Decoding of quantum dots encoded microbeads using a hyperspectral fluorescence imaging method.

We presented a decoding method of quantum dots encoded microbeads with its fluorescence spectra using line scan hyperspectral fluorescence imaging (HFI) method. A HFI method was developed to attain both the spectra of fluorescence signal and the spatial information of the encoded microbeads. A decoding scheme was adopted to decode the spectra of multicolor microbeads acquired by the HFI system. Comparison experiments between the HFI system and the flow cytometer were conducted. The results showed that the HFI system has higher spectrum resolution; thus, more channels in spectral dimension can be used. The HFI system detection and decoding experiment with the single-stranded DNA (ssDNA) immobilized multicolor beads was done, and the result showed the efficiency of the HFI system. Surface modification of the microbeads by use of the polydopamine was characterized by the scanning electron microscopy and ssDNA immobilization was characterized by the laser confocal microscope. These results indicate that the designed HFI system can be applied to practical biological and medical applications.

Glycerol-mediated nanostructure modification leading to improved transparency of porous polymeric scaffolds for high performance 3D cell imaging.

Glycerol is among the most commonly used optical clearing agents for tissues clearance largely due to refractive index (RI) matching between glycerol and the submerged tissues. Here we applied glycerol as structure modifier at both macroscopic (as porogen) and nanoscopic (as nanostructure ameliorant) scales to fabricate transparent porous scaffolds made from poly(ethylene glycol) (PEG) as well as other widely used biomaterials (e.g., PLGA, PA, or gelatin), whose nanostructures, in the scale of light wavelength, dominantly improved the optical transmittance of the scaffolds even when immersed in RI mismatched medium (e.g., culture medium or water). We further exploited the clearing mechanisms based on Mie scattering theory, illustrating that conformational changes of polymer chains induced by solvent effects of glycerol enhanced the anisotropy (i.e., directional alignment) of the nanostructures, leading to reduced crystallinity and scattering of the resulted PEG scaffolds. Our findings represent the first and systematic demonstration with both experimental and theoretical evidence in effectively clearing porous polymeric scaffolds by mechanisms other than RI matching, which could tackle the limitations of current optical imaging of cells cultured within three-dimensional (3D) opaque porous scaffolds, such as poor visibility, low spatial resolution, and small penetration depth.

Two-dimensional backscattering Mueller matrix of sphere-cylinder scattering medium.

We present the experimental results for the two-dimensional backscattering Mueller matrix of a scattering medium containing polystyrene microspheres and silk fibers and simulate the same Mueller matrix using a polarization-sensitive Monte Carlo program with both layered and homogeneous sphere-cylinder scattering models. We discuss the characteristic features in each Mueller matrix element and their relations with the parameters of the spherical and cylindrical scatterers in the medium. Both experiments and simulations suggest that the Mueller matrix elements can be used to characterize the structural and optical properties of anisotropic scattering media.

Detection of Simulated Periradicular Lesions in Porcine Bone by Optical Coherence Tomography.

INTRODUCTION: The accurate detection of periradicular lesions located under a nonperforated cortical plate poses a challenge in endodontic microsurgery. Optical coherence tomography (OCT) is a noninvasive imaging method that has been successfully used in many dental applications. In this study, we investigated if spectral-domain OCT (SD-OCT) could be used to determine simulated periradicular lesions. METHODS: Twenty-eight cavities with different depths were prepared on bone plates obtained from 5 porcine mandibles. Both 3-dimensional SD-OCT imaging and micro-computed tomographic (micro-CT) imaging were used to image the bottom of the air-filled cavity and the cavity filled with soft tissue for comparison. The residual bone thickness under the cavity was measured by SD-OCT and micro-CT imaging and compared using the Pearson correlation. RESULTS: The air-filled lesions were readily detected; yet, filling of the cavity with soft tissue diminished the appearance of the lesion boundaries in the SD-OCT images. The optical values of residual bone thickness obtained from SD-OCT ranged from 0.14-2.11 mm, which corresponded to the range of 0.26-1.18 mm from micro-CT imaging. A strong correlation was found between the 2 imaging modalities (r = 0.96; range, 0.94-0.98). The slope (1.56) of the linear regression matched the bulk refractive index of bone tissues. CONCLUSIONS: SD-OCT allows for visualization of the lesion boundaries via intact bone surfaces and may be a promising, practical, and nonirradiating adjunct tool for chairside localization of periradicular lesions in bone.

