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It is difficult for drug delivery systems to release drugs as expected, often leading to undesired side effects. To solve this problem, a CuS@MSN/DOX@MnO 2 @membrane (CMDMm) was reasonably designed. It was introduced to release the drug by a double response, similar to using two keys to open two locks at the same time for one door. CuS@MSN was used as a photothermal therapy (PTT) material and carrier, and then the surface of CuS@MSN/DOX was sealed by MnO 2 to prevent drug release in advance. MnO 2 could be reduced and degraded in a tumor microenvironment. It was applied in MR imaging due to the T 1 magnetism of Mn 2+ following the reduction of MnO 2 . Finally, the 4T1 cell membrane was extracted and coated onto the surface of CuS@MSN/DOX@MnO 2 , which served as a target for 4T1 tumor cells. A noteworthy phenomenon was that the fluorescence of DOX was quenched by the coordination between DOX and CuS, and this greatly improved the interaction between DOX and CuS@MSN. However, the coordination was weakened when DOX was protonated in a tumor microenvironment (∼pH 5.0), leading to the release of DOX and fluorescence recovery. The drug release experiments showed that the release efficiency was higher at pH 5.0 with 10 mmol L -1 GSH. Through in vitro laser confocal imaging, it was successfully observed that DOX was reliably released in specific tumor cells according to the fluorescence recovery, and that there was no leakage in other cells. In short, effective double response drug release was successfully confirmed.

At present, multimodal probes for fluorescence and magnetic resonance imaging based on gadolinium-silicon hybrid nanoparticles have been reported. However, the existing preparations for these nanoparticles usually involve multi-step complicated processes and harsh conditions. Herein, to avoid complex procedures, we conveniently adopted a one-pot hydrothermal method to synthesize gadolinium (Gd)-doped silicon nanoparticles (D-Si Gd NPs) using gadolinium chloride and diethylenetriaminepentaacetic acid (DTPA) as dopants. This is the first report on the synthesis of Gd-doped silicon nanoparticles. The D-Si Gd NPs presented bright fluorescence (QY: 38%), good stability, and low biotoxicity. In particular, due to the dopants, the nanoparticles exhibited higher longitudinal relaxivity than the commercial contrast agent (Gd-DTPA) and obvious excitation-dependent photoluminescence whose emission wavelength ranged from 467 nm to 557 nm under serial excitation from 400 to 510 nm; thus, these NPs could be used for magnetic resonance imaging (MRI) and anti-counterfeiting stain applications. Moreover, the successful application of D-Si Gd NPs, such as in the T 1 -weight MRI of mice and cellular fluorescence imaging, proves that the D-Si Gd NPs have the potential to become an efficient dual-modal nanoprobe for multicolor fluorescence and magnetic resonance imaging in the future.

The development of ideal contrast agents was of great importance for multimodal imaging. However, the simple combination of different contrast components always needed long-time preparation and a tough reaction environment. In this study, we introduced a one-step microwave-assisted approach to synthesize lysozyme-capped gold nanoclusters (Lys-Au NCs) rapidly instead of traditional conditions. Irradiation with continuous microwave power shortened the reaction time from several hours to one hour and generated a large red shift (50 nm) of the fluorescence emission. The ultrasmall Lys-Au NCs showed excellent properties, including high quantum yield (19.61%), good stability, low cytotoxicity and good biocompatibility. This eco-friendly nanoprobe provided significant contrast signals in both NIRF (near-infrared fluorescence) and CT (X-ray computed tomography) in vivo imaging. Further conjugation with folic acid made the nanoprobe favorable for targeted fluorescence imaging of cancer cells and tumor-bearing mice.

In the past two decades, Cu-doped inorganic semiconductors with near-infrared (NIR) emitting have garnered stupendous research interest. Nevertheless, the incompatibility between the NIR emitting and high photoluminescence quantum yield (PLQY) of the Cu-doped fluorescent probes restricted the extensive application in biological imaging. Herein, the water soluble Cu + doped CdS quantum dots (Cu + :CdS QDs) were prepared by using a one step synthesis method in a N 2 atmosphere. The d-dots possessed an ultra small size (∼5 nm), a high QY (25.6%), NIR emission (∼700 nm) and a low cytotoxicity because of which they were used as fluorescence probes. Besides, the study of the Cu d state and the mechanism of emission proposed the explanation for the fluorescence enhancement compared with previous reports. Moreover, the optimal conditions of dopants, stabilizers, sulfur ion concentration, pH, heating time and reflux temperature were also studied systematically to acquire best-quality Cu-doped nanocrystals. Due to the excellent optical properties and favourable biocompatibility, the Cu + :CdS QDs as fluorescence probes were successfully applied to label living 3T3 cells.

