Zufang Huang

Nasopharyngeal cancer detection based on blood plasma surface-enhanced Raman spectroscopy and multivariate analysis

A surface-enhanced Raman spectroscopy (SERS) method was developed for blood plasma biochemical analysis for the first time with the aim to develop a simple blood test for non-invasive nasopharyngeal cancer detection. Silver nanoparticles (Ag NP) as the SERS-active nanostructures were directly mixed with blood plasma to enhance the Raman scattering signals of various biomolecular constituents such as proteins, lipids, and nucleic acids. High quality SERS spectrum from blood plasma-Ag NP mixture can be obtained within 10s using a Renishaw micro-Raman system. SERS measurements were performed on two groups of blood plasma samples: one group from patients (n=43) with pathologically confirmed nasopharyngeal carcinomas (WHO type I, II, and III) and the other group from healthy volunteers (control subjects, n=33). Tentative assignments of the Raman bands in the measured SERS spectra suggest interesting cancer specific biomolecular differences, including an increase in the relative amounts of nucleic acid, collagen, phospholipids and phenylalanine and a decrease in the percentage of amino acids and saccharide contents in the blood plasma of nasopharyngeal cancer patients as compared to that of healthy subjects. Principal component analysis (PCA) of the measured SERS spectra separated the spectral features of the two groups into two distinct clusters with little overlaps. Linear discriminate analysis (LDA) based on the PCA generated features differentiated the nasopharyngeal cancer SERS spectra from normal SERS spectra with high sensitivity (90.7%) and specificity (100%). The results from this exploratory study demonstrated great potentials for developing SERS blood plasma analysis into a novel clinical tool for non-invasive detection of nasopharyngeal cancers.

Cu-doped GaN: A dilute magnetic semiconductor from first-principles study

First-principles calculations based on spin density functional theory are performed to study the spin-resolved electronic properties of GaN doped with 6.25% of Cu. The Cu dopants are found spin polarized and the calculated band structures suggest a 100% polarization of the conduction carriers. The Cu-doped GaN favors ferromagnetic ground state which can be explained in terms of p‐d hybridization mechanism, and a Curie temperature around 350K can be expected. These results suggest that the Cu-doped GaN is a promising dilute magnetic semiconductor free of magnetic precipitates and may find applications in the field of spintronics.

Ferromagnetism in Mg-doped AlN from ab initio study

Ab initio calculations based on spin density functional theory were carried out to investigate Mg-doped AlN as a possible dilute magnetic semiconductor. It was found that both Al vacancy and substitutional Mg impurity in AlN lead to spin-polarized ground states. However, sufficient Al vacancy concentration may be difficult to achieve under thermal equilibrium because of the high formation energy of Al vacancy. On the other hand, formation energy of Mg defect is fairly low and the authors’ calculations predict a ferromagnetic coupling among MgN4 tetrahedra. Based on the analysis on Cu-doped ZnO [L. H. Ye et al., Phys. Rev. B 73, 033203 (2006)], room temperature ferromagnetism can be expected in AlN doped with 7% of Mg which can be incorporated at a growth temperature of 2000K under N-rich condition.

A novel blood plasma analysis technique combining membrane electrophoresis with silver nanoparticle-based SERS spectroscopy for potential applications in noninvasive cancer detection

Combining membrane electrophoresis with silver nanoparticle-based surface-enhanced Raman spectroscopy (SERS), we have developed a novel method for blood plasma analysis for cancer detection applications. In this method, total serum proteins are isolated from blood plasma by membrane electrophoresis and mixed with silver nanoparticles to perform SERS spectral analysis. The obtained SERS spectra present information-rich, fingerprint-type signatures of the biochemical constituents of whole proteins. We evaluated the utility of this method by analyzing blood plasma samples from patients with gastric cancer (n=31) and healthy volunteers (n=33). Principal components analysis of the spectra revealed that the data points for the two groups form distinct, completely separated clusters with no overlap. The gastric cancer group can be unambiguously distinguished from the normal group in this initial test-that is, with both diagnostic sensitivity and specificity of 100%. These results are very promising for developing a label-free, noninvasive clinical tool for cancer detection and screening.

Gold nanoparticle based surface-enhanced Raman scattering spectroscopy of cancerous and normal nasopharyngeal tissues under near-infrared laser excitation.

