The recently emerged exceedingly small magnetic iron oxide nanoparticles (ES-MIONs) (<5 nm) are promising T-weighted contrast agents for magnetic resonance imaging (MRI) due to their good biocompatibility compared with Gd-chelates. However, the best particle size of ES-MIONs for T imaging is still unknown because the synthesis of ES-MIONs with precise size control to clarify the relationship between the r (or r/r) and the particle size remains a challenge. In this study, we synthesized ES-MIONs with seven different sizes below 5 nm and found that 3.6 nm is the best particle size for ES-MIONs to be utilized as T-weighted MR contrast agent. To enhance tumor targetability of theranostic nanoparticles and reduce the nonspecific uptake of nanoparticles by normal healthy cells, we constructed a drug delivery system based on the 3.6 nm ES-MIONs for T-weighted tumor imaging and chemotherapy. The laser scanning confocal microscopy (LSCM) and flow cytometry analysis results demonstrate that our strategy of precise targeting via exposure or hiding of the targeting ligand RGD on demand is feasible. The MR imaging and chemotherapy results on the cancer cells and tumor-bearing mice reinforce that our DOX@ES-MION3@RGD@mPEG3 nanoparticles are promising for high-resolution T-weighted MR imaging and precise chemotherapy of tumors.

The detection of circulating tumor cells (CTCs) in the blood of cancer patients is crucial for early cancer diagnosis, cancer prognosis, evaluation of the treatment effect of chemotherapy drugs, and choice of cancer treatment options. In this study, we propose new surface-enhanced Raman scattering (SERS) nanoparticles for the direct detection of CTCs in the blood. Under the optimized experimental conditions, our SERS nanoparticles exhibit satisfying performances for the direct detection of cancer cells in the rabbit blood. A good linear relationship is obtained between the SERS intensity and the concentration of cancer cells in the range of 5-500 cells/mL (R(2) = 0.9935), which demonstrates that the SERS nanoparticles can be used for the quantitative analysis of cancer cells in the blood and the limit of detection is 5 cells/mL, which is lowest compared with the reported values. The SERS nanoparticles also have an excellent specificity for the detection of cancer cells in the rabbit blood. The above results reinforce that our SERS nanoparticles can be used for the direct detection of CTCs in the blood with excellent specificity and high sensitivity.

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Magnetic resonance imaging (MRI), a sophisticated promising three-dimensional tomographic noninvasive diagnostic technique, has intrinsic advantage in safety compared with radiotracer and optical imaging modalities. However, MRI contrast agents are less sensitive than complexes used in other imaging techniques. Usually clinical used Gd-based complexes MRI-T 1 contrast agents are toxic. Therefore, demand for nontoxic novel T 1 -weighted MRI potential candidate with ultrasensitive imaging and advanced functionality is very high. In this research, silica coated ultra small monodispersed super-paramagnetic iron oxide nanoparticles were synthesized via thermal decomposition method which demonstrated high performance T 1 -weighted MRI contrast agent for heart, liver, kidney and bladder based on in vivo imaging analyses.Transmission electron microscopy (TEM) results have illustrated that the diameter of SPIONPs was in the range of 4nm and the average size of Fe 3 O 4 @SiO 2 was about 30~40nm. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed the purity in phase of the prepared SPIONPs. These magnetite nanoparticles exhibited weak magnetic moment at room temperature because of spin-canting effect which escorted high positive signal enhancement ability. MTT assays and histological analysis demonstrated good biocompatibility of the SPIONPs in vitro and in vivo. In addition, the silica coated ultra small (4nm-sized) magnetite nanoparticles exhibited a good r 1 relaxivity of 1.2mM -1 s -1 and low r 2 /r 1 ratio of 6.5 mM -1 s -1 . In vivo T 1 -weighted MR imaging of heart, liver, kidney and bladder in mice after intravenous injection of nanoparticles further verified the high sensitivity and biocompatibility of as-synthesized magnetite nanoparticles. These results reveal silica coated SPIONPs as a promising candidate for T 1 contrast agent with extraordinary capability to enhance MR images.

