Quencher-free fluorescent assays by controlled DNA partitioning in the aqueous two-phase system with crowding-enhanced kinetics.

Fluorescent DNA assays are promising in disease diagnosis, environmental monitoring, and drug screening, encompassing both heterogeneous and homogeneous assay types. Nevertheless, heterogeneous assays suffer from tedious washing steps and slow reaction kinetics, whereas homogenous assays require well-designed fluorophore pairs to modulate signal off/on. Herein, we developed a cost-effective and efficient quencher-free fluorescent DNA assay using an aqueous two-phase system (ATPS). Using a strand-displacement reaction, we showed that similar sensing performance could be achieved at a much lower cost. Furthermore, the unique crowding environment in ATPS accelerated strand-displacement reactions by up to six-fold and reduced DNA amplification time from 120 min to 30 min. Our assay demonstrated robust sensing in serum environments and successful detection of miRNA extracted from cells. This innovative assay format has the potential for biosensor development with both heterogeneous readout and rapid reaction kinetics in various applications.

Sparse2Noise: Low-dose synchrotron X-ray tomography without high-quality reference data.

BACKGROUND: Synchrotron radiation computed tomography (SR-CT) holds promise for high-resolution in vivo imaging. Notably, the reconstruction of SR-CT images necessitates a large set of data to be captured with sufficient photons from multiple angles, resulting in high radiation dose received by the object. Reducing the number of projections and/or photon flux is a straightforward means to lessen the radiation dose, however, compromises data completeness, thus introducing noises and artifacts. Deep learning (DL)-based supervised methods effectively denoise and remove artifacts, but they heavily depend on high-quality paired data acquired at high doses. Although algorithms exist for training without high-quality references, they struggle to effectively eliminate persistent artifacts present in real-world data. METHODS: This work presents a novel low-dose imaging strategy namely Sparse2Noise, which combines the reconstruction data from paired sparse-view CT scan (normal-flux) and full-view CT scan (low-flux) using a convolutional neural network (CNN). Sparse2Noise does not require high-quality reconstructed data as references and allows for fresh training on data with very small size. Sparse2Noise was evaluated by both simulated and experimental data. RESULTS: Sparse2Noise effectively reduces noise and ring artifacts while maintaining high image quality, outperforming state-of-the-art image denoising methods at same dose levels. Furthermore, Sparse2Noise produces impressive high image quality for ex vivo rat hindlimb imaging with the acceptable low radiation dose (i.e., 0.5 Gy with the isotropic voxel size of 26 µm). CONCLUSIONS: This work represents a significant advance towards in vivo SR-CT imaging. It is noteworthy that Sparse2Noise can also be used for denoising in conventional CT and/or phase-contrast CT.

Highly Uniform DNA Monolayers Generated by Freezing-Directed Assembly on Gold Surfaces Enable Robust Electrochemical Sensing in Whole Blood.

Assembling DNA on solid surfaces is fundamental to surface-based DNA technology. However, precise control over DNA conformation and organization at solid-liquid interfaces remains a challenge, resulting in limited stability and sensitivity in biosensing applications. We herein communicate a simple and robust method for creating highly uniform DNA monolayers on gold surfaces by a freeze-thawing process. Using Raman spectroscopy, fluorescent imaging, and square wave voltammetry, we demonstrate that thiolated DNA is concentrated and immobilized on gold surfaces with an upright conformation. Moreover, our results reveal that the freezing-induced DNA surfaces are more uniform, leading to improved DNA stability and target recognition. Lastly, we demonstrate the successful detection of a model drug in undiluted whole blood while mitigating the effects of biofouling. Our work not only provides a simple approach to tailor the DNA-gold surface for biosensors but also sheds light on the unique behavior of DNA oligonucleotides upon freezing on the liquid-solid interface.

A facile method for purifying DNA-modified small particles and soft materials using aqueous two-phase systems.

We herein report a convenient and effective method for the purification of DNA-conjugated materials with a benchtop minicentrifuge. We demonstrate the fast isolation of DNA-modified small gold nanoparticles (5 nm), liposomes, and DNA nanostructures using fluorescent methods and gel electrophoresis. Our method is cost-effective and efficient and would accelerate the development of DNA nanotechnology.

Optimization of 3D printing and in vitro characterization of alginate/gelatin lattice and angular scaffolds for potential cardiac tissue engineering.

