Bioconjugation of nanozyme and natural enzyme to enable a one-step cascade reaction for the detection of metabolites.

Nanozyme, with enzyme-mimicking activity and excellent stability, has attracted extensive attention. However, some inherent disadvantages, including poor dispersion, low selectivity, and insufficient peroxidase-like activity, still limit its further development. Therefore, an innovative bioconjugation of a nanozyme and natural enzyme was conducted. In the presence of graphene oxide (GO), histidine magnetic nanoparticles (H-Fe3O4) were first synthesized by a solvothermal method. The GO-supported H-Fe3O4 (GO@H-Fe3O4) exhibited superior dispersity and biocompatibility because GO was the carrier and possessed outstanding peroxidase-like activity because of the introduction of histidine. Furthermore, the mechanism of the peroxidase-like activity of GO@H-Fe3O4 was the generation of •OH. Uric acid oxidase (UAO) was selected as the model natural enzyme and covalently linked to GO@H-Fe3O4 with hydrophilic poly(ethylene glycol) as a linker. UAO could specifically catalyze the oxidation of uric acid (UA) to generate H2O2, and subsequently, the newly produced H2O2 oxidized the colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue ox-TMB under the catalysis of GO@H-Fe3O4. Based on the above cascade reaction, the GO@H-Fe3O4-linked UAO (GHFU) and GO@H-Fe3O4-linked ChOx (GHFC) were used for the detection of UA in serum samples and cholesterol (CS) in milk, respectively. The method based on GHFU exhibited a wide detection range (5-800 µM) and a low detection limit (1.5 µM) for UA, and the method based on GHFC exhibited a wide detection range (4-400 µM) and a low detection limit (1.13 µM) for CS. These results demonstrated that the proposed strategy had great potential in the field of clinical detection and food safety.

Anastomotic leak risk factors following colon cancer resection: a systematic review and meta-analysis.

BACKGROUND: Despite improved surgical techniques, anastomotic leakage is still a serious complication that can occur after colon cancer resection, resulting in increased morbidity and mortality. The aim of this study was to evaluate the risk factors for anastomotic leakage after colon cancer surgery, provide a theoretical basis for reducing its occurrence, and guide the practice of clinicians. METHODS: A systematic review of PubMed, Ovid, Web of Science and Cochrane Central Register of Controlled Trials databases was conducted by using a combination of subject terms and free words for online searches. The databases were searched from their inception to 31 March 2022, and all cross-sectional, cohort or case‒control studies examining the risk factors for the development of anastomotic fistula after surgery for colon cancer were identified. RESULT: A total of 2133 articles were searched for this study, and 16 publications were ultimately included, all of which were cohort studies. A total of 115,462 subjects were included, and a total of 3959 cases of anastomotic leakage occurred postoperatively, with an incidence of 3.4%. The odds ratio (OR) and 95% confidence interval (CI) were used for evaluation. Male sex (OR = 1.37, 95% CI: 1.29-1.46, P < 0.00001), BMI (OR = 1.04, 95% CI: 1.00-1.08, P = 0.03), diabetes (OR = 2.80, 95% CI: 1.81-4.33, P < 0.00001), combined lung disease (OR = 1.28, 95% CI: 1.15-1.42, P < 0.00001), anaesthesia ASA score (OR = 1.35, 95% CI: 1.24-1.46, P < 0.00001), ASA class ≥ III (OR = 1.34, 95% CI: 1.22-1.47, P < 0.00001), emergency surgery (OR = 1.31, 95% CI: 1.11-1.55, P = 0.001), open surgery (OR = 1.94, 95% CI: 1.69-2.24, P < 0.00001) and type of surgical resection (OR = 1.34, 95% CI: 1.12-1.61, P = 0.002) are risk factors for anastomotic leakage after colon cancer surgery. There is still a lack of strong evidence on whether age (OR = 1.00, 95% CI: 0.99-1.01, P = 0.36) and cardiovascular disease (OR = 1.18, 95% CI: 0.94-1.47, P = 0.16) are factors influencing the occurrence of anastomotic leakage after colon cancer surgery. CONCLUSIONS: Male sex, BMI, obesity, coexisting pulmonary disease, anaesthesia ASA score, emergency surgery, open surgery and type of resection were risk factors for anastomotic leakage after colon cancer surgery. The effect of age and cardiovascular disease on postoperative anastomotic leakage in patients with colon cancer needs further study.