The capabilities of using gold nanoparticle based near-infrared surface-enhanced Raman scattering (SERS) to obtain biochemical information with high spatial resolution from human nasopharyngeal tissue were presented in this paper. The gold nanoparticles used have a mean diameter of 43 nm with a standard deviation of 6 nm. The SERS bands of nasopharyngeal tissue were assigned to known molecular vibrations of nucleic acids, amino acids, proteins, and metabolites. We also observed the blinking phenomenon at the tissue level when measuring the nasopharyngeal tissue SERS spectra, most frequently in signal intensity but also occasionally in peak positions. This phenomenon is excitation light intensity dependent. This work demonstrated great potential for using SERS imaging for distinguishing cancerous and normal nasopharyngeal tissues on frozen sections without using any dye labeling or other chemical species as functionalized binding sites.

Converse magnetoelectric effect in ferromagnetic shape memory alloy/piezoelectric laminate

In laminates, the converse magnetoelectric (CME) effect is often achieved by an elastic coupling between magnetostrictive and piezoelectric layers. Here the authors report on an alternative mechanism for obtaining CME. In a transition-metals-based ferromagnetic shape memory alloy/piezoelectric ceramic laminated composite, the stress-induced martensitic transformation is utilized to gain the magnetic changes, which gives rise to a giant CME effect consequently. The strong CME is observed at room temperature over a broad bandwidth, under weak magnetic bias and electric field.

Esophageal cancer detection based on tissue surface-enhanced Raman spectroscopy and multivariate analysis

The capability of using silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) spectroscopy combined with principal component analysis (PCA) and linear discriminate analysis (LDA) to differentiate esophageal cancer tissue from normal tissue was presented. Significant differences in Raman intensities of prominent SERS bands were observed between normal and cancer tissues. PCA-LDA multivariate analysis of the measured tissue SERS spectra achieved diagnostic sensitivity of 90.9% and specificity of 97.8%. This exploratory study demonstrated great potential for developing label-free tissue SERS analysis into a clinical tool for esophageal cancer detection.

Label-free serum ribonucleic acid analysis for colorectal cancer detection by surface-enhanced Raman spectroscopy and multivariate analysis

Studies with circulating ribonucleic acid (RNA) not only provide new targets for cancer detection, but also open up the possibility of noninvasive gene expression profiling for cancer. In this paper, we developed a surface-enhanced Raman scattering (SERS), platform for detection and differentiation of serum RNAs of colorectal cancer. A novel three-dimensional (3-D), Ag nanofilm formed by dry MgSO(4) aggregated silver nanoparticles, Ag NP, as the SERS-active substrate was presented to effectively enhance the RNA Raman signals. SERS measurements were performed on two groups of serum RNA samples. One group from patients, n=55 with pathologically diagnosed colorectal cancer and the other group from healthy controls, n=45. Tentative assignments of the Raman bands in the normalized SERS spectra demonstrated that there are differential expressions of cancer-related RNAs between the two groups. Linear discriminate analysis, based on principal component analysis, generated features can differentiate the colorectal cancer SERS spectra from normal SERS spectra with sensitivity of 89.1 percent and specificity of 95.6 percent. This exploratory study demonstrated great potential for developing serum RNA SERS analysis into a useful clinical tool for label-free, noninvasive screening and detection of colorectal cancers.

Cu-doped AlN: a dilute magnetic semiconductor free of magnetic cations from first-principles study

The spin-resolved electronic structure of AlN doped with 6.25% Cu has been studied by first-principles calculations based on spin density functional theory. A single substitutional Cu impurity and its nearest neighbouring N atoms have a spin polarized state with a global magnetization of 2.00 μB. Band structures show a half metallic behaviour of Cu-doped AlN. Cu-doped AlN has a ferromagnetic ground state which can be explained by a p–d hybridization mechanism. These results indicate that Cu-doped AlN shows promise as a dilute magnetic semiconductor (DMS). This study give new clues to the fabrication of DMSs.

Raman spectroscopic characterization and differentiation of seminal plasma.

Raman spectroscopy (RS) was applied for the analysis of seminal plasma in order to detect spectral parameters, which might be used for differentiating the normal and abnormal semen samples. Raman spectra of seminal plasma separated from normal and abnormal semen samples, showed a distinct difference in peak ratios between 1449 and 1418 cm(-1) (P < 0.05). More efficient alternative method of using principal component analysis-linear discriminate analysis based on Raman spectroscopic data yielded a diagnostic sensitivity of 73% and specificity of 82%. The results suggest that RS combined with the multivariate analysis method has the potential for differentiating semen samples by examination of the corresponding seminal plasma.