Background: Engineering cardiac tissue that mimics the hierarchical structure of cardiac tissue remains challenging, raising the need for developing novel methods capable of creating structures with high complexity. Three-dimensional (3D)-printing techniques are among promising methods for engineering complex tissue constructs with high precision. By means of 3D printing, this study aims to develop cardiac constructs with a novel angular structure mimicking cardiac architecture from alginate (Alg) and gelatin (Gel) composite. The 3D-printing conditions were optimized and the structures were characterized in vitro, with human umbilical vein endothelial cells (HUVECs) and cardiomyocytes (H9c2 cells), for potential cardiac tissue engineering. Methods: We synthesized the composites of Alg and Gel with varying concentrations and examined their cytotoxicity with both H9c2 cells and HUVECs, as well as their printability for creating 3D structures of varying fibre orientations (angular design). The 3D-printed structures were characterized in terms of morphology by both scanning electron microscopy (SEM) and synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT), and elastic modulus, swelling percentage, and mass loss percentage as well. The cell viability studies were conducted via measuring the metabolic activity of the live cells with MTT assay and visualizing the cells with live/dead assay kit. Results: Among the examined composite groups of Alg and Gel, two combinations with ratios of 2 to 1 and 3 to 1 (termed as Alg2Gel1 and Alg3Gel1) showed the highest cell survival; they accordingly were used to fabricate two different structures: a novel angular and a conventional lattice structure. Scaffolds made of Alg3Gel1 showed higher elastic modulus, lower swelling percentage, less mass loss, and higher cell survival compared to that of Alg2Gel1. Although the viability of H9c2 cells and HUVECs on all scaffolds composed of Alg3Gel1 was above 99%, the group of the constructs with the angular design maintained significantly more viable cells compared to other investigated groups. Conclusion: The group of angular 3D-ptinted constructs has illustrated promising properties for cardiac tissue engineering by providing high cell viability for both endothelial and cardiac cells, high mechanical strength as well as appropriate swelling, and degradation properties during 21 days of incubation. Statement of Significance: 3D-printing is an emerging method to create complex constructs with high precision in a large scale. In this study, we have demonstrated that 3D-printing can be used to create compatible constructs from the composite of Alg and Gel with endothelial cells and cardiac cells. Also, we have demonstrated that these constructs are able to enhance the viability of cardiac and endothelial cells via creating a 3D structure mimicking the alignment and orientation of the fibers in the native heart.

Low-density tissue scaffold imaging by synchrotron radiation propagation-based imaging computed tomography with helical acquisition mode.

Visualization of low-density tissue scaffolds made from hydrogels is important yet challenging in tissue engineering and regenerative medicine (TERM). For this, synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT) has great potential, but is limited due to the ring artifacts commonly observed in SR-PBI-CT images. To address this issue, this study focuses on the integration of SR-PBI-CT and helical acquisition mode (i.e. SR-PBI-HCT) to visualize hydrogel scaffolds. The influence of key imaging parameters on the image quality of hydrogel scaffolds was investigated, including the helical pitch (p), photon energy (E) and the number of acquisition projections per rotation/revolution (Np), and, on this basis, those parameters were optimized to improve image quality and to reduce noise level and artifacts. The results illustrate that SR-PBI-HCT imaging shows impressive advantages in avoiding ring artifacts with p = 1.5, E = 30 keV and Np = 500 for the visualization of hydrogel scaffolds in vitro. Furthermore, the results also demonstrate that hydrogel scaffolds can be visualized using SR-PBI-HCT with good contrast while at a low radiation dose, i.e. 342 mGy (voxel size of 26 µm, suitable for in vivo imaging). This paper presents a systematic study on hydrogel scaffold imaging using SR-PBI-HCT and the results reveal that SR-PBI-HCT is a powerful tool for visualizing and characterizing low-density scaffolds with a high image quality in vitro. This work represents a significant advance toward the non-invasive in vivo visualization and characterization of hydrogel scaffolds at a suitable radiation dose.

Bioprinting of alginate-carboxymethyl chitosan scaffolds for enamel tissue engineeringin vitro.

