Huihui Wang

A non-invasive NMR and MRI method to analyze the rehydration of dried sea cucumber

Sea cucumbers possess high-value and bioactive components that have been used for human food and pharmaceuticals in treating a wide number of ailments. Most of the sea cucumber products on the market are dehydrated due to the immediate autolysis that occurs upon removal of the sea cucumber from seawater. Rehydration of the dried products is necessary to obtain sea cucumbers with the highest water content. In this study, a rapid and non-invasive NMR and MRI method was introduced to analyze the rehydration process for dried sea cucumber. The spin–spin relaxation time (T2) weighted NMR signal, obtained by a CPMG pulse sequence and processed by the chemometric method, was used to identify lightly dried and salted dried sea cucumber. The water uptake and distribution during the rehydration process was monitored by NMR 1H T2. Structural changes were analyzed by MRI with T1 and T2 weighted imaging. The results indicated that the proper presoaking and rehydration time was 24 and 96 h, respectively, for lightly dried sea cucumber. Good linear correlation during the rehydration process was observed between the NMR parameters and texture profile analysis parameters including the hardness, chewiness, and rehydration ratio of lightly dried sea cucumbers. The NMR and MRI method has the potential to noninvasively analyze the rehydration process of dried sea cucumber.

Multifunctional Nanostructures for Tumor-Targeted Molecular Imaging and Photodynamic Therapy.

A multifunctional ICG-FA-PPD nanostructure is constructed by a facile self-assembly method through the negatively charged indocyanine green (ICG)- and positively charged folic acid-modified PEI-PEG-gadoteric acid (FA-PPD). The resulting ICG-FA-PPD is not only able to be used for targeting tumors, magnetic resonance imaging (MRI), and near-infrared imaging, but, more importantly, it enables photodynamic therapy for tumor.

A bimodal MRI and NIR liposome nanoprobe for tumor targeted molecular imaging

The combination of complementary MRI and NIR imaging methods evolved to provide an even more powerful bioimaging tool. Herein, a novel bimodal MRI/NIR nanoprobe GCF-HDA was prepared via a facile self-assembly approach of three types of amphiphilic structures in aqueous solution. The Stokes shift of the NIR moiety increased from 30 to 150 nm and fluorescence quantum yield increased from 1.5 to 8% after conjugation with electron-rich hexadecylamine (HDA) to organic dye Cy7. The photostability of the nanoprobe GCF-HDA was dramatically improved after involving the newly synthesized dye. Molecular dynamics simulation demonstrated that the GCF-HDA is composed of 2.0-3.5 nm clusters and in each cluster the head groups of the amphiphilic molecules assemble together and the tail groups point outwards. The r1 and r2 relaxivities of GCF-HDA were found to be 11.87 and 19.91 mM-1 s-1 per Gd(iii) chelate at 0.5 T, respectively. In vitro cellular imaging with human glioma U-87 MG cells showed that the GCF-HDA was able to enter the cells and accumulate in the cytoplasm. The targeted GCF-HDA resulted in higher MR contrast enhancement and stronger fluorescence intensity than the corresponding non-targeted probe GC-HDA in the tumor tissue 96 hours post injection. Ex vivo fluorescence imaging and histological analysis of the tumor tissue further confirmed the specific binding ability of the GCF-HDA.

Liposomal nanohybrid cerasomes for mitochondria-targeted drug delivery

Mitochondrial dysfunctions cause numerous human disorders and the development of mitochondria-targeted nanocarriers for drug delivery has aroused great attention. Herein, we report the synthesis of a liposomal nanohybrid cerasome modified with triphosphonium (TPP) for drug delivery to the mitochondrial matrix. The cerasomes were observed to possess an average size of about 38 nm in diameter, and the theoretical simulation of GBEMP mapping demonstrated that the amphiphilic organotrialkoxysilanes were stable as a bilayer equilibrium conformation after self-assembly. The cerasomes showed good stability, excellent biocompatibility and sustainable drug release behavior. Moreover, the TPP-targeted cerasomes resulted in greater drug accumulation in mitochondria, thus leading to a greater antitumor effect as compared to non-targeted cerasomes by using doxorubicin as a modal drug. The specific accumulation of TPP-targeted cerasomes within mitochondria was also confirmed by using JC-1 as the fluorescent probe to analyze the mitochondrial transmembrane potential change.

Use of low-field-NMR and MRI to characterize water mobility and distribution in pacific oyster (Crassostrea gigas) during drying process

ABSTRACT Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were used to monitor the water mobility and distribution of Pacific oyster during drying process. The results show the mobilities of bulk, immobilized, and free water were reduced, and the immobilized water was removed dramatically. T2-weighted images displayed the water decrease from the external surface to inner center of oyster during drying. In addition, excellent correlations between the total moisture content and T22 and A22 were observed with coefficients 0.9777 and 0.9832, respectively. Principal component analysis showed the drying degree of oyster could be monitored based on raw relaxation data. Thus, the result revealed that LF-NMR and MRI have great potential in assessing water mobility and distribution in oyster during drying process.

