Glucose oxidase (GOD), a popular enzyme used in pharmaceutical, food, bio-sensor and other fields, can well catalyze the oxidation of glucose to produce gluconic acid and hydrogen peroxide. The main limitation for the applications of free enzyme is its less preferable owing to its weaker activity against to changeable conditions such as pH, temperature, and organic solvent. The immobilization is thought to be an effective way to improve the stability of GOD under harsh conditions. In this study, MIL-125 was applied as a fixing carrier to anchor GOD for the first time. The synthesized MIL-125 was characterized by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption and DFT pore size distribution. The FT-IR spectra were employed to study the structural stability and interface interaction of MIL-125 with GOD. Compared to the previously reported GOD-related adsorption results, the higher adsorption capacity of GOD was obtained on MIL-125. The adsorption kinetics and isotherm analyses indicated that the adsorption process of GOD on MIL-125 was a spontaneous endothermic process, which was more in line with the pseudo-second-order kinetic model. The enzyme activity assay showed that the values of Km and Vmax for immobilized GOD on MIL-125 were 14.482 mmol L−1 and 0.356 mmol⋅L−1⋅min−1, respectively, which were lower than those of free GOD. But, compared to free GOD, the immobilized GOD showed less sensitivity to the changes in temperature, pH values and organic solvent. After six cyclic catalytic reactions, the immobilized GOD remained over 43.79% of its initial activity. The endurability tests showed that the immobilized GOD showed 43.41% of its initial activity after storage for 21 days at room temperature; meanwhile, the free GOD almost lost its initial activity at the end of 3 days under the same condition. The results demonstrated that the MOF-immobilized enzymes were more stable and had a broader potential application in the enzyme immobilization engineering.

The halloysite clay nanotube lumen has shown great application potential in the field of environmental remediation. This relies on delicate manipulation of the clay nanotube lumen and benefits from the unique functionality of the nanotube lumen.

In this study, FeMg-LDH loaded with bentonite (FeMg-LDH@bentonite) was prepared using the facile coprecipitating method in situ to remove heavy metals from water and then characterized using XRD, SEM, TEM, FTIR, BET, TGA, and XPS. Pb (II) and Cd (II) were selected as the representative heavy metals to evaluate the adsorption capability of the FeMg-LDH@bentonite. The batch adsorption method was adopted to test the effects of the contact time, pH, initial concentration, different cations, and temperatures. The kinetic study indicated that the adsorption of heavy metals onto FeMg-LDH@bentonite was well fitted by the pseudo-second-order method. Isotherms were effectively simulated based on the Langmuir model. The maximal adsorption capability of Cd (II) and Pb (II) can reach 510.2 mg/g and 1397.62 mg/g, exceeding those of conventional adsorbents. The adsorption mechanisms of FeMg-LDH@bentonite demonstrating that there may exist surface complexation, ion exchange, and chemical deposition between FeMgLDH@bentonite and heavy metals. Moreover, FeMg-LDH@bentonite was found to have a promising application for practically treating wastewater with heavy metals and can be used for various environmental water pollution treatments. The material may be used for heavy metal contaminated soil in the future. (c) 2021 Elsevier Inc. All rights reserved.

Layered double hydroxides (LDHs) are ionic laminar composites composed of positively charged brucite-like layers with an interlayered region containing charged compensating anions and solvation molecules. Such functional LDHs materials present a strong potential for heavy metal treatment especially for wastewater and soil, due to the large surface area and layered structure. This paper started with the background of techniques for heavy metals treatment and then discussed the potential environmental toxic effects, feasibility, stability of LDH composites. The preparation strategies of LDHs composites, and their application were summarized, followed by main mechanisms involving chelation, complexation, surface precipitation, ion exchange. This work also presented the potential environmental toxic effects, feasibility, stability of LDHs composites, reuse of waste liquid and the ratio adjustment of M2+ and N3+ for LDHs synthesis. While most efforts focused on improving the absorption capacity of LDHs by composites construction, ignoring the toxicity effects and detailed mechanism investigation. Based on a thorough review of the latest development, the challenges and perspectives would be proposed, offering promising insights on environmental purification via LDHs based materials.