Bacterial infections in wounds often delay the healing process, and may seriously threaten human life. It is urgent to develop wound dressings to effectively detect and treat bacterial infections. Nanoparticles have been extensively used in wound dressings because of their specific properties. This review highlights the recent progress on nanoparticle-based wound dressings for bacterial detection and therapy. Specifically, nanoparticles have been applied as intrinsic antibacterial agents or drug delivery vehicles to treat bacteria in wounds. Moreover, nanoparticles with photothermal or photodynamic property have also been explored to endow wound dressings with significant optical properties to further enhance their bactericidal effect. More interestingly, nanoparticle-based smart dressings have been recently explored for bacteria detection and treatment, which enables an accurate assessment of bacterial infection and a more precise control of on-demand therapy.

Exploring novel surface-enhanced Raman scattering (SERS) active materials with high detection sensitivity, excellent biocompatibility, low biotoxicity, and good spectral stability is urgently required for efficacious cancer cell diagnosis. Herein, black TiO2 nanoparticles (B-TiO2 NPs) with crystal–amorphous core–shell structure are successfully developed. Remarkable SERS activity is derived from the synergistic effect of the promising crystal–amorphous core–shell structure. Abundant excitons can be generated by high-efficiency exciton transitions in the crystal core, a feature that provides sufficient charge source. Significantly, the novel crystal–amorphous heterojunction enables the efficient exciton separation at the crystal–amorphous interface, which can effectively facilitate charge transfer from the crystal core to the amorphous shell and results in exciton enrichment at the amorphous shell. Kelvin probe force microscopy (KPFM) confirms the Fermi level of the amorphous layer shifting to a relatively low position compared to that of the crystal core, allowing efficient photoinduced charge transfer (PICT) between the amorphous shell and probe molecules. The first-principles density functional theory (DFT) calculations further indicate that the amorphous shell structure possesses a narrow band gap and a relatively high electronic density of state (DOS), which can effectively promote vibration coupling with target molecules. Moreover, MCF-7 drug-resistant (MCF-7/ADR) breast cancer cells can be quickly and accurately diagnosed based on the high-sensitivity B-TiO2-based SERS bioprobe. To the best of our knowledge, this is the first time the crystal–amorphous core–shell heterojunction enhancement of the TiO2-molecule PICT process, which widens the application of semiconductor-based SERS platforms in precision diagnosis and treatment of cancer, has been investigated.

The existence of cancer stem cells (CSCs) poses a major obstacle for the success of current cancer therapies, especially the fact that non-CSCs can spontaneously turn into CSCs, which lead to the failure of the treatment and tumor relapse. Therefore, it is very important to develop effective strategies for the eradication of the CSCs. In this work, we have developed a CSCs-specific targeted, retinoic acid (RA)-loaded gold nanostars-dendritic polyglycerol (GNSs-dPG) nanoplatform for the efficient eradication of CSCs. The nanocomposites possess good biocompatibility and exhibit effective CSCs-specific multivalent targeted capability due to hyaluronic acid (HA) decorated on the multiple attachment sites of the bioinert dendritic polyglycerol (dPG). With the help of CSCs differentiation induced by RA, the self-renewal of breast CSCs and tumor growth were suppressed by the high therapeutic efficacy of photothermal therapy (PTT) in a synergistic inhibitory manner. Moreover, the stemness gene expression and CSC-driven tumorsphere formation were significantly diminished. In addition, the in vivo tumor growth and CSCs were also effectively eliminated, which indicated superior anticancer activity, effective CSCs suppression, and prevention of relapse. Taken together, we developed a CSCs-specific targeted, RA-loaded GNSs-dPG nanoplatform for the targeted eradication of CSCs and for preventing the relapse.