Non-destructive measurement of water and fat contents, water dynamics during drying and adulteration detection of intact small yellow croaker by low field NMR

Non-destructive and fast measurement and characterization of fish is highly desired during various processing treatment. In this study, water dynamics during drying process and adulteration with carrageen were detected using low field nuclear magnetic resonance (LF-NMR) technique in small yellow croaker. Prediction models of water and fat contents were established based on LF-NMR Carr–Purcell–Meiboom–Gill (CPMG) data combined with principal component regression (PCR) or partial least squares regression (PLSR). The Rcv2 of water and fat content by PLSR model was 0.9877 and 0.9054, and the root mean square error (RMSE) of cross-validation was 9.2360 and 3.3730%, respectively. Water dynamics during hot-air drying process showed that the amount of immobile water significantly decreased, and good correlation was found between the moisture ratio and peak area by Two-term model. In addition, the adulterated small yellow croaker with carrageen or distilled water could be clearly distinguished by principal component analysis (PCA) in a fast and non-destructive manner. All the results demonstrated that the LF-NMR may have great potential in fast and non-destructive analysis of small yellow croakers during various processing treatment.

Approach for monitoring the dynamic states of water in shrimp during drying process with LF-NMR and MRI

ABSTRACT The dynamic states of water in shrimp during drying process were investigated by low-field nuclear magnetic resonance and magnetic resonance imaging. With the extension of drying time, the transverse relaxation time of immobilized and free water significantly decreased, illustrating their mobility reduced. The signal per mass of immobilized water also decreased significantly, indicating its remarkable loss during drying process. Magnetic resonance imaging results revealed that the water signal intensity decreased from the external surface to inner regions of shrimp. Good correlations between the moisture content, hardness, chewiness, cohesiveness, L*, a* and nuclear magnetic resonance T2 parameters were observed by linear regression analysis.

Influence of multiple freeze-thaw cycles on quality characteristics of beef semimembranous muscle: With emphasis on water status and distribution by LF-NMR and MRI

Influences of multiple freeze-thaw (F-T) cycles on water status and distribution, microstructure and physicochemical properties of beef were investigated. Low-field nuclear magnetic resonance (LF-NMR) relaxation showed three water components were assigned to bound, immobilized and free water in beef matrix. With the increase of F-T cycles, the relaxation time and peak area of immobilized water decreased significantly (P < 0.05), which suggested the freedom and population of immobilized water decreased. T1 and T2 magnetic resonance images displayed a continuous decrease of water intensity in beef during multiple F-T cycles. The cryo-scanning electron microscopy results revealed repeated F-T cycles resulted in more and more large holes in the beef muscle fiber. The repeated F-T cycles also led to decrease of pH value, WHC, L* and a* values, hardness, springiness, cohesiveness and resilience, and the increase of thawing loss, cooking loss, b* and TBARS value. Partial least-squares regression models stated the potential of LF-NMR to predict the quality of beef as a non-destructive method.

Integration of Artificial Neural Network Modeling and Hyperspectral Data Preprocessing for Discrimination of Colla Corii Asini Adulteration

The study of hyperspectral imaging in tandem with spectral preprocessing and neural network techniques was conducted to realize Colla Corii Asini (CCA, E’jiao) adulteration discrimination. CCA was adulterated with pig skin gelatin (PSG) in the range of 5–95% (w/w) at 5% increments. Three methods were used to pretreat the original spectra, which are multiplicative scatter correction (MSC), Savitzky-Golay (SG) smoothing, and the combination of MSC and SG (MSC-SG). SPA was employed to select the characteristic wavelengths (CWs) to reduce the high dimension. Colour and texture features of CWs were extracted as input of prediction model. Two kinds of artificial neural network (ANN) with three spectral preprocessing methods were applied to establish the prediction models. The prediction model of generalized regression neural network (GRNN) in tandem with the MSC-SG preprocessed method presented satisfactory performance with the correct classification rate value of 92.5%. The results illustrated that the integration of preprocessing methods, hyperspectral imaging features, and ANN modeling had a great potential and feasibility for CCA adulteration discrimination.

Variable Temperature Nuclear Magnetic Resonance and Magnetic Resonance Imaging System as a Novel Technique for In Situ Monitoring of Food Phase Transition

A nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system with a 45 mm variable temperature (VT) sample probe (VT-NMR-MRI) was developed as an innovative technique for in situ monitoring of food phase transition. The system was designed to allow for dual deployment in either a freezing (-37 °C) or high temperature (150 °C) environment. The major breakthrough of the developed VT-NMR-MRI system is that it is able to measure the water states simultaneously in situ during food processing. The performance of the VT-NMR-MRI system was evaluated by measuring the phase transition for salmon flesh and hen egg samples. The NMR relaxometry results demonstrated that the freezing point of salmon flesh was -8.08 °C, and the salmon flesh denaturation temperature was 42.16 °C. The protein denaturation of egg was 70.61 °C, and the protein denaturation occurred at 24.12 min. Meanwhile, the use of MRI in phase transition of food was also investigated to gain internal structural information. All these results showed that the VT-NMR-MRI system provided an effective means for in situ monitoring of phase transition in food processing.