Blended gold/MnO2@BSA nanoparticles for fluorometric and magnetic resonance determination of ascorbic acid

Hydrangea-like TiO2/Bi2MoO6 porous nanoflowers triggering highly sensitive electrochemical immunosensing to tumor marker

Rapid and sensitive detection of carcinoembryonic antigen (CEA) is of great significance for cancer patients. Here, molybdenum (Mo) was doped into bismuth oxide (Bi2O3) by one-pot hydrothermal method forming porous tremella Bi2MoO6 nanocomposites with a larger specific surface area than the spherical structure. Then, a new kind of hydrangea-like TiO2/Bi2MoO6 porous nanoflowers (NFs) was prepared by doping titanium into Bi2MoO6, where titanium dioxide (TiO2) grew in situ on the surface of Bi2MoO6 nanoparticles (NPs). The hydrangea-like structure provides larger specific surface area, higher electron transfer ability and biocompatibility as well as more active sites conducive to the attachment of anti-carcinoembryonic antigen (anti-CEA) to TiO2/Bi2MoO6 NFs. A novel label-free electrochemical immunosensor was then constructed for the quantitative detection of CEA using TiO2/Bi2MoO6 NFs as sensing platform, showing a good linear relationship with CEA in the concentration range 1.0 pg/mL ~ 1.0 mg/mL and a detection limit of 0.125 pg/mL (S/N = 3). The results achieved with the designed immunosensor are comparable with many existing immunosensors used for the detection of CEA in real samples.

Construction of a Functional Nucleic Acid-Based Artificial Vesicle-Encapsulated Composite Nanoparticle and Its Application in Retinoblastoma-Targeted Theranostics

Retinoblastoma (RB) is an aggressive tumor of the infant retina. However, the ineffective targeting of its theranostic agents results in poor imaging and therapeutic efficacy, which makes it difficult to identify and treat RB at an early stage. In order to improve the imaging and therapeutic efficacy, we constructed an RB-targeted artificial vesicle composite nanoparticle. In this study, the MnO2 nanosponge (hMNs) was used as the core to absorb two fluorophore-modified DNAzymes to form the Dual/hMNs nanoparticle; after loaded with the artificial vesicle derived from human red blood cells, the RB-targeted DNA aptamers were modified on the surface, thus forming the Apt-EG@Dual/hMNs complex nanoparticle. The DNA aptamer endows this nanoparticle to target the nucleolin-overexpressed RB cell membrane specifically and enters cells via endocytosis. The nanoparticle could release fluorophore-modified DNAzymes and supplies Mn2+ as a DNAzyme cofactor and a magnetic resonance imaging (MRI) agent. Subsequently, the DNAzymes can target two different mRNAs, thereby realizing fluorescence/MR bimodal imaging and dual-gene therapy. This study is expected to provide a reliable and valuable basis for ocular tumor theranostics.

Immunochromatographic Assay based on Sc-TCPP 3D MOF for the rapid detection of imidacloprid in food samples

In this work, a highly sensitive immunochromatographic test strip (ITS) based on Scandium-Tetrakis (4-carboxyphenyl) porphyrin (TCPP) metal-organic framework nanocubes (ScTMNs) was developed for ultrasensitive and facile visual determination of imidacloprid (IDP). TCPP as the porphyrin-based planar ligand and Sc³⁺ as the metal center were applied to form the ScTMNs via coordination chelation. Giving the credit to its excellent optical characteristics, strong affinity with monoclonal antibodies, and favorable biocompatibility, the ScTMNs was selected as a signal tag. Under optimized conditions, the ITS exhibited a great liner relationship in the range of 0.04-3 ng/mL and the detection limit was 0.04 ng/mL for the IDP detection. Additionally, IDP was successfully detected in tomatoes, millet, corn and carrot samples with satisfied recoveries. To the best of our knowledge, this is the first time that ScTMNs have been used in immunochromatography which are expected to have potential applications in detection of other substances.

