Ag-HPBs by a coating-etching strategy and their derived injectable implants for enhanced tumor photothermal treatment

Target-driven functionalized DNA hydrogel capillary sensor for SARS-CoV-2 dual-mode detection

Coronavirus disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused secondary pandemic, which still poses a serious threat to physical health and economic development. Herein, the target-driven functionalized DNA hydrogel capillary sensor based on cascade signal amplification and carbon coated cobalt manganese modified by prussian blue and platinum nanoparticles (MnCo@C-Pt-PB NPs) has been successfully developed for dual-mode detection of SARS-CoV-2. The cascade signal amplification triggered by target RNA causes the permeability of the DNA hydrogel loaded in the capillary to be destroyed, thereby releasing the embedded MnCo@C-Pt-PB NPs as signal molecules into 3,3',5,5'-tetramethylbenzidine/hydrogen peroxide (TMB/H2O2) solution under the driving of capillarity. The colorless TMB is then catalyzed to blue oxidation products (oxTMB) due to peroxidase-like activity of MnCo@C-Pt-PB NPs, and MnCo@C-Pt-PB NPs and oxTMB with photothermal properties synergistically increase the system temperature under near-infrared irradiation, which are recorded by portable devices to achieve dual-mode detection. Signals intensity are proportional to the logarithm of T-RNA concentration in a wide detection range (100 aM-100 pM), with a detection limit of 100 aM. Moreover, the reliability of the developed method in oropharyngeal swabs samples has also been validated. The signal conversion and amplification function of functionalized DNA hydrogel enhances the convenience, sensitivity and versatility of the developed method, which is promising to be applied in environmental safety, molecular diagnostic assays and disease prevention.

Hollow Prussian blue with ultrafine silver nanoparticle agents (Ag-HPB) integrated sensitive and flexible biosensing platform with highly enzyme loading capability

Herein, the hollow Prussian blue with ultra-small silver nanoparticle agents (Ag-HPB) was prepared by the coating-etching method by applying Prussian blue (PB) coating on Ag nanoparticles (Ag NPs) and diffusing Ag NPs into the PB framework. The flexible biosensing platform based on Ag-HPB nanocomposites incorporated the excellent electrical conductivity of Ag NPs and the superior enzyme loading capacity of the hollow structure, which significantly enhanced its sensing performance. Subsequently, take glucose oxidase (GOx) and acetylcholinesterase (AChE) as examples. The sensing platform displayed a good sensitive response to glucose (Glu) (24.37 μA mM-1 cm-2) and a considerable limit of detection (LOD) for trichlorfon (TCF) as 2.28 pg/mL while exhibiting high stability and good reproducibility. Moreover, it can be applied to monitor trichlorfon in apple samples. Promisingly, the Ag-HPB prepared by the coating-etching strategy provides a reliable strategy for further development of sensitive and flexible biosensing platforms with excellent electrical conductivity and high enzyme loading.

Hybrid Au-star@Prussian blue for high-performance towards bimodal imaging and photothermal treatment

In recent years, branched or star-shaped Au nanostructures composed of core and protruding arms have attracted much attention due to their unique optical properties and morphology. As the clinically adapted nanoagent, prussian blue (PB) has recently gained widespread attention in cancer theranostics with potential applications in magnetic resonance (MR) imaging. In this article, we propose a hybrid star gold nanostructure（Au-star@PB）as a novel theranostic agent for T1-weighted magnetic resonance imaging (MRI)/ photoacoustic imaging（PAI） and photothermal therapy (PTT) of tumors. Importantly, the Au-star@PB nanoparticles function as effective MRI/PA contrast agents in vivo by increasing T1-weighted MR/PAI signal intensity and as effective PTT agents in vivo by decreasing the tumor volume in MCF-7 tumor bearing BALB / c mouse model as well as in vitro by lessening tumor cells growth rate. Interestingly, we found the main photothermal effect of Au-star@PB is derived from Au-star, but not PB. In summary, the hybrid structure of Au-star@PB NPs with good biological safety, significant photostability, dual imaging capability, and high therapeutic efficiency, might offer a novel avenue for the future diagnosis and treatment of cancer.