[Construction of recombinant adenovirus vector carrying the mouse caveolin-1 in gene].

OBJECTIVE: To construct recombinant adenovirus carrying the mouse dentin caveolin-1 gene using the recombinant adenoviral vector system AdEasy. METHODS: The cDNA fragment of caveolin-1 was derived from pTRE2-caveolin-1 by restriction enzyme digestion and subcloned into shuttle plasmid pAdtrack-CMV. The resulting plasmid pAdtrack-CMV-caveolin-1, after linearized by digesting with restriction endonuclease Pme I, was transformed into E. coli 1 BJ5183 which had been transformed by adenoviral backbone plasmid pAdEasy-1. The recombinant plasmid pAd-caveolin-1 was screened by kanamycin LB plate and then identified by restriction enzyme digestion. The linearized adenovirus plasmid pAd-caveolin-1 was packaged in 293 cells, then the recombinant adenovirus Ad-caveolin-1 was harvested. The expression of green fluorescence protein was observed under fluorescent microscope. With further amplification and purification, the titer of recombinant adenovirus was determined. RESULTS: The recombinant adenovirus was identified by restriction enzyme digestion analysis and gene sequencing. Cytopathic effect and the expression of GFP were observed in the infected 293 cells. The sequence of caveolin-1 gene insert was the same as that published in the GenBank. The titer of the recombinant adenovirus was 2 x 10(9) pfu/mL. CONCLUSION: The mouse caveolin-1 recombinant adenovirus was constructed successfully by using AdEasy adenovirus system. Cell transfection and expression of exogenous gene can be detected directly by observing the expression of GFP. These results provide the basis for the further study on the role of caveolin-1 gene in other scopes.

Study on the influence of optical absorption on polarization characterization of tissues.

Absorption effect is a basic optical phenomenon and an important feature in tissue imaging and characterization. Based on our Monte Carlo simulation on the anisotropic tissue model (sphere-cylinder birefringence model), combined with our experiments of tissue phantoms, we demonstrate the influence of absorption effect on Mueller matrix and particularly on depolarization, linear retardance, and diattenuation parameters. The simulation and experimental results show a good consistency on the suppressed depolarization and scatterering induced retardance, and the enhanced diattenuation caused by the absorption, and also indicate the birefringence induced retardance insensitive to the absorption. Study of the phase function of different incident polarized lights and the distribution of scattering number gives a preliminary explanation about the above results.

Dual-channel-coded microbeads for multiplexed detection of biomolecules using assembling of quantum dots and element coding nanoparticles.

To achieve the dual-channel (analog and digital) encoding, microbeads assembled with quantum dots (QDs) and element coding nanoparticles (ECNPs) have been prepared. Dual-spectra, including fluorescence generated from quantum dots (QDs) and laser induced breakdown spectrum obtained from the plasma of ECNPs, including AgO, MgO and ZnO nanoparticles, has been adopted to provide more encoding amounts and more accurate dual recognition for encoded microbeads in multiplexed utilization. The experimental results demonstrate that the single microbead can be decoded in two optical channels. Multiplexed analysis and contrast adsorption experiment of anti-IgG verified the availability and specificity of dual-channel-coded microbeads in bioanalysis. In gradient detection of anti-IgG, we obtained the linear concentration response to target biomolecules from 3.125 × 10-10 M to 1 × 10-8 M, and the limit of detection was calculated to be 2.91 × 10-11 M.

Molecular imprinting sensor based on quantum weak measurement.

A new type of sensing protocol, based on a high precision metrology of quantum weak measurement, was first proposed for molecularly imprinted polymers (MIP) sensor. The feasibility, sensitivity and selectivity of weak measurement based MIP (WMMIP) sensor were experimentally demonstrated with bovine serum albumin (BSA). Weak measurement system exhibits high sensitivity to the optical phase shift corresponding to the refractive index change, which is induced by the specific capture of target protein molecules with its recognition sites. The recognition process can be finally characterized by the central wavelength shift of output spectra through weak value amplification. In our experiment, we prepared BSA@MIP with modified reversed-phase microemulsion method, and coated it on the internal surface of measuring channels assembled into the Mach-Zehnder (MZ) interferometer based optical weak measurement system. The design of this home-built optical system makes it possible to detect analyte in real time. The dynamic process of the specific adsorption and concentration response to BSA from 5×10-4 to 5×10-1µg/L was achieved with a limit of detection (LOD) of 8.01×10-12g/L. This WMMIP shows superiority in accuracy, fast response and low cost. Furthermore, real-time monitoring system can creatively promote the performance of MIP in molecular analysis.