Facile Synthesis of Multifunctional Magnetoplasmonic Au-MnO Hybrid Nanocomposites for Cancer Theranostics

Significant attention is paid to the design of magnetoplasmonic nanohybrids, which exploit synergistic properties for biomedical applications. Here, a facile method was employed to prepare plasmonic magnetic Au-MnO heterostructured hybrid nanoparticles for imaging-guided photothermal therapy of cancers in vitro, with the view to reducing the serious drawbacks of chemotherapy and gadolinium-based contrast agents. The biocompatibility of the prepared Au-MnO nanocomposites was further enhanced by Food and Drug Administration (FDA)-approved triblock copolymers Pluronic^® F-127 and chitosan oligosaccharide (COS), with complementary support to enhance the absorption in the near-infrared (NIR) region. In addition, synthesized COS-PF127@Au-MnO nanocomposites exhibited promising contrast enhancement in T₁ MR imaging with a good r₁ relaxivity value (1.2 mM^-1 s^-1), demonstrating a capable substitute to Gd-based toxic contrast agents. In addition, prepared COS-PF127@Au-MnO hybrid nanoparticles (HNPs) produced sufficient heat (62 °C at 200 μg/mL) to ablate cancerous cells upon 808 nm laser irradiation, inducing cell toxicity, and apoptosis. The promising diagnostic and photothermal therapeutic performance demonstrated the appropriateness of the COS-PF127@Au-MnO HNPs as a potential theranostic agent.

Biomimetic radiosensitizers unlock radiogenetics for local interstitial radiotherapy to activate systematic immune responses and resist tumor metastasis

Background

Similar to other local therapeutic methods, local interstitial radiotherapy (IRT) also suffers from insufficient systematic immune activation, resulting in tumor metastasis.

Results

Mn-based IRT radiosensitizers consisting of ¹³¹I, MnO₂ and bovine serum albumin (BSA) (¹³¹I-MnO₂-BSA) were engineered. Such Mn-based IRT radiosensitizers successfully unlocked radiogenetics to magnify systematic immune responses of local IRT via remodeling hypoxic and immunosuppressive microenvironments and resist tumor metastasis. The MnO₂ in ¹³¹I-MnO₂-BSA caused decomposition of H₂O₂ enriched in tumors to generate O₂ for alleviating hypoxic microenvironment and removing tumor resistances to IRT. Concurrently, hypoxia mitigation by such radiosensitizers-unlocked radiogenetics can effectively remodel immunosuppressive microenvironment associated with regulatory T (Treg) cells and tumor-associated macrophages (TAMs) infiltration inhibition to induce immunogenic cell death (ICD), which, along with hypoxia mitigation, activates systematic immune responses. More intriguingly, ¹³¹I-MnO₂-BSA-enabled radiogenetics can upregulate PD-L1 expression, which allows anti-PD-L1-combined therapy to exert a robust antitumor effect on primary tumors and elicit memory effects to suppress metastatic tumors in both tumor models (4T1 and CT26).

Conclusions

IRT radiosensitizer-unlocked radiogenetics and the corresponding design principle provide a general pathway to address the insufficient systematic immune responses of local IRT.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01324-w.

Perfluorooctyl bromide nanoemulsions holding MnO2 nanoparticles with dual-modality imaging and glutathione depletion enhanced HIFU-eliciting tumor immunogenic cell death

Tumor-targeted immunotherapy is a remarkable breakthrough, offering the inimitable advantage of specific tumoricidal effects with reduced immune-associated cytotoxicity. However, existing platforms suffer from low efficacy, inability to induce strong immunogenic cell death (ICD), and restrained capacity of transforming immune-deserted tumors into immune-cultivated ones. Here, an innovative platform, perfluorooctyl bromide (PFOB) nanoemulsions holding MnO₂ nanoparticles (MBP), was developed to orchestrate cancer immunotherapy, serving as a theranostic nanoagent for MRI/CT dual-modality imaging and advanced ICD. By simultaneously depleting the GSH and eliciting the ICD effect via high-intensity focused ultrasound (HIFU) therapy, the MBP nanomedicine can regulate the tumor immune microenvironment by inducing maturation of dendritic cells (DCs) and facilitating the activation of CD8⁺ and CD4⁺ T cells. The synergistic GSH depletion and HIFU ablation also amplify the inhibition of tumor growth and lung metastasis. Together, these findings inaugurate a new strategy of tumor-targeted immunotherapy, realizing a novel therapeutics paradigm with great clinical significance.

