ·OH, thereby catalyzing the transformation of 3,3',5,5'-tetramethylbiphenylamine (TMB) to blue oxidized TMB (oxTMB). We utilized the POD-like activity of the Pt-Ru NCs for antibacterial therapy. The results showed that at doses of 40 μg/mL and 16 μg/mL, the Pt-Ru NCs exhibited extraordinary antibacterial activity against E. coli and S. aureus, demonstrating the enormous potential of Pt-Ru NCs as antibacterial agents.

Tumor microenvironment responsive nano-platform for overcoming sorafenib resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor, which seriously jeopardizes human health. The 5-year relative survival rate of HCC is only about 18%. Sorafenib, a small molecule multi-targeted tyrosine kinase inhibitor (MTKI), has been classified as the first-line treatment scheme for HCC and has significantly extended the median survival time for patients with advanced HCC. Nevertheless, the emergence of sorafenib resistance has substantially hampered its further clinical application. Herein, the nano-platform based on phototherapy and small molecular targeted therapy (SMTT) was devised to overcome the sorafenib resistance and reduce the adverse effects. Hollow mesoporous manganese dioxide (H-MnO2) was prepared by hard template method, and the prepared H-MnO2 was used to load sorafenib and Chlorin e6 (Ce6). Subsequently, the nanoparticle (NPs) were modified with dopamine to optimize biocompatibility. The final prepared NPs (MCS NPs) exhibit regular spherical shape with a hydrated particle size of approximately 97.02 nm. MCS NPs can not only possess tumor microenvironment (TME) stimuli-responsive drug release performance but also can enhance the efficacy of photodynamic therapy and reverse sorafenib resistance by alleviating tumor hypoxia. Under the action of phototherapy (Ce6) combined with molecular targeted therapy (sorafenib), MCS NPs manifest a satisfactory antitumor effect for sorafenib-sensitive or sorafenib-resistant HCC cells, and retain the antiangiogenic properties of sorafenib. In the nude mouse subcutaneous tumor model constructed with sorafenib-resistant cells, MCS NPs demonstrated superior tumor imaging ability and excellent biocompatibility. The tumor inhibition rate of the MCS NPs group without laser irradiation was 53.4 %, while the MCS NPs group with laser irradiation was as high as 100 %. The novel smart TME-responsive nano-platform shows great potential for overcoming sorafenib resistance and realizes multimodality imaging and therapy of HCC.

Characterization and Cellular Toxicity Studies of Commercial Manganese Oxide Nanoparticles

Manganese oxide nanoparticles (MnOx NPs) are finding applications in several environmentally important areas such as farming and energy storage. MnOx NPs span a range of metal oxidation states that open up a wide range of applications in catalysis as well. As a result, it is important to understand how such materials can impact human health through incidental exposure. In this study, we examined a range of commercially available Mn2O3 NPs and compared our characterization data to those supplied by manufacturers. Discrepancies were noted and then measured values were used to assess the biological impact of these materials on three mammalian cell lines-A549, HepG2 and J774A.1 cells. Cell toxicity assays showed that all Mn2O3 particles exhibited cytotoxic effects that may be correlated, at least in part, to the production of reactive oxygen species. All eight nanoforms also activated caspase 3 but not caspase 1, although the magnitude of these changes varied greatly between materials.

Research progress in green synthesis of manganese and manganese oxide nanoparticles in biomedical and environmental applications - A review

Nanomaterials and nanotechnology have this unassailable position for environmental remediation and medicine. Currently, global environmental pollution and public health problems are increasing and need to be urgently addressed. Manganese (Mn) is one of the essential metal elements for plants and animals, it is necessary to integrate with nanotechnology. Mn and Mn oxide (MnO) nanoparticles (NPs) have applications in dye degradation, biomedicine, electrochemical sensors, plant and animal growth, and catalysis. However, the current research is limited, especially in terms of optimal synthesis of Mn and MnO NPs, separation, purification conditions, and the development of potential application areas is too basic and do not support by in-depth studies. Hence, this review comprehensively discusses the classification, green synthesis methods, and applications of Mn and MnO NPs in biomedical, environmental, and other fields and gives a perspective for the future.

