Zhengfei Zhuang

Study of molecule variations in renal tumor based on confocal micro-Raman spectroscopy

Abstract. Confocal micro-Raman spectroscopy—a valuable analytical tool in biological and medical field of research—allows probing molecular vibrations of samples without external labels or extensive preparation. We employ confocal micro-Raman spectroscopy to characterize renal tumors and normal tissue. Results show that Raman peaks of the renal tumor at 788 and 1087  cm−1, which belong to νsPO2− and νasPO2− stretching, respectively, have an obvious increase. At the same time, the ratio of I855/I831 in renal tumor tissue is 1.39±0.08, while that in normal renal tissue is 2.44±0.05 (p<0.01). This means that more tyrosine conformation transform from “buried” to “exposed” in the presence of cancer. Principal component analysis is used to classify the Raman spectra of renal tumor tissue and normal tissue.

Multifunctional Nanoplatform Based on Black Phosphorus Quantum Dots for Bioimaging and Photodynamic/Photothermal Synergistic Cancer Therapy

A multifunctional nanoplatform based on black phosphorus quantum dots (BPQDs) was developed for cancer bioimaging and combined photothermal therapy (PTT) and photodynamic therapy (PDT). BPQDs were functionalized with PEG chains to achieve improved biocompatibility and physiological stability. The as-prepared nanoparticles exhibite prominent near-infrared (NIR) photothermal and red-light-triggered photodynamic properties. The combined therapeutic application of PEGylated BPQDs were then performed in vitro and in vivo. The results demonstrate that the combined phototherapy significantly promote the therapeutic efficacy of cancer treatment in comparison with PTT or PDT alone. BPQDs could also serve as the loading platform for fluorescent molecules, allowing reliable imaging of cancer cells. In addition, the low cytotoxicity and negligible side effects to main organs were observed in toxicity experiments. The theranostic characteristics of PEGylated BPQDs provide an uplifting potential for the future clinical applications.

Quantitative optical coherence tomography of skin lesions induced by different ultraviolet B sources

Ultraviolet B (UVB) has been widely used in dermatological phototherapy. Narrowband UVB (NB-UVB), with a peak at 311 nm, is considered to be more effective than broadband UVB (BB-UVB). However, the safety of NB-UVB is controversial. In this study, we first introduced optical coherence tomography (OCT), a novel, non-invasive in vivo imaging technology, to assess the effect of NB-UVB and BB-UVB on skin. Balb/c mice dorsal skin was exposed with increasing UVB doses (1MED, 3MEDs and 5MEDs), and then OCT images of the tissues were obtained by an OCT system with 1310 nm central wavelength. Quantitative parameters (skin thickness, disruption of the entrance signal and correlation coefficient) were extracted from the OCT images. The data indicated that NB-UVB-induced skin lesions were similar to that of BB-UVB at 1MED or 3MEDs UVB. However, the skin tissues exposed with 5MEDs NB-UVB suffered from more lesions than BB-UVB. Furthermore, the persistence of skin inflammation in 3MEDs NB-UVB-induced skin tissues was much longer than that of BB-UVB (P = 0.004). In conclusion, optimized treatment time and frequency as well as close clinical monitoring should be undertaken to reduce the latent risk of NB-UVB phototherapy.

Micro-Raman spectroscopy study of the effect of Mid-Ultraviolet radiation on erythrocyte membrane.

Mid-Ultraviolet (UVB) has a significant influence on human health. In this study, human erythrocytes were exposed to UVB to investigate the effects of UVB radiation on erythrocytes membrane. And Micro-Raman spectroscopy was employed to detect the damage. Principal component analysis (PCA) was used to classify the control erythrocytes and the irradiated erythrocytes. Results showed that the erythrocytes membrane was damaged by Mid-Ultraviolet (UVB) radiation. The intensity of the Raman peaks at 1126 cm(-1) and 1082 cm(-1) were used to calculate the Longitudinal Order-Parameters in Chains (S(trans)) which can present the liquidity and ionic permeability of erythrocyte membrane. After UVB radiation for 30 min, both the liquidity and ionic permeability decreased. At the same time, the intensity of the peaks at 1302 cm(-1) (α-helix), 1254 cm(-1) (random coil), 1452 cm(-1) and 1430 cm(-1) (CH(2)/CH(3) stretch) have also changed which indicated the membrane protein also been damaged by UVB. In the whole process of radiation, the more UVB radiation dose the more damage on the erythrocyte membrane.

Study of molecule variation in various grades of human nuclear cataracts by confocal micro-Raman spectroscopy

Confocal micro-Raman spectroscopy is employed to characterize various grades of human cataracts. Results show that the intensity ratio of the tyrosine doublet (I855/I833) changes from 1:1.07 ± 0.03 to 1:1.17 ± 0.05 with the aggravation of cataracts, which indicates that there are more tyrosine residues bound to strong H acceptors instead of bounding to water. The decrease of relative intensity at 880 cm−1 band suggests that the “buried” tryptophan residues become “exposed” during the course of lens opacification. A three-dimensional principal component analysis is used to classify the Raman spectra of opacity tissues, which show a one-to-one correspondence with different grades of cataracts.