β-Cyclodextrin functionalized 3D reduced graphene oxide composite-based electrochemical sensor for the sensitive detection of dopamine

A three-dimensional reduced graphene oxide nanomaterial with β-cyclodextrin modified glassy carbon electrode (3D-rGO/β-CD/GCE) was constructed and used to detect the electrochemical behavior of dopamine (DA). The nanocomposite materials were characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), Raman spectrogram and thermogravimetric analysis (TGA), which showed that β-CD was well modified on 3D graphene with a porous structure. The electrochemical properties of different modified electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), proving the highest electron transfer rate of the 3D-rGO/β-CD modified electrode. The experimental conditions such as scan rate, pH, enrichment time and layer thickness were optimized. Under the best experimental conditions, DA was detected by differential pulse voltammetry (DPV) by 3D-rGO/β-CD/GCE with excellent electrocatalytic ability and satisfactory recognition ability, resulting in a wide linear range of 0.5-100 μM and a low detection limit (LOD) of 0.013 μM. The modified electrode based on 3D-rGO/β-CD nanocomposites is promising in the field of electrochemical sensors due to its high sensitivity and other excellent properties.

2D Co-MOF nanosheet-based nanozyme with ultrahigh peroxidase catalytic activity for detection of biomolecules in human serum samples

A two-dimensional (2D) Co-MOF nanosheet-based nanozyme was developed for colorimetric detection of disease-related biomolecules. The prepared 2D Co-MOFs exhibited ultrahigh peroxidase catalytic activity. 2D Co-MOFs can catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to the blue product oxTMB, accompanying an obvious change of absorption value at 652 nm. However, alkaline phosphatase can catalyze the hydrolysis of L-ascorbic acid-2-phosphate to produce ascorbic acid which can reduce the oxTMB to TMB, resulting in an obvious color fading. Therefore, by recording the change of absorption value at 652 nm, the 2D Co-MOF nanosheets were used to detect ascorbic acid (AA) and alkaline phosphatase (ALP). The limit of detection for AA and ALP was 0.47 μM and 0.33 U L^-1, respectively. The limit of quantification for AA and ALP was 1.56 μM and 1.1 U L^-1, respectively. The developed nanozyme was successfully used to determine alkaline phosphatase in clinical human serum samples and the results were consistent with those provided by the hospital. Furthermore, by integrating 2D Co-MOF nanosheets with image recognition and data processing function fixed on a smartphone, a portable test of ascorbic acid was reached. Schematic presentation of the preparation of two-dimensional Co-MOF nanosheet-based nanozyme and their application in portable detection of biomolecules.

Gold nanoparticles-functionalized three-dimensional flower-like manganese dioxide: A high-sensitivity thermal analysis immunochromatographic sensor

A sensitive photothermal immunochromatographic test strip (PITS) for the detection of deoxynivalenol (DON) was developed using flower-like gold nanoparticle-deposited manganese dioxide nanocarrier (FMD-G NC) labeled antibodies (Abs) as the photothermal-sensing probe. FMD was used as a template to deposit small gold nanoparticles (GNPs) to synthesize FMD-G NC with large specific surface area and significant photothermal conversion property. The FMD-G-Ab probe was competitively captured by DON target and antigen coated on test line (T-line), forming colorimetric signals under naked eyes and photothermal signals under an 808 nm laser. Under optimal conditions, the PITS exhibited sensitive and specific detection of DON from 0.19 ng mL^-1 to 12 ng mL^-1 with detection limits of 0.013 ng mL^-1, which were over 15-fold and 58-fold more sensitive than visual FMD-G-ITS and traditional GNPs-ITS. In addition, the novel FMD-G-PITS possessed a universal applicability, which could be well applied in green bean, corn, and millet.

Fluorescent polydopamine nanoparticles as a nanosensor for the sequential detection of mercury ions and l-ascorbic acid based on a coordination effect and redox reaction

Herein, a novel fluorescence nanosensor using intrinsic fluorescent polydopamine nanoparticles (PDA NPs) as an effective signal reporter has been constructed for the simple, rapid and sequential detection of mercury ions (Hg2+) and l-ascorbic acid (AA) based on a coordination effect and redox reaction. The fluorescence of the PDA NPs could be specifically quenched by Hg2+ through intense coordination effects between the Hg2+ and the groups (catechol, amine, ketone and imine) on the surface of the PDA NPs. However, when AA and Hg2+ coexisted in solution, the fluorescence of the PDA NPs pronouncedly recovered via the redox reaction of Hg2+, with it being reduced to Hg0 by AA. The fluorescence quenching mechanism of Hg2+ towards the PDA NPs and the redox reaction between Hg2+ and AA were also fully investigated. The nanosensor exhibited high sensitivity and desirable selectivity for Hg2+ and AA detection. Moreover, the strategy was successfully explored in real samples (tap water, lake water and human serum samples) with satisfactory recoveries. The developed nanosensor provides new sights and good inspiration for Hg2+ and AA detection under real conditions.

