Action-potential-encoded optical second harmonic generation (SHG) has been recently proposed for use in detecting the axonal damage in patients with demyelinating diseases. In this study, the characterization of signal conduction along axons of two different levels of demyelination was studied via a modified Hodgkin–Huxley model, because some types of demyelinating disease, i.e., primary progressive and secondary progressive multiple sclerosis, are difficult to be distinguished by magnetic resonance imaging (MRI), we focused on the differences in signal conduction between two different demyelinated axons, such as the first-level demyelination and the secondlevel demyelination. The spatio-temporal distribution of action potentials along demyelinated axons and conduction properties including the refractory period and frequency encoding in these two patterns were investigated. The results showed that demyelination could induce the decrease both in the amplitude of action potentials and the ability of frequency coding. Furthermore, the signal conduction velocity in the second-level demyelination was about 21% slower than that in the first-level demyelination. The refractory period in the second-level demyelination was about 32% longer than the first-level. Thus, detecting the signal conduction in demyelinated axons by action-potential-encoded optical SHG could greatly improve the assessment of demyelinating disorders to classify the patients. This technique also offers a potential fast and noninvasive optical approach for monitoring membrane potential.

We developed a model to describe polarized photon scattering in biological tissues. In this model, tissues are simplified to a mixture of scatterers and surrounding medium. There are two types of scatterers in the model: solid spheres and infinitely long solid cylinders. Variables related to the scatterers include: the densities and sizes of the spheres and cylinders, the orientation and angular distribution of cylinders. Variables related to the surrounding medium include: the refractive index, absorption coefficient and birefringence. In this paper, as a development we introduce an optical activity effect to the model. By comparing experiments and Monte Carlo simulations, we analyze the backscattering Mueller matrix patterns of several tissue-like media, and summarize the different effects coming from anisotropic scattering and optical properties. In addition, we propose a possible method to extract the optical activity values for tissues. Both the experimental and simulated results show that, by analyzing the Mueller matrix patterns, the microstructure and optical properties of the medium can be obtained. The characteristic features of Mueller matrix patterns are potentially powerful tools for studying the contrast mechanisms of polarization imaging for medical diagnosis.

Contrast agents are attracting a great deal of attention in photoacoustic imaging. Here we introduce an exogenous contrast agent that provides high photoacoustic signal amplitude at the near-infrared wavelength. Our agents consist of Indocyanine green (ICG) and phospholipid–polyethylene glycol (PL–PEG), entitled ICG–PL–PEG nanoparticles. These nanoparticles have overcome numerous limitations of ICG, such as poor aqueous stability, concentration-dependent aggregation and lack of target specificity. ICG–PL–PEG nanoparticles are biocompatible and relatively nontoxic. All the components of ICG–PL–PEG nanoparticles have been approved for human use. Upon pulsed laser irradiation, the nanoparticles are more efficient in producing photoacoustic waves than ICG alone. The results showed that ICG–PL–PEG nanoparticles act as good contrast agents for photoacoustic imaging. These unique ICG–PL–PEG nanoparticles have great potential in clinical applications.

A novel near-infrared light responsive microcapsule system, gold nanorod-covered DOX-loaded hollow CaCO₃ microcapsule (AuNR-HM-DOX) is developed for cancer therapy. The hollow CaCO₃ microcapsules were prepared based on the self-assembly between chitosan and sodium alginate on CaCO₃ particles via layer-by-layer technique, and then covered with gold nanorods to obtain the microcapsule system. Upon near-infrared (NIR) irradiation, microcapsule with gold nanorods can convert the absorbed NIR light into heat. Meanwhile, doxorubicin (DOX), a chemotherapy drug, is loaded into the microcapsule system via electrostatic adsorption for combined photothermal therapy and chemotherapy. Properties of AuNR-HM-DOX including grain diameter, optical spectra were characterized. Confocal fluorescence imaging was performed to observe the morphology of the capsules and existence of DOX in the core, confirming the successful loading of DOX. The release of DOX from the capsules under continuous NIR irradiation was investigated to evaluate the temperature responsiveness of AuNR-HM-DOX. Results indicate that AuNR-HM-DOX microcapsules possess uniform particle size and high light responsiveness. The combination of chemical and physical therapy of AuNR-HM-DOX features great potential as an adjuvant therapeutic alternative material for combined cancer therapy.

The synthesis of water-soluble quantum dots (QDs) has recently received extensive attention due to noninvasive detection of biological information in living subjects. In this paper, high-quality water-soluble (cadmium-free) quaternary AgZnInS QDs have been successfully synthesized using a green synthetic route. The as-prepared QDs exhibit tunable photoluminescence (PL) emission between 521 and 658 nm. Secondly, multidrug resistance (MDR) is a major impediment to the effective cancer chemotherapy. DOX, a widely used antitumor drug was modified on the surface of the QDs in this study. It, therefore, significantly enhanced the cytotoxicity of DOX to MDR cancer cells as the QDs could bring the DOX to nucleus.

