We are interested in fabrication and characterization of low-dimensional nanostructured materials with specific functionality and their applications in energy, medicine, and quantum sensing
Correlated translation and rotation tracking of single particles can provide important information for understanding the dynamics of live systems and their interaction with the probes in nanoscale. Here we develop synchronized 3D translation and 3D rotation tracking of single diamond nanoparticles based on nitrogen-vacancy center quantum sensing. We first tracked the 6D motion of diamond particles attached to a spherical giant plasma membrane vesicle (GPMV). With full 6D information, we are able to eliminate the geometric effect associated with the translation on a curved surface and reveal the net rotation of the diamond particle with respect to the GPMV. We then apply the 6D tracking technique to the study of live cell dynamics. We measure motion characteristics of nanodiamonds (NDs) on cell membranes at different physiological conditions. The results suggest that the motion of the NDs on the plasma membranes is associated with cell metabolic activities.
Spatially resolved measurement of material deformation is critical to evaluate mechanical properties of materials in general, and key to understanding fundamental mechano-stimuli induced response of live systems. Existing techniques may access localized properties of materials at nanoscale, but miss key information of deformation at locations away from the force-loading positions. By combining the high-sensitivity of spin sensing technique based on nitrogen-vacancy (NV) centres in nanodiamond and the high spatial resolution of AFM indentation, we demonstrate a method in which the deformation of materials can be non-locally measured with a high precision down to 5 nm, representing a one-to-two order of magnitude improvement to the existing techniques. By reconstructing material surface deformation upon an AFM indentation using the rotation data of nanodiamonds, we mapped out the deformation of PDMS thin films in air and that of gelatin microgel particles in water. The deformed surface profiles were obtained with sufficiently high precision to disclose the heterostructures in the PDMS film (due to surface oxidation), and to measure the elastocapillary effect at the gelatin/water interface.
To exploit the advantages of diamond quantum sensing for studying the broad range of parameters relevant to cellular machinery, a possible approach is to introduce a transducer to convert variations of such parameters to magnetic signals that can be sensitively picked up by diamond NV in its proximity, and the availability of various stimuli-responsive hydrogels enables the implementation of such a plan. A ND@hydrogel-MNP hybrid structured nanoparticle is designed for such a purpose. The volume phase transition of the hydrogel shell and hence the sharp distance variation between the ND and the MNPs induces a large change of the magnetic field that can be sensed by the NV centers via optically detected magnetic resonance (ODMR), a well-established optical method for magnetometry measurement. As the hydrogel can be chemically engineered to be responsive to various stimuli (glucose, pH, enzyme, etc.), the hybrid scheme can be extended to the detection of a broad range of biochemical parameters.
Capacity increase with cycling has been observed in a number of metal oxide based anode materials for Li-ion batteries, but its origin was largely under debate. By employing ex situ X-ray based methods, we identify that reversible formation/decomposition of lithium oxide, pulverization of Fe3O4 nanoparticles, and electrolyte reactions, are contributors to the enhanced capacity observed in the Fe3O4 electrode upon long cycling. Introducing three-dimensional graphene foam to form a composite with Fe3O4 nanoparticles largely increases the capacity (~ 1220 mA h g-1 vs. ~ 690 mA h g-1) and promotes the cycling induced capacity enhancement (an earlier capacity rise and a faster rising rate) of the Fe3O4 electrode. Together with Fe3O4 nanoparticles, the presence of graphene effectively promotes the electrolyte reactions and reversible formation/decomposition of lithium oxide. At the same time, activation of GF also occurs in the presence of Fe3O4 nanoparticles, further increases the capacity of the nanocomposite.
An ideal nanoparticle (NP) carrier-drug system requires effective cellular uptake, controllable release, and safe excretion from the biological system after functioning. We have designed SiO2 based self-decomposable nanoparticles as effective drug carriers for cancer therapeutics. A co-growth mechanism of drug and the carrier materials allows the inside out diffusion of drug molecules (drug release), leading to the self-decomposition of the nanoparticles simultaneously. This enables effective drug release from the carrier as well as easy renal clearance of the carrier materials after drug release.
We show that by employing different loading schemes of the drugs, one can manipulate the drug release profiles in many different ways.
Sustained release of the drug at cellular level serves as effect strategy to bypass the multidrug resistance effect in cancer cells, and programmable multidrug release leads to significantly enhanced drug efficacy.
By surface decorating the nanocarriers with Au nanoparticles, we discovered a correlation between the drug release from the carrier and the morphological evolution of AuNPs, which also left the carrier and changed their aggregation states along with the drug release process. This finding enabled the real time monitoring of the drug release at local sites (e.g. tumor) in a quantitative manner by recording the CT signal evolution of the AuNPs.