Gold-based Inorganic Nanohybrids for Nanomedicine Applications

Noble metal Au nanoparticles have attracted extensive interests in the past decades, due to their size and morphology dependent localized surface plasmon resonances. Their unique optical property, high chemical stability, good biocompatibility, and easy functionalization make them promising candidates for a variety of biomedical applications, including bioimaging, biosensing, and cancer therapy. With the intention of enhancing their optical response in the near infrared window and endowing them with additional magnetic properties, Au nanoparticles have been integrated with other functional nanomaterials that possess complementary attributes, such as copper chalcogenides and magnetic metal oxides. The as constructed hybrid nanostructures are expected to exhibit unconventional properties compared to their separate building units, due to nanoscale interactions between materials with different physicochemical properties, thus broadening the application scope and enhancing the overall performance of the hybrid nanostructures. In this review, we summarize some recent progresses in the design and synthesis of noble metal Au-based hybrid inorganic nanostructures for nanomedicine applications, and the potential and challenges for their clinical translations.

Colorimetric strategy for ascorbic acid detection based on the oxidase-like activity of silver nanoparticle single-walled carbon nanotube composites

A colorimetric assay for the determination and quantification of ascorbic acid (AA) is presented using silver nanoparticle (AgNP) single-walled carbon nanotube (AgNP/SWCNT) nanocomposites prepared using a microwave-assisted method. The AgNP/SWCNT nanocomposites possessed oxidase-like properties toward 3,3',5,5'-tetramethylbenzidine (TMB) and could catalyze the oxidation of TMB to form a blue oxidation product (λ_max = 652 nm) in the absence of H₂ O₂ . AA can specifically inhibit the oxidation of TMB, resulting in a decline of the absorbance value and blue colour fading. As such, amounts of AA can be assessed easily by the unaided eye and quantitatively using an ultraviolet-visible light spectrophotometer. Under the optimal reaction conditions, this strategy showed a good linearity ranging from 0.4 μM to 5.0 μM for AA detection, and the limit of detection was 130 nM. This assay was also applied for AA measurement in vitamin C tablets and juice samples that yielded satisfactory results.

A composite prepared from MnO2 nanosheets and a deep eutectic solvent as an oxidase mimic for the colorimetric determination of DNA

A composite was fabricated from deep eutectic solvent and MnO₂ nanosheets (DES/MnO₂) and is shown to be a viable oxidase mimic. The property, morphology and composition of DES/MnO₂ was characterized. DES/MnO₂ displays oxidase-like activity and can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to form a blue product (oxTMB) with an absorption maximum at 652 nm. Due to the presence of the DES, the polyanionic and negatively charged DNA is easily adsorbed on the surface of the composite by hydrogen bonding and electrostatic interactions. This leads to the inhibition of the oxidase-mimicking activity of DES/MnO₂. This finding was used to design a colorimetric method for the determination of DNA. The assay work in the 10-100 μg mL^-1 DNA concentration range and has a detection limit of 0.37 μg mL^-1. The inhibiting mechanism was further studied by zeta potential measurements, dynamic light scattering and transmission electron microscopy. The selectivity study shows the DES/MnO₂-TMB system to be highly selective for DNA when compared with many proteins, carbohydrates, salts and amino acid. RNA, on the other hand, interferes. The real sample analysis result illustrates that the new method can be used for the detection of DNA in bovine whole blood. Graphical abstractA novel oxidase mimic based on deep eutectic solvent-functionalized MnO₂ nanosheets was synthesized, which can directly catalyze oxidation of 3,3',5,5'-tetramethylbenzidine (TMB, colorless) to oxTMB (blue). A sensitive and convenient colorimetric strategy for visual detection of DNA was established through DES/MnO₂-TMB sensing system.