We report a new class of turn-on surface enhanced Raman scattering (SERS) sensors for the sensitive and selective detection of cadmium ion (Cd2+) by taking advantage of the interparticle plasmonic ...coupling generated in the process of Cd2+-selective nanoparticle self-aggregation. The SERS-active nanoparticles consist of 41-nm gold nanoparticles, encoded with a Raman-active dye through a disulfide anchoring group, and a layer of Cd2+-chelating polymer brush coating grafted on the nanoparticle via surface-initiated atom transfer radical polymerization. These SERS nanoparticles are optimized to remain spectrally silent when staying as single particles. Addition of Cd2+ leads to interparticle self-aggregation and immediately turns on the SERS fingerprint signal with up to 90-fold of signal enhancement. The selectivity of the SERS nanoparticle for Cd2+ was also examined, showing that various common metal ions cannot induce interparticle self-aggregation and the turn-on of SERS signal. In contrast to nanoparticle-based colorimetric assays, the SERS probe is also capable of detecting Cd2+ in heavily colored samples.
Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable ...excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double‐layered plasmonic–magnetic vesicle assembled from Janus amphiphilic Au‐Fe3O4 NPs grafted with polymer brushes of different hydrophilicity on Au and Fe3O4 surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au‐Fe3O4 NPs in opposite direction, and the orientation of Au or Fe3O4 in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers.
Double‐layered plasmonic–magnetic vesicles were prepared by self‐assembly of Janus Au‐Fe3O4 nanoparticles. The nanoparticles were grafted with amphiphilic polymer brushes of different hydrophilicity on Au and Fe3O4 surfaces separately.
Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient ...response rates and dose‐limiting toxicity remain as major dilemmas for immunotherapy. Stimuli‐responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti‐tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti‐tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long‐term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.
Stimuli‐responsive nanoparticles activated by endo/exo‐microenvironments, including acidity, high‐level glutathione, overexpressed enzymes, and reactive oxygen species, various external stimuli, and so forth, are developed to deliver immunoregulatory agents controllably to eventually amplify the synergistic immunotherapy efficacy of primary or metastatic malignant tumors and acquire a long‐term immune memory to prevent tumor recurrence.
Clustering of magnetic nanoparticles (MNPs) is perhaps the most effective, yet intriguing strategy to enhance T2 relaxivity in magnetic resonance imaging (MRI). However, the underlying mechanism is ...still not fully understood and the attempts to generalize the classic outersphere theory from single particles to clusters have been found to be inadequate. Here we show that clustering of MNPs enhances local field inhomogeneity due to reduced field symmetry, which can be further elevated by artificially involving iron oxide NPs with heterogeneous geometries in terms of size and shape. The r2 values of iron oxide clusters and Landau-Lifshitz-Gilbert simulations confirmed our hypothesis, indicating that solving magnetic field inhomogeneity may become a powerful way to build correlation between magnetization and T2 relaxivity of MNPs, especially magnetic clusters. This study provides a simple yet distinct mechanism to interpret T2 relaxivity of MNPs, which is crucial to the design of high-performance MRI contrast agents.
We report the development of a highly efficient photocatalytic system by immobilizing high-quality CdS quantum dots and dendritic Pt nanocrystals on thiol-functionalized graphene substrates. We have ...demonstrated that the use of QDs with compact sizes leads to a dramatically enhanced performance in comparison with their bulk counterparts. Our design allows for systematic examination of the impact of QD sizes and the loading, morphology, and surface coating of the Pt nanocrystal cocatalyst on the H2 evolution activity. It was found that the CdS-Pt binary system has a high photocatalytic efficiency of 1.37 mmol h(-1) for visible light driven H2 evolution, and there was a 30% improvement by introducing the thiolated reduced graphene oxide to form the three-component CdS-Pt-Gcys nanocomposites. The highest H2 evolution rate of 2.15 mmol h(-1) (λ ≥ 420 nm) with a QE of 50.7% was achieved by further photo-annealing of the CdS-Pt-Gcys nanocomposites prior to the photocatalytic reaction.