Polymer photosensitizers (PPSs) with the distinctive properties of good light-harvesting capability, high photostability, and excellent tumor retention effects have aroused great research interest in photodynamic therapy (PDT). However, their potential translation into clinic was often constrained by the hypoxic nature of tumor microenvironment, the aggregation-caused reduced production of reactive oxygen species (ROS), and the tedious procedure of manufacture. As a powerful and versatile strategy, vacancy engineering possesses the unique capability to effectively improve the photogenerated electron efficiency of nanomaterials for high-performance O2 and ROS production. Herein, by introducing vacancy engineering into the design of PPSs for PDT for the first time, we synthesized a novel PPS of Au-decorated polythionine (PTh) nanoconstructs (PTh@Au NCs) with the unique integrated features of distinguished O2 self-evolving function and highly efficient ROS generation for achieving the greatly enhanced PDT efficacy toward hypoxic tumor both in vitro and in vivo. The incorporation of Au into PTh leads to the special PTh-Au heterostructure-induced sulfur vacancies in PTh@Au NCs, which results in an efficient electron-hole separation performance and also plays a key role in a long lifetime of free electrons and holes. Accordingly, an ∼2- to 3-fold ROS generation and an ∼1.5-fold increase of O2 self-supply than the pure PTh nanoparticles (NPs) were obtained even under hypoxic conditions upon exposure to 650 nm light. By combining such superior ROS generation and O2 self-supply performances with the outstanding cellular internalization and tumor accumulation capacities, an advanced antitumor effect with the achievement of almost complete hypoxic tumor elimination in vivo or 88% cell destruction in vitro was acquired by the PTh@Au NCs. In addition, the distinctive facile one-step redox strategy for PTh@Au NCs synthesis compared to the reported PPSs for PDT also makes it beneficial for potential practical application. The first introduction of vacancy engineering concept into PPSs in the field of PDT proposed in this work offers a new strategy for the development and design highly efficient PPSs for PDT applications.

In this paper, we present results from our theoretical and experimental exploration of tailoring the absorption spectrum of a type of metamaterial absorber through manipulating the symmetricity and uniformity of the metallic submicron particle array on the top layer. The absorber under study is a metal-insulator-metal (MIM) trilayer structure made up of a top layer of engineered metallic submicron particles, a middle insulator spacer layer and an opaque ground metal reflector layer. We first studied the structure with a top layer consisting of a uniform array of raindrop-shaped gold (Au) submicron disks. We designed the raindrop shape with a reflectional symmetry on the 45° line. We compared the spectrum generated with that of a similar structure but the top layer which is filled with uniformly arranged circular submicron discs. It has been well reported that an array of circular particles each with both reflectional and rotational symmetries usually generates a spectrum with one absorption spike. By changing the circular shape to raindrop shape, the MIM absorber has been predicted to generate two absorption peaks with significantly broadened absorption bandwidth. Subsequently, we found that even wider spectra could be achieved if the top layer is built with a periodic arrangement of the unit cells containing differently sized raindrop-shaped disks. This leads to a wider bandwidth of higher than 50% absorbance ranging from 2.80 μm to 3.90 μm.

Developing low-cost, durable, and high-performance materials for the separation of water/oil mixtures (free oil/water mixtures and emulsions) is critical to wastewater treatment and resource recovery. However, this currently remains a challenge. In this work, we report a biopolymer microfiber assembly, fabricated from the recovery of tissue waste, as a low-cost and high-performance filter for oily wastewater treatment. The microfiber filters demonstrate superhydrophilicity (water contact angle of 28.8°) and underwater superoleophobicity (oil contact angle of 154.2°), and thus can achieve separation efficiencies of >96% for both free oil/water mixtures and surfactant-stabilized emulsions even in highly acidic (pH 2.2)/alkaline (pH 11.8) conditions. Additionally, the prepared microfiber filters possess a much higher resistance to oil fouling than conventional membranes when filtering emulsions, which is because the large-sized 3D interconnected channels of the filters can delay the formation of a low-porosity oil gel layer on their surface. The filters are expected to practically apply for the oily wastewater treatment and reduce the amount of tissue waste entering the environment.