Transferrin (Trf)-functionalized copper nanoclusters (Trf-Cu NCs) were fabricated as a novel red-emitting fluorescent probe for the targeted bioimaging of cancer cells. A one-pot approach was developed to prepare stable, water-soluble and red-emitting Trf-Cu NCs at room temperature via a biomineralization process with Trf as the template and ascorbic acid as a green reducing agent. Trf acted not only as a stabilizer and reducer, but also as a functional ligand for targeting the transferrin receptor. The as-prepared Trf-Cu NCs showed an intense red fluorescence with a red emission peak at 670 nm (quantum yield about 6.2%), suggesting that the probe could potentially be used for bioimaging in vivo. The developed Trf-Cu NCs had excellent photostability and water solubility and exhibited a high specificity to transferrin receptor with negligible cytotoxicity. The probe was successfully applied to the targeted bioimaging of HeLa cells.

In this study, we reported an epitope imprinting method on the surface of core-shell magnetic nanoparticles (NPs) for the recognition of target bovine serum album (BSA). The epitope was selected as the template molecule from the nonapeptide of surface-exposed C-terminus of BSA. The core-shell magnetic epitope molecularly imprinted polymers (Fe 3 O 4 @EMIPs) exhibited a specific capture activity for the corresponding target protein, BSA. The magnetic NPs made it easy to separate the imprinted material from solution by an external magnetic field, and the thin imprinted layer presented fast kinetics for the rebinding of the target protein. Moreover, the Fe 3 O 4 @EMIPs could separate BSA from the bovine blood sample. The epitope imprinting approach combined with magnetic NPs provided an easy and fast method for the specific recognition of BSA.

Magnetic quantum dots (MQDs) are an important class of agents for fluorescence (FL)/magnetic resonance (MR) dual-modal imaging due to their excellent optical and magnetic properties. However, functional MQDs prepared by a simple room-temperature route as FL/MR dual-modal imaging probes are lacking. Herein, we report the fabrication of Gd-doped CdTe quantum dots (Gd:CdTe QDs) as an agent for FL/MR dual-modality imaging. The as-designed QDs with an ultrasmall particle size are synthesized by a facile one-pot aqueous synthesis approach at room temperature. They emit strong fluorescence at 640 nm with a quantum yield of 37% in water, and they have a high longitudinal relaxation rate (r 1 ) value of 3.27 mM -1 s -1 . With the further conjugation of folic acid, the Gd:CdTe QDs can successfully label live HepG2 cells for targeted cellular imaging and present no evidence of cellular toxicity up to the concentration of 0.5 mg mL -1 . They have been employed as a suitable contrast agent successfully for tumor-targeted FL/MR dual-modal imaging in a mouse model.

A facile and efficient approach for preparation of ionic liquid functionalized silica-capped CdTe QDs (CdTe/SiO 2 /IL) was proposed in this work. The imidazolium-based ionic liquid N-3-(3-trimethoxysilylpropyl)-3-methyl imidazolium chloride was introduced and anchored on the surface of silica-capped CdTe QDs by the sol-gel technique, which played the role of a recognition element due to the covalent coordination binding between the heme group of hemoprotein and the imidazolium cation in the ionic liquid. The synthetic CdTe/SiO 2 /IL was further characterized by elemental analysis, transmission electronic microscopy (TEM), X-ray photoelectron spectra (XPS) and Fourier transform infrared spectroscopy (FT-IR). Combining the merits of the fluorescence property of the QDs and the covalent interaction of the ionic liquid with hemoproteins, the CdTe/SiO 2 /IL exhibited high adsorption capacity and good specificity toward hemoproteins and also was successfully applied in the fluorescence detection of hemoprotein in biological fluid. The strategy provided a promising way to fabricate functionalized fluorescence materials as biomedical/chemical sensors for the separation and detection of hemoproteins in proteomics research.

In this work, aminophenylboronic acid functionalized mesoporous silica coated CdTe quantum dots (APBA-coated QDs) were synthesized and applied to the selective capture and fluorescent quantification of glycoproteins. The as-prepared APBA-coated QDs, relying on the interaction between APBA and cis-diol containing structures, demonstrated excellent selectivity for the glycoproteins. Their high surface area and APBA-enriched silica matrixes give rise to faster binding kinetics and higher binding capacity for the glycoproteins, which further make them attractive for biomedical/chemical sensing applications. Based on the fluorescent properties of the particles, the as-prepared APBA-coated QDs were successfully applied to the fluorescence quantification of glycoproteins. The present study provides a facile strategy to fabricate functionalized fluorescent materials and is of great significance for isolation and detection of glycoproteins in proteomics.