Advances in image-guided drug delivery for antibacterial therapy

The emergence of antibiotic-resistant bacterial strains is seriously endangering the global healthcare system. There is an urgent need for combining imaging with therapies to realize the real-time monitoring of pathological condition and treatment progress. It also provides guidance on exploring new medicines and enhance treatment strategies to overcome the antibiotic resistance of existing conventional antibiotics. In this review, we provide a thorough overview of the most advanced image-guided approaches for bacterial diagnosis (e.g., computed tomography imaging, magnetic resonance imaging, photoacoustic imaging, ultrasound imaging, fluorescence imaging, positron emission tomography, single photon emission computed tomography imaging, and multiple imaging), and therapies (e.g., photothermal therapy, photodynamic therapy, chemodynamic therapy, sonodynamic therapy, immunotherapy, and multiple therapies). This review focuses on how to design and fabricate photo-responsive materials for improved image-guided bacterial theranostics applications. We present a potential application of different image-guided modalities for both bacterial diagnosis and therapies with representative examples. Finally, we highlighted the current challenges and future perspectives image-guided approaches for future clinical translation of nano-theranostics in bacterial infections therapies. We envision that this review will provide for future development in image-guided systems for bacterial theranostics applications.

Advances of MnO2 nanomaterials as novel agonists for the development of cGAS-STING-mediated therapeutics

As an essential micronutrient, manganese plays an important role in the physiological process and immune process. In recent decades, cGAS-STING pathway, which can congenitally recognize exogenous and endogenous DNA for activation, has been widely reported to play critical roles in the innate immunity against some important diseases, such as infections and tumor. Manganese ion (Mn²⁺) has been recently proved to specifically bind with cGAS and activate cGAS-STING pathway as a potential cGAS agonist, however, is significantly restricted by the low stability of Mn²⁺ for further medical application. As one of the most stable forms of manganese, manganese dioxide (MnO₂) nanomaterials have been reported to show multiple promising functions, such as drug delivery, anti-tumor and anti-infection activities. More importantly, MnO₂ nanomaterials are also found to be a potential candidate as cGAS agonist by transforming into Mn²⁺, which indicates their potential for cGAS-STING regulations in different diseased conditions. In this review, we introduced the methods for the preparation of MnO₂ nanomaterials as well as their biological activities. Moreover, we emphatically introduced the cGAS-STING pathway and discussed the detailed mechanisms of MnO₂ nanomaterials for cGAS activation by converting into Mn²⁺. And we also discussed the application of MnO₂ nanomaterials for disease treatment by regulating cGAS-STING pathway, which might benefit the future development of novel cGAS-STING targeted treatments based on MnO₂ nanoplatforms.

"Self-Defensive" Antifouling Zwitterionic Hydrogel Coatings on Polymeric Substrates

In biomedicine fields, biofouling can easily occur on devices such as sensors and catheters, causing some iatrogenic infections, which menace the lives and health of patients greatly. Therefore, it is of great significance to solve the problems of bacterial infection on the surfaces of medical devices. In this paper, "self-defensive" and antifouling zwitterionic hydrogel coatings were prepared by network interpenetration of the hydrogel and the polymeric substrates. The zwitterionic polysulfobetaine methacrylate (PSBMA) hydrogel coatings resisted most of the bacteria to adhere on the substrates. When a few bacteria were lucky to escape the antifouling defense and adhered to the coatings, gentamicin sulfate (GS) would be released under the trigger of a weakly acidic environment caused by bacterial metabolism to kill these bacteria. Simultaneously, the coatings of the bacteria-adhering sites would be degraded by hyaluronidase secreted by these bacteria and peeled off to remove the bacteria and renew the antifouling surfaces. The antifouling properties and mechanism of the self-defensive behavior of the hydrogel coatings on polymeric substrates were investigated. Furthermore, the in vitro and in vivo antibacterial performances, as well as the biocompatibility of the coatings, were demonstrated. The results suggested that the self-defensive antifouling zwitterionic hydrogel coatings hold great potential to be used on the surfaces of polymeric medical devices.

