Graphene Quantum Dots Functionalized with 4-Amino-2, 2, 6, 6-Tetramethylpiperidine-N-Oxide as Fluorescence “Turn-ON” Nanosensors

Molybdenum Trioxide Quantum Dot-Encapsulated Nanogels for Virus Detection by Surface-Enhanced Raman Scattering on a 2D Substrate

The use of nanogels (NGs) to modulate surface-enhanced Raman scattering (SERS) activities is introduced as an innovative strategy to address certain critical issues with SERS-based immunoassays. This includes the chemical deformation of SERS nanotags, as well as their nonspecific interactions and effective "hotspots" formation. Herein, the polymeric cocoon and stimuli-responsive properties of NGs were used to encapsulate SERS nanotags containing plasmonic molybdenum trioxide quantum dots (MoO₃-QDs). The pH-controlled release of the encapsulated nanotags and their subsequent localization by maleimide-functionalized magnetic nanoparticles facilitated the creation of "hotspots" regions with catalyzed SERS activities. This approach resulted in developing a biosensing platform for the ultrasensitive immunoassays of hepatitis E virus (HEV) or norovirus (NoV). The immunoassays were optimized using the corresponding virus-like particles to attain limits of detection of 6.5 and 8.2 fg/mL for HEV-LPs and NoV-LPs, respectively. The SERS-based technique achieved a signal enhancement factor of up to ∼10⁸ due to the combined electromagnetic and chemical mechanisms of the employed dual-SERS substrate of MoO₃-QDs/2D hexagonal boron nitride nanosheets. The highlight and validation of the developed SERS-based immunoassays was the detection of NoV in infected patients' fecal specimen and clinical HEV G7 subtype. Importantly, this system can be used to maintain the stability of SERS nanotags and improve their reliability in immunoassays.

Graphene quantum dots prepared from dried lemon leaves and microcrystalline mosaic structure

There are the smallest structural units (carbon and/or quantum dots) in the structure of living plants. This carbon and/or quantum dots are stem cells of plants.

A prevascularized nerve conduit based on a stem cell sheet effectively promotes the repair of transected spinal cord injury

Spinal cord injury (SCI) can result in severe loss of motor and sensory function caused by ischemia and hypoxia, which are the key limiting factors of SCI rehabilitation. Vascularization is considered an effective way to resolve the issues of ischemia and hypoxia. In this regard, we first fabricated prevascularized nerve conduits (PNC) based on the prevascularized stem cell sheet and evaluated their repair effects by implanting them into transected SCI rats. A better healing effect was presented in the PNC group than in the control group and the nonprevascularized nerve conduit (NPNC) group as shown in H&E staining and the Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale assessment. In addition, the expression of β-III tubulin (Tuj-1) in the PNC group was higher than that in the control group and the NPNC group because of the introduction of MSCs. Conversely, the expression of the glial fibrillary acidic protein (GFAP) in both experimental groups was lower than that in the control group because of the inhibitory effect of MSCs on glial scar formation. Taken together, the introduction of prevascularization into the neuron conduit was an effective solution for improving the condition of ischemia and hypoxia, inhibiting glial scar formation, and promoting the healing of SCI, which implied that the PNC may be a potential alternative material to biomaterials for SCI rehabilitation. STATEMENT OF SIGNIFICANCE: 1. Prevascularized stem cell sheet was first used to repair spinal cord injury (SCI). 2. Prevascularized stem cell sheet use can effectively resolve the challenges faced during SCI, including ischemia and hypoxia and the limited regenerative ability of the remained neurons. 3. Prevascularized stem cell sheet was found to accelerate the healing of SCI as compared to those in the control group and the pure stem cell sheet group. 4. The introduction of stem cells can effectively inhibit the formation of a glial scar.

Nitroxide-radicals-modified gold nanorods for in vivo CT/MRI-guided photothermal cancer therapy

Purpose

This article presents a report of the synthesis, characterization, and biomedical application of nitroxide-radicals-modified gold nanorods (Au-TEMPO NRs) for imaging-guided photothermal cancer therapy.

Patients and methods

Au nanorods were synthesized through seed-mediated growth method, 4-Amino-TEMPO was added and the reaction proceeded under magnetic stirring.

Results

With a mean length of 39.2 nm and an average aspect ratio of approximately 3.85, Au-TEMPO NRs showed good photothermal ability when they were irradiated by 808-nm laser. Au-TEMPO NRs could be stored in PBS for more than 1 month, showed no cytotoxicity against both tumor and normal cells at a concentration of up to 3 mg/mL, and functioned as a dual-mode contrast agent for CT/magnetic resonance (MR) imaging in vitro and in vivo, due to their high X-ray attenuation of Au and good r1 relaxivity of nitroxide radicals. Further, they had a long retention time (~4 hours) in the main organs, which enabled a long CT/MR imaging time window for diagnosis. Bio-distribution results revealed that these Au-TEMPO NRs passively aggregated in the liver and spleen. After irradiation by 808-nm laser, Au-TEMPO NRs could ablate the solid tumor in 4T1 tumor-bearing mice, which implied they were a potential theranostic agent for dual-mode imaging and photothermal cancer therapy.

Conclusion

This type of Au-TEMPO NRs with the abilities of CT/MR imaging and photothermal therapy, can play an active role in imaging-guided photothermal cancer therapy.