Multimodal imaging in the second near-infrared window (NIR-II) guided cancer therapy is a highly precise and efficient cancer theranostic strategy. However, it is still a challenge to develop ...activated NIR-II optical imaging and therapy agents. In this study, we develop a pH-responsive hybrid plasmonic-fluorescent vesicle by self-assembly of amphiphilic plasmonic nanogapped gold nanorod (AuNNR) and fluorescent down-conversion nanoparticles (DCNP) (AuNNR-DCNP Ve), showing remarkable and activated NIR-II fluorescence (FL)/NIR-II photoacoustic (PA) imaging performances. The hybrid vesicle also exhibited superior loading capacity of doxorubicin as a superior drug carrier and efficient radiosensitizer for X-ray-induced radiotherapy. Interestingly, the accumulated hybrid AuNNR-DCNP Ve in the tumor resulted in a recovery of NIR-II FL imaging signal and a variation in NIR-II PA imaging signal. Dual activated NIR-II PA and FL imaging of the hybrid vesicle could trace drug release and precisely guided cancer radiotherapy to ultimately reduce the side effects to healthy tissue.
Gold nanoparticles (AuNPs) are a popular material in the field of nanoscience because of their excellent biocompatibility and unique physical and chemical properties, and have been widely used in the ...biomedical field. AuNPs have a simple preparation method, controllable shape and size, high electron density and atomic number, superparamagnetic properties, and radiation sensitization effect, and their optical absorbance can be adjusted to the required biological window; thus, AuNPs are suitable for cancer imaging (photoacoustic imaging, computed tomography, and magnetic resonance imaging), photothermal therapy, and radiotherapy. AuNPs can also be used as carriers to load photosensitizers or chemotherapeutic agents, and therefore, can also be used in photodynamic therapy and chemotherapy. In summary, AuNPs and their assemblies can simultaneously realize cancer diagnosis and treatment, providing a new idea in the development of precision medical treatment.
The review has summarized the biomedical applications of plasmonic gold nanoagents in cancer diagnosis, including NIR‐I PA imaging, NIR‐II PA imaging, ratiometric PA imaging, CT imaging, MRI and multi‐modal imaging; and in cancer therapies including PTT, PDT, radiotherapy, chemotherapy, and combined therapy.
Various beneficial properties of graphitic carbon nitride (g‐CN) have been discovered during the promotion of its visible‐light‐driven photocatalytic activity for water splitting. These properties ...enable g‐CN working as a sensing signal transducer with multiple output modes. In this review, state‐of‐the‐art sensing applications of tailored g‐CN nanostructures in the recent years are presented. Initially, g‐CN nanoarchitectures featuring large surface areas, abundance of active sites, and high dispersity in water are presented along with their preparation methods. Then, sensing applications of these g‐CN nanoarchitectures are described in sequence of the immobilization of recognition elements; semiconductor and electron donating properties derive signaling transduction modes, and efficient approaches for improving sensing performances. The review is concluded with a summary and some perspectives on the challenges and future possibilities of this research field.
The fabrication, sensing application, and future perspectives of a graphitic carbon nitride (g‐CN)‐based sensor are highlighted, which includes the following: the design and synthesis of g‐CN nanoarchitectures that are suitable for sensor construction; the strategy of conjugation of recognition elements to g‐CN nanoarchitectures, signaling transduction modes derived from g‐CN's semiconductor and electron donating properties; and efficient approaches for improving sensing performances, i.e., with high sensitivity, specificity, and reproducibility.
Ti
3
C
2
T
x
MXene/Cu
x
O composites were prepared by acid etching combined with electrochemical technique. The abundant active sites on the surface of MXene greatly increase the loading of Cu
x
O ...nanoparticles, and the synergistic effect between the different components of the composite can accelerate the oxidation reaction of glucose. The results indicate that at the working potential of 0.55 V (vs. Ag/AgCl), the glucose sensor based on Ti
3
C
2
T
x
MXene/Cu
x
O composite presents large linear concentration ranges from 1 µM to 4.655 mM (sensitivity of 361 µA mM
−1
cm
−2
) and from 5.155 mM to 16.155 mM (sensitivity of 133 µA mM
−1
cm
−2
). The limit of detection is 0.065 µM. In addition, the sensor effectively avoids the oxidative interference of common interfering species such as ascorbic acid, dopamine and uric acid. The sensor has good reproducibility, stability and acceptable recoveries for the detection of glucose in human sweat sample (97.5-103.3%) with RSD values less than 4%. Based on these excellent properties it has great potential for the detection of glucose in real samples.
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