Construction of PEGylated boronate-affinity-oriented imprinting magnetic nanoparticles for ultrasensitive detection of ellagic acid from beverages.

Molecularly imprinted polymers (MIPs) can exhibit antibody-level affinity for target molecules. However, the nonspecific adsorption of non-imprinted regions for non-target molecules limits the application range of MIPs. Herein, we fabricated PEGylated boronate-affinity-oriented ellagic acid-imprinting magnetic nanoparticles (PBEMN), which first integrated boronate-affinity-oriented surface imprinting and sequential PEGylation for small molecule-imprinted MIPs. The resultant PBEMN possess higher adsorption capacity and faster adsorption rate for template ellagic acid (EA) molecules than the non-PEGylated control. To prove the excellent performance, the PBEMN were linked with hydrophilic boronic acid-modified/fluorescein isothiocyanate-loaded graphene oxide (BFGO), because BFGO could selectively label cis-diol-containing substances by boronate-affinity and output ultrasensitive fluorescent signals. Based on a dual boronate-affinity synergy, the PBEMN first selectively captured EA molecules by boronate-affinity-oriented molecular imprinted recognition, and then the EA molecules were further labeled with BFGO through boronate-affinity. The PBEMN linked BFGO (PBPF) strategy provided ultrahigh sensitivity for EA molecules with a limit of detection of 39.1 fg mL-1, resulting from the low nonspecific adsorption of PBEMN and the ultrasensitive fluorescence signal of BFGO. Lastly, the PBPF strategy was successfully employed in the determination of EA concentration in a spiked beverage sample with recovery and relative standard deviation in the range of 96.5 to 104.2% and 3.8 to 5.1%, respectively. This work demonstrates that the integration of boronate-affinity-oriented surface imprinting and sequential PEGylation may be a universal tool for improving the performance of MIPs.

Synthesis of multirecognition magnetic molecularly imprinted polymer by atom transfer radical polymerization and its application in magnetic solid-phase extraction.

In this work, we reported an effective method for the synthesis of a multirecognition magnetic molecularly imprinted polymer (MMIP) with atom transfer radical polymerization (ATRP), using 2,4-diamino-6-methyl-1,3,5-triazine as pseudo-template. The resulting MMIP was characterized in detail by Fourier transform-infrared (FT-IR) spectra, scanning electron microscopy (SEM), thermogravimetic analysis (TGA), and vibrating sample magnetometry (VSM). These results indicated the successful synthesis of MMIP with sufficient thermal stability and magnetic properties. The adsorption experiments were carried out to evaluate the specific selectivity of MMIP related to the spatial structure of target molecules. The MMIP exhibited multirecognition ability and excellent binding capability for melamine (MEL), cyromazine (CYR), triamterene (TAT), diaveridine (DVD), and trimethoprim (TME), and the apparent maximum number of binding sites (Q max) was 77.5, 75.2, 72.5, 69.9, and 70.4 µmol g-1, respectively. The multirecognition MMIP not only possessed adequate magnetic responsiveness for fast separation but also avoided the risk of template leakage on trace component analysis. Therefore, it was suitable for serving as a magnetic solid-phase extraction (MSPE) adsorbent. MSPE coupled with high-performance liquid chromatography analysis was applied to enrich and separate five target molecules from three samples. Recoveries for all target molecules ranged from 81.6 to 91.5% with relative standard deviations of no more than 4.1% (n = 3). Graphical abstract Multirecognition property of magnetic molecularly imprinted polymer prepared with pseudo template.

Enhancement of selective separation on molecularly imprinted monolith by molecular crowding agent.