Iron-Based Hollow Nanoplatforms for Cancer Imaging and Theranostics

Over the past decade, iron (Fe)-based hollow nanoplatforms (Fe-HNPs) have attracted increasing attention for cancer theranostics, due to their high safety and superior diagnostic/therapeutic features. Specifically, Fe-involved components can serve as magnetic resonance imaging (MRI) contrast agents (CAs) and Fenton-like/photothermal/magnetic hyperthermia (MTH) therapy agents, while the cavities are able to load various small molecules (e.g., fluorescent dyes, chemotherapeutic drugs, photosensitizers, etc.) to allow multifunctional all-in-one theranostics. In this review, the recent advances of Fe-HNPs for cancer imaging and treatment are summarized. Firstly, the use of Fe-HNPs in single T1-weighted MRI and T2-weighted MRI, T1-/T2-weighted dual-modal MRI as well as other dual-modal imaging modalities are presented. Secondly, diverse Fe-HNPs, including hollow iron oxide (IO) nanoparticles (NPs), hollow matrix-supported IO NPs, hollow Fe-complex NPs and hollow Prussian blue (PB) NPs are described for MRI-guided therapies. Lastly, the potential clinical obstacles and implications for future research of these hollow Fe-based nanotheranostics are discussed.

Exogenous Contrast Agents in Photoacoustic Imaging: An In Vivo Review for Tumor Imaging

The field of cancer theranostics has grown rapidly in the past decade and innovative 'biosmart' theranostic materials are being synthesized and studied to combat the fast growth of cancer metastases. While current state-of-the-art oncology imaging techniques have decreased mortality rates, patients still face a diminished quality of life due to treatment. Therefore, improved diagnostics are needed to define in vivo tumor growths on a molecular level to achieve image-guided therapies and tailored dosage needs. This review summarizes in vivo studies that utilize contrast agents within the field of photoacoustic imaging-a relatively new imaging modality-for tumor detection, with a special focus on imaging and transducer parameters. This paper also details the different types of contrast agents used in this novel diagnostic field, i.e., organic-based, metal/inorganic-based, and dye-based contrast agents. We conclude this review by discussing the challenges and future direction of photoacoustic imaging.

Self-assembled CeVO4/Ag nanohybrid as photoconversion agents with enhanced solar-driven photocatalysis and NIR-responsive photothermal/photodynamic synergistic therapy performance

The plasmonic cerium vanadate (CeVO₄) semiconductor and plasmonic silver (Ag) metal exhibit a localized surface plasmon resonance (LSPR) effect in the visible (Vis)-light region; however, weak absorption in the near-infrared (NIR) region restricts their environmental remediation and biomedical application. Herein, CeVO₄/Ag nanohybrids with self-assembled heterostructure and improved Vis/NIR light absorption were synthesized from CeVO₄ nanosheets and AgNO₃ solution, which could serve as potential solar-driven catalytic agents and near-infrared (NIR) light responsive anticancer agents. Oleic acid-stabilized CeVO₄ nanosheets were modified with the HS-PEG₁₀₀₀-OH by the thiol-ene click reaction and presented self-assembly morphology in aqueous solution due to hydrophobic-hydrophobic interactions. Sulfhydryl (-SH) groups provided stable sites for Ag⁺ ions on the surface of CeVO₄, and Ag⁺ ions could be directly reduced by Ce³⁺ ions to form CeVO₄/Ag heterojunction nanocrystals (NCs). Due to the higher absorption in the Vis/NIR light region than CeVO₄ nanosheets, CeVO₄/Ag NCs led to the improved solar light responsive photocatalytic degradation of organic dyes. Upon the exposure of these NCs to an 808 nm laser, CeVO₄/Ag NCs show high photothermal conversion efficiency, ROS generation ability and photoacoustic (PA) signal for implementing PA imaging-guided photothermal/photodynamic synergistic cancer therapy with better tumor inhibition effect.

Fluorescent and photoacoustic bifunctional probe for the detection of ascorbic acid in biological fluids, living cells and in vivo

Photoacoustic imaging (PAI) has emerged as a promising clinical technology, thanks to its high-resolution in deep tissues. However, the lack of specificity towards analytes limits further application of the PA probe in molecular imaging. To this end, we herein report a PA and fluorescence (FL) dual-modal probe for the selective detection of ascorbic acid (AA). To realize this design, cobalt oxyhydroxide (CoOOH) was adopted as a multifunctional platform (PA contrast agent, FL quencher and specific oxidant to AA) and hybridized with red-emissive carbon dots (RCDs). In the presence of AA, CoOOH is reduced to Co2+ and meanwhile releases RCDs, resulting in the decrease of PA and recovery of FL signals. We demonstrated the AA detection capabilities of the probe in complicated biological fluids (human serum and urine), living cells, and dual-modal FL/PA imaging in vivo. This work revealed the PAI capacity of CoOOH for the first time, which may inspire researchers to design other CoOOH-based PA probes and further employ RCDs in biology and the clinic.