Tissue engineering offers a great potential in regenerative dentistry and to this end, three dimensional (3D) bioprinting has been emerging nowadays to enable the incorporation of living cells into the biomaterials (such a mixture is referred as a bioink in the literature) to create scaffolds. However, the bioinks available for scaffold bioprinting are limited, particularly for dental tissue engineering, due to the complicated, yet compromised, printability, mechanical and biological properties simultaneously imposed on the bioinks. This paper presents our study on the development of a novel bioink from carboxymethyl chitosan (CMC) and alginate (Alg) for bioprinting scaffolds for enamel tissue regeneration. CMC was used due to its antibacterial ability and superior cell interaction properties, while Alg was added to enhance the printability and mechanical properties as well as to regulate the degradation rate. The bioinks with three mixture ratios of Alg and CMC (2-4, 3-3 and 4-2) were prepared, and then printed into the calcium chloride crosslinker solution (100 mM) to form a 3D structure of scaffolds. The printed scaffolds were characterized in terms of structural, swelling, degradation, and mechanical properties, followed by theirin vitrocharacterization for enamel tissue regeneration. The results showed that the bioinks with higher concentrations of Alg were more viscous and needed higher pressure for printing; while the printed scaffolds were highly porous and showed a high degree of printability and structural integrity. The hydrogels with higher CMC ratios had higher swelling ratios, faster degradation rates, and lower compressive modulus. Dental epithelial cell line, HAT-7, could maintain high viability in the printed constructs after 1, 7 and 14 d of culture. HAT-7 cells were also able to maintain their morphology and secrete alkaline phosphatase after 14 d of culture in the 3D printed scaffolds, suggesting the capacity of these cells for mineral deposition and enamel-like tissue formation. Among all combinations Alg4%-CMC2% and in a less degree 2%Alg-4%CMC showed the higher potential to promote ameloblast differentiation, Ca and P deposition and matrix mineralizationin vitro. Taken together, Alg-CMC has been illustrated to be suitable to print scaffolds with dental epithelial cells for enamel tissue regeneration.

[Clinical application of a self-developed mouth opener with a tongue base retractor in the operation of deep part of tongue base].

Objective:To test the application effect of a self-developed mouth opener with a tongue base retractor in the operation of the deep part of tongue base. Methods:The tongue base surgical field was exposed by using a self-developed mouth opener with a tongue base retractor in 8 patients who underwent deep tongue base operation via oral approach, the difficulty of operation, the effect of exposure of operation field, the tear of mucous membrane of the pharynx arch and the risk of tongue paralysis were observed. Results:The self-made mouth opener can expose the deep operative field of the tongue root by using the self-provided tongue root retractor during the operation, and the operation is conducted under the guidance of angle endoscope. The operative field of 8 patients was well exposed during the whole operation, there was no pharyngeal mucosa tearing and postoperative tongue paralysis. Conclusion:The self-made mouth opener has the advantages of simple operation, good exposure effect and less complications, but it needs rigid bending instruments in some operations.

Entecavir combined with interferon-α Is superior to entecavir monotherapy in reducing hepatic and extrahepatic cancer in patients with chronic hepatitis B.

BACKGROUND: The objective of this study was to assess whether entecavir (ETV) in combination with interferon-α (IFN-α) could reduce hepatocellular cancer (HCC) and extrahepatic cancers (EHCs) in patients with chronic hepatitis B (CHB). METHODS: The cohort consisted of 4194 patients with CHB treated with ETV combined with IFN-α or ETV monotherapy at a tertiary hospital in Beijing, China, from January 2009 to December 2017. The risks, hazard ratios (HRs), and 95% confidence intervals (CIs) of HCC and EHCs were compared in the 2 groups. RESULTS: In a multivariate Cox regression analysis, a significantly lower risk of HCC (HR, 0.6; 95% CI, 0.3-0.9; P = .0310) and a marginally significantly lower risk of EHCs (HR, 0.2; 95% CI, 0.02-1.3; P = .0854) were observed in the group receiving ETV combined with IFN-α in comparison with the ETV monotherapy group. The annual virological response rates were significantly higher in the combination therapy group versus the monotherapy group (33.8% vs 21.2%; P < .0001), but the hepatitis B surface antigen (HBsAg) seroclearance rates were not (1.2% vs 0.9%; P = .8537). The HRs were consistent with propensity score-based matching, inverse probability weighting adjustments, and adjustments for virological response and HBsAg seroclearance. CONCLUSIONS: ETV combined with IFN-α therapy is superior to ETV monotherapy in reducing the risk of HCC and EHCs for patients with CHB. People who can tolerate and benefit from IFN-α therapy could consider combination therapy.