In this study, a new molecularly imprinted polymer chiral stationary phase (MIP-CSP) was prepared utilizing molecular crowding agent for improvement the selective separation ability. S-amlodipine (S-AML), methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA), and polymethyl methacrylate (PMMA) were selected as template, functional monomer, cross-linker, and molecular crowding agent, respectively. The composition of formulas for MIP-CSP was optimized, and the permeability and structural feature of resultant MIP-CSP were characterized. The effect of mobile-phase composition, including ionic strength, pH, and organic modifier content, was investigated for achieving the selective separation of rac-amlodipine (rac-AML) on MIP-CSP. The baseline separation of rac-AML was achieved with resolution of 1.58, whereas no selective separation was observed on the imprinted monolith without molecular crowding agent. The perturbation chromatography method was successfully applied to evaluate the recognition mechanism of templates on MIP-CSP. The retention time of S-AML detected in typical analytical conditions was obviously greater than the time of negative peak derived from perturbation, which indicated the retention of template may be due to the imprinted cavities on MIP-CSP. Additionally, the result of Van't Hoff analysis indicated that the chiral separation of rac-AML on MIP-CSP was an entropy-driven process, which supported the molecular imprinting theory. These results reveal that molecular crowding is a potential strategy for preparation of MIP-CSP with excellent selective separation ability. Graphical Abstract Improvement of chiral separation on molecularly imprinted monolith by molecular crowding condition.

[Correction Method of Atmospheric Scattering Effect Based on Three Spectrum Bands].

As a major error of CO2 retrieval, atmospheric scattering effect hampers the application of satellite products. Effect of aerosol and combined effect of aerosol and ground surface are important source of atmospheric scattering, so it needs comprehensive consideration of scattering effect from aerosol and ground surface. Based on the continuum, strong and weak absorption part of three spectrum bands O2-A, CO2 1.6 µm and 2.06 µm, information of aerosol and albedo was analyzed, and improved full physics retrieval method was proposed, which can retrieve aerosol and albedo simultaneously to correct the scattering effect. Simulation study on CO2 error caused by aerosol and ground surface albedo CO2 error by correction method was carried out. CO2 error caused by aerosol optical depth and ground surface albedo can reach up to 8%, and CO2 error caused by different types of aerosol can reach up to 10%, while these two types of error can be controlled within 1% and 2% separately by this correction method, which shows that the method can correct the scattering effect effectively. Through evaluation of the results, the potential of this method for high precision satellite data retrieval is obvious, meanwhile, some problems which need to be noticed in real application were also pointed out.

[Errors Analysis and Correction in Atmospheric Methane Retrieval Based on Greenhouse Gases Observing Satellite Data].

High precision retrieval of atmospheric CH4 is influenced by a variety of factors. The uncertainties of ground properties and atmospheric conditions are important factors, such as surface reflectance, temperature profile, humidity profile and pressure profile. Surface reflectance is affected by many factors so that it is difficult to get the precise value. The uncertainty of surface reflectance will cause large error to retrieval result. The uncertainties of temperature profile, humidity profile and pressure profile are also important sources of retrieval error and they will cause unavoidable systematic error. This error is hard to eliminate only using CH4 band. In this paper, ratio spectrometry method and CO2 band correction method are proposed to reduce the error caused by these factors. Ratio spectrometry method can decrease the effect of surface reflectance in CH4 retrieval by converting absolute radiance spectrometry into ratio spectrometry. CO2 band correction method converts column amounts of CH4 into column averaged mixing ratio by using CO2 1.61 µm band and it can correct the systematic error caused by temperature profile, humidity profile and pressure profile. The combination of these two correction methods will decrease the effect caused by surface reflectance, temperature profile, humidity profile and pressure profile at the same time and reduce the retrieval error. GOSAT data were used to retrieve atmospheric CH4 to test and validate the two correction methods. The results showed that CH4 column averaged mixing ratio retrieved after correction was close to GOSAT Level2 product and the retrieval precision was up to -0.24%. The studies suggest that the error of CH4 retrieval caused by the uncertainties of ground properties and atmospheric conditions can be significantly reduced and the retrieval precision can be highly improved by using ratio spectrometry method and CO2 hand correction method.

Comparison of multi-recognition molecularly imprinted polymers for recognition of melamine, cyromazine, triamterene, and trimethoprim.