In this work, a terahertz metamaterial absorber with five absorption bands that can be used in the areas of sensing, imaging, and detecting is investigated. The absorber structure contains four quarter-sectional circular rings and a cross in a square ring layer, a dielectric layer, and ground metal layer. Simulation results display that the absorber with such configuration possesses five distinct high absorption peaks at 0.7, 1.6, 2.32, 2.63, and 3.15 THz and show polarization-insensitive property due to its 4-fold symmetric property. The physical origins of the absorber characteristics are attributed to dipolar and hexapolar resonances of the patterned metallic arrays on the top layer, as established by analyzing the electrical field density. In addition to, structural parameters' influences on the absorption bands are also studied and the results indicate that total absorption bands and coefficients can be effectively altered by changing the structural parameters and configurations, which is beneficial for its practical applications.

The aim of this study is the utilization of human medical CT images to quantitatively evaluate two sorts of "error-driven" material algorithms, that is, the isotropic and orthotropic algorithms, for bone remodelling. The bone remodelling simulations were implemented by a combination of the finite element (FE) method and the material algorithms, in which the bone material properties and element axes are determined by both loading amplitudes and daily cycles with different weight factor. The simulation results showed that both algorithms produced realistic distribution in bone amount, when compared with the standard from CT data. Moreover, the simulated L-T ratios (the ratio of longitude modulus to transverse modulus) by the orthotropic algorithm were close to the reported results. This study suggests a role for "error-driven" algorithm in bone material prediction in abnormal mechanical environment and holds promise for optimizing implant design as well as developing countermeasures against bone loss due to weightlessness. Furthermore, the quantified methods used in this study can enhance bone remodelling model by optimizing model parameters to gap the discrepancy between the simulation and real data.

Objective: X-ray luminescence computed tomography (XLCT) is an emerging and promising modality, but suffers from inferior reconstructions and smoothed target shapes. This work aims to improve the image quality with new mathematical framework. Methods: We present a Bayesian local regularization framework to tackle the ill-conditioness of XLCT. Different from traditional overall regularization strategies, the proposed method utilizes correlations of neighboring voxels to regularize the solution locally based on generalized adaptive Gaussian Markov random field (GAGMRF), and provides an adjustable parameter to facilitate the edge-preserving property. Results: Numerical simulations and phantom experiments show that the GAGMRF method yields both high image quality and accurate target shapes. Conclusion: Compared to conventional L2 and L1 regularizations, GAGMRF provides a new and efficient model for high quality imaging based on the Bayesian framework. Significance: The GAGMRF method offers a flexible regularization framework to adapt to a wide range of biomedical applications.

The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT.

目的 荧光共振能量转移(fluorescent resonance energy transfer,FRET)探针由于自身仍存在诸多局限,其在活体成像领域尚未得到广泛应用.本文旨在解决FRET探针在活体定量分子影像应用中所存在的瓶颈问题,即如何利用FRET探针精准计算目标物浓度,以及如何基于FRET探针实现三维成像.方法 基于探针和目标物结合时的化学反应平衡关系,提出一种新型分析方法,以精确定量待测物[钙调素(calmodulin,CaM)]的浓度.同时对于FRET探针的活体分子成像,结合荧光透射成像(3D-FMT)方法,建立了可进行三维时空动态FRET检测的平台系统,对FRET探针的测量结果(即待测物浓度)进行实时定量的三维重建.结果 准确地定量了待测物CaM浓度,并得到了高质量的3D-FRET分布影像.结论 提出FRET探针在活体成像应用领域两个关键问题的解决方案,为基因编码FRET探针向活体分子影像领域的推广奠定了重要的技术基础.