Characterization of Tissue Scaffolds Using Synchrotron Radiation Microcomputed Tomography Imaging.

Distinguishing from other traditional imaging, synchrotron radiation microcomputed tomography (SR-µCT) imaging allows for the visualization of three-dimensional objects of interest in a nondestructive and/or in situ way with better spatial resolution, deep penetration, relatively fast speed, and/or high contrast. SR-µCT has been illustrated promising for visualizing and characterizing tissue scaffolds for repairing or replacing damaged tissue or organs in tissue engineering (TE), which is of particular advance for longitudinal monitoring and tracking the success of scaffolds once implanted in animal models and/or human patients. This article presents a comprehensive review on recent studies of characterization of scaffolds based on SR-µCT and takes scaffold architectural properties, mechanical properties, degradation, swelling and wettability, and biological properties as five separate sections to introduce SR-µCT wide applications. We also discuss and highlight the unique opportunities of SR-µCT in various TE applications; conclude this article with the suggested future research directions, including the prospective applications of SR-µCT, along with its challenges and methods for improvement in the field of TE.

[Free trajectory cone beam computed tomography reconstruction method for synchronous scanning of geometric calibration phantom and imaging object].

In order to suppress the geometrical artifacts caused by random jitter in ray source scanning, and to achieve flexible ray source scanning trajectory and meet the requirements of task-driven scanning imaging, a method of free trajectory cone-beam computed tomography (CBCT) reconstruction is proposed in this paper. This method proposed a geometric calibration method of two-dimensional plane. Based on this method, the geometric calibration phantom and the imaging object could be simultaneously imaged. Then, the geometric parameters could be obtained by online calibration method, and then combined with the geometric parameters, the alternating direction multiplier method (ADMM) was used for image iterative reconstruction. Experimental results showed that this method obtained high quality reconstruction image with high contrast and clear feature edge. The root mean square errors (RMSE) of the simulation results were rather small, and the structural similarity (SSIM) values were all above 0.99. The experimental results showed that it had lower image information entropy (IE) and higher contrast noise ratio (CNR). This method provides some practical value for CBCT to realize trajectory freedom and obtain high quality reconstructed image.

Virologic response maintenance and hepatocellular carcinoma in chronic hepatitis B patients treated with entecavir.

INTRODUCTION: The treatment evidence for entecavir-treated chronic hepatitis B (CHB) patients without maintaining of virologic response (MVR, defined as persistent HBV DNA <20 IU/mL during therapy) remains uncertain. We aimed to determine the relationship between non-MVR and hepatocellular carcinoma (HCC) risk in entecavir-treated CHB patients. METHODS: A cohort of 1447 entecavir-treated CHB patients were enrolled. Multivariate and propensity score-based inverse probability weighting (IPW) model was performed to estimate the effect of MVR on HCC. RESULTS: During a median follow-up of 5 years, 214 (14.8%) patients occurred with non-MVR. Non-MVR patients had a higher risk of HCC [the IPW model: hazard ratio (HR) = 3.59, 95% confidence interval (CI): 2.23-5.75] than MVR patients, especially in those with cirrhosis (HR = 4.60, 95% CI: 2.81-7.56) and the high HCC score by the Chinese University of Hong Kong (HR = 4.35, 95% CI: 2.58-7.32). MVR patients with transient (HR = 4.72, 95% CI: 1.98-11.24) or persistent (HR = 12.16, 95% CI: 3.58-41.31) abnormal ALT after virologic response had higher HCC hazard. CONCLUSIONS: Our study indicated an elevated HCC probability for entecavir-treated CHB patients with Non-MVR, especially for those with cirrhosis or a high predicted score at baseline. For MVR patients, the trajectories of ALT after virologic response suggested different HCC risks.

GapFill-Recon Net: A Cascade Network for simultaneously PET Gap Filling and Image Reconstruction.