Glycated hemoglobin (HbA1c) has been increasingly accepted as the gold standard for diabetes monitoring. In this study, Raman spectroscopy was tentatively employed for human hemoglobin (Hb) biochemical analysis aimed at developing a simple blood test for diabetes monitoring. Raman spectroscopy measurements were performed on hemoglobin samples of patients (n = 39) with confirmed diabetes and healthy volunteers (n = 37). The tentative assignments of the measured Raman bands were performed to compare the difference between these two groups. Meanwhile, principal component analysis (PCA) combined with linear discriminant analysis (LDA) were employed to develop effective diagnostic algorithms for classification between normal controls and patients with diabetes. As a result, the spectral features of these two groups demonstrated two distinct clusters with a sensitivity and specificity of 92.3% and 73%, respectively. Then the effectiveness of the diagnostic algorithm based on PCA-LDA technique was confirmed by receiver operating characteristic (ROC) curve. The area under the ROC curve was 0.92, indicating a good diagnostic result. In summary, our preliminary results demonstrate that proposing Raman spectroscopy can provide a significant potential for the noninvasive detection of diabetes.

Optical coherence tomography (OCT) enables in vivo imaging of port wine stains (PWS) lesions. The knowledge of vascular structure and epidermal thickness (ET) of PWS may aid the objective diagnosis and optimal treatment. To obtain the structural parameters more rapidly and avoid user intervention, an automated algorithm of energy map is introduced based on intensity and edge information to extract the skin surface using dynamic programming method. Subsequently, an averaged A-scan analysis is performed to obtain the mean ET and the relative intensity of dermis indicating the corresponding vascular density. This approach is currently successfully applied in clinical diagnosis and shows promising guidance and assessment of PDT treatment.

Microwave ablation (MWA) status monitoring in real time plays a key role in assessment of therapeutic effectiveness. As a novel real-time assessment method, near infrared spectroscopy (NIRs) was used to evaluate the ablation efficacy. MWA experiments were carried out on in vitro porcine livers. An optical measurement system for biological tissue is developed by our lab to monitor reduced scattering coefficient (μ^'_s) at 690 nm of the coagulation zones. It is noted that μ^'_s of liver tissue, which increases as the liver tissue being ablated, is clearly related with the coagulation status. μ^'_s of normal tissue and coagulated tissue is 3–5 and 17–19 cm^-1, respectively. Continuous changes of μ^'_s demonstrate that optical parameter can be used as an efficacy evaluation factor because it essentially indicates the degree of thermal damage. Compared with temperature, optical parameter is more sensitive and accurate, which is promising for real-time therapeutic efficacy assessment in MWA.

Multifocal multiphoton microscopy (MMM) has greatly improved the utilization of excitation light and imaging speed due to parallel multiphoton excitation of the samples and simultaneous detection of the signals, which allows it to perform three-dimensional fast fluorescence imaging. Stochastic scanning can provide continuous, uniform and high-speed excitation of the sample, which makes it a suitable scanning scheme for MMM. In this paper, the graphical programming language — LabVIEW is used to achieve stochastic scanning of the two-dimensional galvo scanners by using white noise signals to control the x and y mirrors independently. Moreover, the stochastic scanning process is simulated by using Monte Carlo method. Our results show that MMM can avoid oversampling or subsampling in the scanning area and meet the requirements of uniform sampling by stochastically scanning the individual units of the N × N foci array. Therefore, continuous and uniform scanning in the whole field of view is implemented.

Intracranial hemorrhage (IH) is a major problem of neonatal intensive care. The incidence of IH is typically asymptomatic and cannot be effectively detected by standard diagnostic methods. The mechanisms underlying IH are unknown but there is evidence that stress-induced disorders in adrenergic regulation of cerebral venous blood flow (CVBF) are among the main reasons. Quantitative and qualitative assessment of CVBF could significantly advance understanding of the nature of IH in newborns. In this work, we analyze variations of CVBF in newborn rats with an experimental model of stress-induced IH and adrenaline injection. Our analysis is based on the Doppler optical coherence tomography (DOCT) and a proposed adaptive wavelet-based approach that provides sensitive markers of abnormal reactions of the sagittal vein to external factors. The obtained results demonstrate that the incidence of IH in newborn rats is accompanied by a suppression of CVBF with the development of venous insufficiency and areactivity to adrenaline. We introduce a numerical measure θ, quantifying reactions of CVBF and show that the values θ < 1:23 estimated in the low-frequency (LF) spectral range corresponding to the sympathicus indicate abnormal reactions associated with the development of IH. We conclude that the revealed areactivity of the cerebral veins to adrenaline represents a possible mechanism responsible for pathological changes in CVBF.