Traditional spectral imaging systems mainly rely on spatial scanning or spectral scanning methods to acquire spatial and spectral features. The acquisition is time-consuming and cannot fully satisfy the need of monitoring dynamic phenomenon and observing different structures of the specimen simultaneously. To overcome these barriers, we develop a video-rate simultaneous multispectral imaging system built with a spectral multiplexed volume holographic grating (VHG) and few optical components. Four spectral multiplexed volume holograms optimized for four discrete spectral bands (centered at 488 nm, 530 nm, 590 nm and 620 nm) are recorded into an 8x12 mm photo-thermal refractive glass. The diffraction efficiencies of all the holograms within the multiplexed VHG are greater than 80%. With the high throughout multiplexed VHG, the system can work with both reflection and fluorescence modes and allow simultaneous acquisition of spectral and spatial information with a single exposure. Imaging experiments demonstrate that the multispectral images of the target illuminated with white light source can be obtained. Fluorescence images of multiple fluorescence objects (two glass beads filled with 20 uL 1.0 mg/mL quantum dots solutions that emit 530 +/- 15 nm and 620 +/- 15 nm fluorescence, respectively) buried 3 mm below the surface of a tissue mimicking phantom are acquired. The results demonstrate that the system can provide complementary information in fluorescence imaging. The design diagram of the proposed system is given to explain the advantage of compactness and flexibility in integrating with other imaging platforms.

BACKGROUND:Fluorescence molecular tomography (FMT) is an optical imaging technique that reveals biological processes within small animals through non-invasively reconstructing the distributions of fluorescent agents. The primary problem in FMT with non-stationary fluorescent yield is the increase of the unknown parameters to be reconstructed. In this paper, a method is proposed to reconstruct dynamic fluorescent yield.METHODS:A shape-based reconstruction method that recovers dynamic fluorescent yield with a level set method is proposed for FMT. To reduce the number of unknown parameters, a level set function is introduced to describe the shape of target and a small number of parameters are used to describe the fluorescent yields at different time points.RESULTS:Results of simulations and phantom experiments demonstrate that the proposed method can recover well the dynamic fluorescent yields, shapes and locations of the target.CONCLUSIONS:The proposed method can handle the cases with non-stationary fluorescent yields and recover the fluorescent yields at each projection angle.

Fluorescence molecular tomography (FMT) can visualize biological activities at cellular and molecular levels in vivo, and has been extensively used in drug delivery and tumor detection research of small animals. The ill-posedness of the FMT inverse problem makes it difficult to reconstruct and resolve multiple adjacent fluorescent targets that have different functional features but are labeled with the same fluorochrome. An algorithm based on independent component analysis (ICA) for multispectral excited FMT is proposed to resolve multiple fluorescent targets in this study. Fluorescent targets are excited by multispectral excitation, and the three-dimensional distribution of fluorescent yields under the excitation spectrum is reconstructed by an iterative Tikhonov regularization algorithm. Subsequently, multiple fluorescent targets are resolved from mixed fluorescence signals by employing ICA. Simulations were performed and the results demonstrate that multiple adjacent fluorescent targets can be resolved if the number of excitation wavelengths is not smaller than that of fluorescent targets with different concentrations. The algorithm obtains both independent components that provide spatial information of different fluorescent targets and spectral courses that reflect variation trends of fluorescent yields along with the excitation spectrum. By using this method, it is possible to visualize the metabolism status of drugs in different structure organs, and quantitatively depict the variation trends of fluorescent yields of each functional organ under the excitation spectrum. This method may provide a pattern for tumor detection, drug delivery and treatment monitoring in vivo.