Discrimination of dimethyl sulphoxide diffusion coefficient in the process of optical clearing by confocal micro-Raman spectroscopy

Abstract. Confocal micro-Raman spectroscopy is employed to study the diffusion process of dimethyl sulfoxide (DMSO) in porcine skin optical clearing. The variation of DMSO concentration with time at different depths of the skin was obtained and then the DMSO diffusion coefficient with the passive diffusion model was calculated. Results show that it has a significant difference at different depths of the skin. Also, the DMSO concentration with the depth at different times was obtained and the same method was used to find the change law of the DMSO diffusion coefficient. Results indicate that it also changes with the treatment time. The experimental results are consistent with the theoretical model in a previous study. The current results demonstrate that Raman spectroscopy has the ability to quantitatively monitor the process of optical clearing.

Detection of methemoglobin in whole blood based on confocal micro-raman spectroscopy and multivariate statistical techniques

Raman spectroscopy has been shown to have the potential for revealing oxygenated and spin ability of hemoglobin. In this study, confocal micro-Raman spectroscopy is developed to monitor the effect of sodium nitrite on oxyhemoglobin (HbO2 ) in whole blood. We observe that the band at 1,638 cm(-1) which is sensitive to the oxidation state decreases dramatically, while the 1,586 cm(-1) (low-spin state band) reduces both in methemoglobin (MetHb) and poisoning blood. Our results show that adding in sodium nitrite lead to the transition from HbO2 (Fe(2+) ) to MetHb (Fe(3+) ) in whole blood, and the iron atom converts from the low spin state to the high spin state with a delocalization from porphyrin plane. Moreover, multivariate statistical techniques, including principal components analysis (PCA) and linear discriminant analysis (LDA) are employed to develop effective diagnostic algorithms for classification of spectra between pure blood and poisoning blood. The diagnostic algorithms based on PCA-LDA yield a diagnostic sensitivity of 100% and specificity of 100% for separating poisoning blood from normal blood. Receiver operating characteristic (ROC) curve further confirms the effectiveness of the diagnostic algorithm based on PCA-LDA technique. The results from this study demonstrate that Raman spectroscopy combined with PCA-LDA algorithms has tremendous potential for the non-invasive detection of nitrite poisoning blood.

Simulation study of second-harmonic microscopic imaging signals through tissue-like turbid media.

We establish, for the first time, a simulation model for dealing with the second-harmonic signals under a microscope through a tissue-like turbid medium, based on the Monte Carlo method. With this model, the angle-resolved distribution and the signal level eta of second-harmonic light through a slab of the turbid medium are demonstrated and the effects of the thickness (d) of the turbid medium, the numerical aperture (NA) of the objective as well as the size (rho) of the scatterers forming the turbid medium are explored. Simulation results reveal that the use of a small objective NA results in a narrow angle distribution but strong second-harmonic signals. A turbid medium consisting of large scattering particles has a strong influence on the angle distribution and the signal level eta, which results in a low penetration limit for second-harmonic signals made up of ballistic photons. It is approximately 30 microm in our situation.

Second Harmonic Generation in 3-D Uniform Arrangement of Type I Collagen on Nonlinear Optics Microscopy

Second harmonic microscopic imaging and spectroscopy technology has become a powerful tool for biomedical studies, especially in fibrosis-related diseases research. And type I collagen is the major risk factors for fibrotic diseases. In this study, model for three-dimensional (3-D) uniform arrangement type I collagen is set up for researching the second harmonic generation (SHG) on nonlinear optics microscopy. Based on this model, we discuss the influence of different length and size collagen in 3-D arrangement type I collagen. Results can guide us to neatly judge the size, length, and molecules density effect on SHG. For practical application, this theoretical approach can lead us to analyze different severity of collagen diseases.

Application of surface-enhanced Raman in skin cancer by plasma

We have developed a mouse squamous cell carcinomas (SCC) model by diniethylbenzanthracene (DMBA) and ultraviolet (UVB). A silver colloid as SERS-active substrates is used for detecting the blood plasma of mouse. The relative intensity of the band at 942 and 1499 cm−1 is higher in SCC model than in healthy one. Therefore, it can be used as an important “fingerprint” in order to diagnose these diseases. Results show us how to get high signal-to-noise ratio of biological macromolecules surface-enhanced Raman scattering spectra in blood plasma. And also offer useful help for understanding the rich molecular structure information in biological tissues. It provides a molecular spectroscopy way for early detection of disease in blood plasma.