Precisely distinguishing between hyperplastic and adenomatous polyps and normal human colonic mucosa at the cellular level is of great medical significance. In this work, multiphoton laser scanning microscopy (MPLSM) was used to obtain the high-contrast images and the morphological characteristics from normal colonic mucosa, hyperplastic polyps and tubular adenoma. By integrating the length and area measurement tools and computing tool, we quantified the difference of crypt morphology and the alteration of nuclei in normal and diseased human colonic mucosa. Our results demonstrated that the morphology of crypts had an obvious tendency to cystic dilatation or elongated in hyperplastic polyps and tubular adenoma. The content and number of mucin droplets of the scattered goblet cells had a piecemeal reduction in hyperplastic polyps and a large decrease in tubular adenoma. The nuclei of epithelial cells might be elongated and pseudostratified, but overt dysplasia was absent in hyperplastic polyps. Nevertheless, the nuclei showed enlarged, crowded, stratified and a rod-like structure, with loss of polarity in tubular adenoma. These results suggest that MPLSM has the capacity to distinguish between hyperplastic and adenomatous polyps and normal human colonic mucosa at the cellular level.

A leukocyte segmentation method based on S component and B component images is proposed. Threshold segmentation operation is applied to get two binary images in S component and B component images. The samples used in this study are peripheral blood smears. It is easy to find from the two binary images that gray values are the same at every corresponding pixels in the leukocyte cytoplasm region, but opposite in the other regions. The feature shows that "IMAGE AND" operation can be employed on the two binary images to segment the cytoplasm region of leukocyte. By doing "IMAGE XOR" operation between cytoplasm region and nucleus region, the leukocyte segmentation can be retrieved effectively. The segmentation accuracy is evaluated by comparing the segmentation result of the proposed method with the manual segmentation by a hematologist. Experiment results show that the proposed method is of a higher segmentation accuracy and it also performs well when leukocytes overlap with erythrocytes. The average segmentation accuracy of the proposed method reaches 97.7% for segmenting five types of leukocyte. Good segmentation results provide an important foundation for leukocytes automatic recognition.

A novel hemodynamic model has been recently introduced, which provides analytical relationships between the changes in cerebral blood volume (CBV), cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO₂), and associated changes in the tissue concentrations of oxy- and deoxy-hemoglobin (△O and △D) measured with near-infrared spectroscopy (NIRS) [S. Fantini, Neuroimage 85, 202–221 (2014)]. This novel model can be applied to measurements of the amplitude and phase of induced hemodynamic oscillations as a function of the frequency of oscillation, realizing the novel technique of coherent hemodynamics spectroscopy (CHS) [S. Fantini, Neuroimage 85, 202–221 (2014); M. L. Pierro et al., Neuroimage 85, 222–233 (2014)]. In a previous work, we have demonstrated an in vivo application of CHS on human subjects during paced breathing [M. L. Pierro et al., Neuroimage 85, 222–233 (2014)]. In this work, we present a new analysis of the collected data during paced breathing based on a slightly revised formulation of the hemodynamic model and an efficient fitting procedure. While we have initially treated all 12 model parameters as independent, we have found that, in this new implementation of CHS, the number of independent parameters is eight. In this article, we identify the eight independent model parameters and we show that our previous results are consistent with the new formulation, once the individual parameters of the earlier analysis are combined into the new set of independent parameters.

We developed a biosensor that is capable for simultaneous surface plasmon resonance (SPR) sensing and hyperspectral fluorescence analysis in this paper. A symmetrical metal-dielectric slab scheme is employed for the excitation of coupled plasmon waveguide resonance (CPWR) in the present work. Resonance between surface plasmon mode and the guided waveguide mode generates narrower full width half-maximum of the reflective curves which leads to increased precision for the determination of refractive index over conventional SPR sensors. In addition, CPWR also offers longer surface propagation depths and higher surface electric field strengths that enable the excitation of fluorescence with hyperspectral technique to maintain an appreciable signal-to-noise ratio. The refractive index information obtained from SPR sensing and the chemical properties obtained through hyperspectral fluorescence analysis confirm each other to exclude false-positive or false-negative cases. The sensor provides a comprehensive understanding of the biological events on the sensor chips.

Finding subtypes of cancer in breast cancer database is an extremely difficult task because of heavy noise by measurement error. Most of the recent clustering techniques for breast cancer database to achieve cancerous and noncancerous often weigh down the interpretability of the structure. Hence, this paper tries to find effective Fuzzy C-Means-based clustering techniques to identify the proper subtypes of cancer in breast cancer database. This paper obtains the objective function of effective Fuzzy C-Means clustering techniques by incorporating the kernel induced distance function, Renyi's entropy function, weighted distance measure and neighborhood termsbased spatial context. The effectiveness of the proposed methods are proved through the experimental works on Lung cancer database, IRIS dataset, Wine dataset, Checkerboard dataset, Time Series dataset and Yeast dataset. Finally, the proposed methods are implemented successfully to cluster the breast cancer database into cancerous and noncancerous. The clustering accuracy has been validated through error matrix and silhouette method.