Multi-target tyrosine kinase inhibitor nanoparticle delivery systems for cancer therapy

Multi-target Tyrosine Kinase Inhibitors (MTKIs) have drawn substantial attention in tumor therapy. MTKIs could inhibit tumor cell proliferation and induce apoptosis by blocking the activity of tyrosine kinase. However, the toxicity and drug resistance of MTKIs severely restrict their further clinical application. The nano pharmaceutical technology based on MTKIs has attracted ever-increasing attention in recent years. Researchers deliver MTKIs through various types of nanocarriers to overcome drug resistance and improve considerably therapeutic efficiency. This review intends to summarize comprehensive applications of MTKIs nanoparticles in malignant tumor treatment. Firstly, the mechanism and toxicity were introduced. Secondly, various nanocarriers for MTKIs delivery were outlined. Thirdly, the combination treatment schemes and drug resistance reversal strategies were emphasized to improve the outcomes of cancer therapy. Finally, conclusions and perspectives were summarized to guide future research.

Immunotherapy-based novel nanoparticles in the treatment of gastrointestinal cancer: Trends and challenges

Gastrointestinal cancer (GIC) is the most common cancer with a poor prognosis. Currently, surgery is the main treatment for GIC. However, the high rate of postoperative recurrence leads to a low five-year survival rate. In recent years, immunotherapy has received much attention. As the only immunotherapy drugs approved by the Food and Drug Administration (FDA), immune checkpoint blockade (ICB) drugs have great potential in cancer therapy. Nevertheless, the efficacy of ICB treatment is greatly limited by the low immunogenicity and immunosuppressive microenvironment of GIC. Therefore, the targets of immunotherapy have expanded from ICB to increasing tumor immunogenicity, increasing the recruitment and maturation of immune cells and reducing the proportion of inhibitory immune cells, such as M2-like macrophages, regulatory T cells and myeloid-derived suppressor cells. Moreover, with the development of nanotechnology, a variety of nanoparticles have been approved by the FDA for clinical therapy, so novel nanodrug delivery systems have become a research focus for anticancer therapy. In this review, we summarize recent advances in the application of immunotherapy-based nanoparticles in GICs, such as gastric cancer, hepatocellular carcinoma, colorectal cancer and pancreatic cancer, and described the existing challenges and future trends.

Application of nanotechnology in the diagnosis and treatment of acute pancreatitis

Acute pancreatitis (AP) is a common digestive system disease. The severity of AP ranges from mild edema in the pancreas to severe systemic inflammatory responses leading to peripancreatic/pancreatic necrosis, multi-organ failure and death. Improving the sensitivity of AP diagnosis and developing alternatives to traditional methods to treat AP have gained the attention of researchers. With the continuous rise of nanotechnology, it is being widely used in daily life, biomedicine, chemical energy and many other fields. Studies have demonstrated the effectiveness of nanotechnology in the diagnosis and treatment of AP. Nanotechnology has the advantages of simplicity, rapidity and sensitivity in detecting biomarkers of AP, as well as enhancing imaging, which helps in the early diagnosis of AP. On the other hand, nanoparticles (NPs) have oxidative stress inhibiting and anti-inflammatory effects, and can also be loaded with drugs as well as being used in anti-infection therapy, providing a new approach for the treatment of AP. In this article, we elaborate and summarize on the potential of nanoparticles for diagnostic and therapeutic applications in AP from the current reported literature and experimental results to provide useful guidelines for further research on the application of nanotechnology.

Nanomaterials based on phase change materials for antibacterial application

This review presented the applications of PCM-based nanomaterials in bacterial infections. Firstly, the composition and biotoxicity were outlined. Secondly, various antibacterial tactics were highlighted. Lastly, the perspectives were discussed.

A self-activated cascade nanoreactor based on Pd-Ru/GOx for bacterial infection treatment

Enzyme cascade reaction that integrated nature enzyme and nanozyme has attracted intensive attention in biomedical studies. Nevertheless, it is still an important challenge to design simple, high-performance and safe cascade...