Quantum-dots-encoded-microbeads based molecularly imprinted polymer.

Quantum dots encoded microbeads have various advantages such as large surface area, superb optical properties and the ability of multiplexing. Molecularly imprinted polymer that can mimic the natural recognition entities has high affinity and selectivity for the specific analyte. Here, the concept of utilizing the quantum dots encoded microbeads as the supporting material and the polydopamine as the functional monomer to form the core-shell molecular imprinted polymer was proposed for the first time. The resulted imprinted polymer can provide various merits: polymerization can complete in aqueous environment; fabrication procedure is facile and universal; the obvious economic advantage; the thickness of the imprinting layer is highly controllable; polydopamine coating can improve the biocompatibility of the quantum dot encoded microbeads. The rabbit IgG binding and flow cytometer experiment result showed the distinct advantages of this strategy: cost-saving, facile and fast preparation procedure. Most importantly, the ability for the multichannel detection, which makes the imprinted polydopamine modified encoded-beads very attractive in protein pre-concentration, recognition, separation and biosensing.

Effect of vitamin B12 on cleft palate induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and dexamethasone in mice.

The purpose of this study was to investigate the effect of vitamin B12 on palatal development by co-administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dexamethasone (DEX). We examined the morphological and histological features of the palatal shelf and expression levels of key signaling molecules (transforming growth factor-ß3 (TGF-ß3) and TGF-ß type I receptor (activin receptor-like kinase 5, ALK5)) during palatogenesis among a control group (Group A), TCDD+DEX exposed group (Group B), and TCDD+DEX+vitamin B12 exposed group (Group C). While we failed to find that vitamin B12 decreased the incidence of cleft palate induced by TCDD+DEX treatment, the expression levels of key signaling molecules (TGF-ß3 and ALK5) during palatogenesis were significantly modulated. In TCDD+DEX exposed and TCDD+DEX+vitamin B12 exposed groups, palatal shelves could not contact in the midline due to their small sizes. Our results suggest that vitamin B12 may inhibit the expression of some cleft palate inducers such as TGF-ß3 and ALK5 in DEX+TCDD exposed mice, which may be beneficial against palatogenesis to some degree, even though we were unable to observe a protective role of vitamin B12 in morphological and histological alterations of palatal shelves induced by DEX and TCDD.

Synergistic effect of ultrasound and thiazone-PEG 400 on human skin optical clearing in vivo.

In this paper, we propose a new physical method in combination with mixed solution of thiazone and polyethylene glycol 400 (thiazone PEG 400 solution) penetration into tissue to assess the skin optical clearing. Four treatments were performed: (1) control group (C); (2) polyethylene glycol 400 (PEG400); (3) 0.25% thiazone (0.25%T); (4) 0.25% thiazone and 5-min ultrasound (0.25%T/SP). The diffuse reflectance spectra and imaging depth of human skin in vivo at different times were measured by spectroscopy and optical coherence tomography (OCT). The optical clearing efficacy of skin was qualitatively and quantitatively analyzed. The results showed that the diffuse reflectance at 540 nm of samples at 10 min after being treated by 0.25%T/SP decreased by approximately 15.51%, whereas, 0.46%, 4.73% and 5.75% were received in C, PEG400 and 0.25%T, respectively. And at 60 min, the decrease in diffuse reflectance of samples in 0.25%T/SP is about 2.22-fold, 1.20-fold compared with that of the samples in PEG 400 and 0.25%T, at 540 nm, respectively. Simultaneously, 0.25%T/SP results in 41.33% increase in OCT 1/e light penetration depth after 60 min. There was a significant difference in the optical clearing effect on skin between ultrasound-mixed solution of thiazone in combination with PEG 400 and the mixed solution (P < 0.05).

Enhanced sensitivity and spatial resolution for in vivo imaging with low-level light-emitting probes by use of biocompatible chemical agents.

We describe a technique that uses biocompatible chemical agents to enhance both the sensitivity and the resolution of in vivo imaging with low-level light-emitting probes. We demonstrate experimentally, with chemiluminescence (CL) imaging in vitro as an example, that the detected intensity of CL from treated 3-mm-thick skin tissue is approximately fivefold stronger than that from untreated skin. The spatial resolution correspondingly increases approximately threefold.