PET image reconstruction from incomplete data, such as the gap between adjacent detector blocks generally introduces partial projection data loss, is an important and challenging problem in medical imaging. This work proposes an efficient convolutional neural network (CNN) framework, called GapFill-Recon Net, that jointly reconstructs PET images and their associated sinogram data. GapFill-Recon Net including two blocks: the Gap-Filling block first address the sinogram gap and the Image-Recon block maps the filled sinogram onto the final image directly. A total of 43,660 pairs of synthetic 2D PET sinograms with gaps and images generated from the MOBY phantom are utilized for network training, testing and validation. Whole-body mouse Monte Carlo (MC) simulated data are also used for evaluation. The experimental results show that the reconstructed image quality of GapFill-Recon Net outperforms filtered back-projection (FBP) and maximum likelihood expectation maximization (MLEM) in terms of the structural similarity index metric (SSIM), relative root mean squared error (rRMSE), and peak signal-to-noise ratio (PSNR). Moreover, the reconstruction speed is equivalent to that of FBP and was nearly 83 times faster than that of MLEM. In conclusion, compared with the traditional reconstruction algorithm, GapFill-Recon Net achieves relatively optimal performance in image quality and reconstruction speed, which effectively achieves a balance between efficiency and performance.

A programmable polymer library that enables the construction of stimuli-responsive nanocarriers containing logic gates.

Stimuli-responsive biomaterials that contain logic gates hold great potential for detecting and responding to pathological markers as part of clinical therapies. However, a major barrier is the lack of a generalized system that can be used to easily assemble different ligand-responsive units to form programmable nanodevices for advanced biocomputation. Here we develop a programmable polymer library by including responsive units in building blocks with similar structure and reactivity. Using these polymers, we have developed a series of smart nanocarriers with hierarchical structures containing logic gates linked to self-immolative motifs. Designed with disease biomarkers as inputs, our logic devices showed site-specific release of multiple therapeutics (including kinase inhibitors, drugs and short interfering RNA) in vitro and in vivo. We expect that this 'plug and play' platform will be expanded towards smart biomaterial engineering for therapeutic delivery, precision medicine, tissue engineering and stem cell therapy.

Patch Based Grid Artifact Suppressing in Digital Mammography.

The mammography is the first choice of breast cancer screening, which has proven to be the most effective screening method. An antiscatter grid is usually employed to enhance the contrast of image by absorbing unexpected scattered signals. However, the grid pattern casts shadows and grid artifacts, which severely degrade the image quality. To solve the problem, we propose the patch based frequency signal filtering for fast grid artifacts suppressing. As opposed to whole image processing synchronously, the proposed method divides image into a number of blocks for tuning filter simultaneously, which reduces the frequency interference among image blocks and saves computation time by multithread processing. Moreover, for mitigating grid artifacts more precisely, characteristic peak detection is employed in each block automatically, which can accurately identify the location of the antiscatter grid and its motion pattern. Qualitative and quantitative studies were performed on simulation and real machine data to validate the proposed method. The results show great potential for fast suppressing grid artifacts and generating high quality of digital mammography.

Recent advances in siRNA delivery for cancer therapy using smart nanocarriers.

Small interfering RNAs (siRNAs) can selectively target and downregulate disease-causing genes, holding great promise in treating human diseases, especially malignant cancers. However, how to efficiently deliver siRNAs into target cell cytosol is a problem that has hindered their clinical application. Here, we review the recent strategies for siRNA delivery on the basis of smart nanocarriers by using stimuli-responsive materials. We highlight the rationales of how to design smart nanocarriers responsive to physiological and external stimuli to improve the delivery efficiency, targeting precision and gene silencing efficacy. Finally, we provide an outlook on the fundamental limitation for clinical translation of siRNA-based nanomedicine that should be overcome by the combination of chemistry, biology, material and medical science.

On-chip Si-based Bragg cladding waveguide with high index contrast bilayers.

A new silicon based waveguide with full CMOS compatibility is developed to fabricate an on-chip Bragg cladding waveguide that has an oxide core surrounded by a high index contrast cladding layers. The cladding consists of several dielectric bilayers, where each bilayer consists of a high index-contrast pair of layers of Si and Si3N4. This new waveguide guides light based on omnidirectional reflection, reflecting light at any angle or polarization back into the core. Its fabrication is fully compatible with current microelectronics processes. In principle, a core of any low-index material can be realized with our novel structure, including air. Potential applications include tight turning radii, high power transmission, and dispersion compensation.