As a newly developed medical model based on bioinformatics, molecular medicine, clinical diagnostics and medical imaging, precision medicine makes use of advanced technology to accurately trace causes of diseases and thusdetermine therapeutic regimen for different patients. The ultimate aim of precision medicine is to facilitate the diagnosis capability, medical treatment capability, and nursing effect in all medical-related ifelds, and to ifnally realize personalized medicine. Fluorescence molecular imaging is an essential technology involved in the realization of precision medicine. It provides in vivo functional information as well as imaging in cellular and molecular levels, which differs from traditional structural imaging. Based on recent development of related research both at home and abroad, this paper summarizes the reconstruction algorithms and imaging systems for lfuorescence molecular imaging and describes the value and future of the application with precision medicine as background.

X-ray luminescence computed tomography (XLCT), which aims to achieve molecular and functional imaging by X-rays, has recently been proposed as a new imaging modality. Combining the principles of X-ray excitation of luminescence-based probes and optical signal detection, XLCT naturally fuses functional and anatomical images and provides complementary information for a wide range of applications in biomedical research. In order to improve the data acquisition efficiency of previously developed narrow-beam XLCT, a cone beam XLCT (CB-XLCT) mode is adopted here to take advantage of the useful geometric features of cone beam excitation. Practically, a major hurdle in using cone beam X-ray for XLCT is that the inverse problem here is seriously ill-conditioned, hindering us to achieve good image quality. In this paper, we propose a novel Bayesian method to tackle the bottleneck in CB-XLCT reconstruction. The method utilizes a local regularization strategy based on Gaussian Markov random field to mitigate the ill-conditioness of CB-XLCT. An alternating optimization scheme is then used to automatically calculate all the unknown hyperparameters while an iterative coordinate descent algorithm is adopted to reconstruct the image with a voxel-based closed-form solution. Results of numerical simulations and mouse experiments show that the self-adaptive Bayesian method significantly improves the CB-XLCT image quality as compared with conventional methods.

Goal: High-intensity background fluorescence is generally encountered in fluorescence molecular tomography (FMT), because of the accumulation of fluorescent probes in nontarget tissues or the existence of autofluorescence in biological tissues. The reconstruction results are affected or even distorted by the background fluorescence, especially when the distribution of fluorescent targets is relatively sparse. The purpose of this paper is to reduce the negative effect of background fluorescence on FMT reconstruction. Methods: After each iteration of the Tikhonov regularization algorithm, 3-D discrete cosine transform is adopted to filter the intermediate results. And then, a sparsity constraint step based on L1 regularization is applied to restrain the energy of the objective function. Results: Phantom experiments with different fluorescence intensities of homogeneous and heterogeneous background are carried out to validate the performance of the proposed scheme. The results show that the reconstruction quality can be improved with the proposed iterative correction scheme. Conclusion and Significance: The influence of background fluorescence in FMT can be reduced effectively because of the filtering of the intermediate results, the detail preservation, and noise suppression of L1 regularization.

Covalently conjugating proteins with synthetic polymers, particularly poly(ethylene glycol) (PEG) is widely used as a means to improve protein solubility and stability, prolong their circulating half-lives, and lower their immunogenicity. Conventionally, these polymers are attached to random locations on the protein surfaces through the modification of the reactive side chains of amino acid residues such as lysine and cysteine. The “grafting to” polymer conjugation usually leads to heterogeneous products with reduced activity and low yield, which may not be compatible with the intended applications. Therefore, it is highly desirable to synthesize well-defined protein–polymer conjugates by site-specific polymer conjugation. Recently, in situ growth of polymer conjugates from proteins (“grafting from”) has emerged as an alternative to the “grafting to” method. Particularly, site-specific in situ growth of polymer bioconjugates (SIP) is promising in overcoming the limitations of the “grafting to” method. In this review, we introduce the chemistry for synthesis of well-defined protein–polymer conjugates, and emphasize the SIP method as the next-generation platform for synthesis of well-defined protein–polymer conjugates. Furthermore, we exemplify biomedical applications of well-defined protein–polymer conjugates. In the end, we come up potential directions in this research field.