Three fragmental templates, including 2,4-diamino-6-methyl-1,3,5-triazine (DMT), cyromazine (CYR), and trimethoprim (TME), were used to prepare the fragment molecularly imprinted polymers (FMIPs), respectively, in polar ternary porogen which was composed of ionic liquid ([BMIM]BF4), methanol, and water. The morphology, specific surface areas, and selectivity of the obtained FMIPs for fragmental analogues were systematically characterized. The experimental results showed that the FMIPs possessed the best specific recognition ability to the relative template and the greatest imprinting factor (IF) was 5.25, 6.69, and 7.11 of DMT on DMT-MIPs, CYR on CYR-MIPs, and TME on TME-MIPs, respectively. In addition, DMT-MIPs also showed excellent recognition capability for fragmental analogues including CYR, melamine (MEL), triamterene (TAT), and TME, and the IFs were 2.08, 3.89, 2.18, and 2.60, respectively. The effects of pH and temperature on the retention of the fragmental and structural analogues were studied in detail. Van't Hoff analysis indicated that the retention and selectivity on FMIPs were an entropy-driven process, i.e., steric interaction. The resulting DMT-MIPs were used as a solid-phase extraction material to enrich CYR, MEL, TAT, and TME in different bio-matrix samples for high-performance liquid chromatography analysis. The developed method had acceptable recoveries (86.8-98.6%, n = 3) and precision (2.7-4.6%) at three spiked levels (0.05-0.5 µg g(-1)).

Correlations between drug resistance of Beijing/W lineage clinical isolates of Mycobacterium tuberculosis and sublineages: a 2009-2013 prospective study in Xinjiang province, China.

BACKGROUND: The prevalence of drug-resistant tuberculosis (TB) in Xinjiang is higher than in other regions of China, and Beijing/W lineage Mycobacterium tuberculosis (MTB) is the dominant strain of MTB in Xinjiang. However, information on multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB, particularly the correlation between MDR and the Beijing/W lineage and the correlation between drug resistance and the Beijing/W sublineage strains, is limited. MATERIAL/METHODS: We conducted a prospective study to describe the prevalence of MDR/XDR TB, Beijing/W lineage and sublineage strains in Xinjiang in China from 2009 to 2013. All MTB underwent drug susceptibility testing to the first- and second-line anti-tuberculosis drugs. The Beijing/W lineages and sublineages were detected by large-sequence polymorphisms with polymerase chain reaction. RESULTS: A total of 410 clinical isolates were identified. The overall percentage of MDR and XDR cases in Xinjiang was 13.2% (54/410) and 13.0% (7/54), respectively. Overall, 9.8% (14/143) of the Beijing lineage MTB were MDR patients, and 15.6% (40/257) of the Non-Beijing lineage MTB were MDR patients. In the 143 Beijing MTB lineages, 11.2% isolates were in sublineage 105, 15.4% isolates were in sublineage 207, 69.2% isolates were in sublineage 181, and 4.2% isolates were in sublineage 150. None of the isolates were detected in sublineage 142. Significant differences between the Beijing/W and non-Beijing/W strains were observed regarding INH and EMB resistance, respectively. CONCLUSIONS: The prevalence of the MDR TB in Xinjiang remains high and imposes challenges for TB control. Four Beijing/W sublineage isolates were observed in Xinjiang. There was no correlation between MDR and the Beijing/W lineage and no correlation between drug resistance and the Beijing/W sublineage strains. Surveillance of the clinical isolates of MTB is recommended to strengthen the identification of MDR/XDR TB and sublineages of the Beijing/W strains.

[Mixed-Spectral Spatial Information Decomposition Model of Water Hyperspectral Inversion].

The effect of Mixed-hyperspectral in the water is difficult in quantitative remote sensing of water. Studies have shown that the only scalar spectrum information is difficult to solve the problem of complex mixed spectra of water. Besides the spectral information, spatial distribution of information is one of the obvious characteristics of the broad waters pollution, and can be used as a useful complement to the remote sensing information and facilitate water complex spectral unmixing. Taking Chaohu as an example, the paper applies the HJ-1A HSI hyperspectral data and the supplemental surface spectral measurement data to discuss the mixed spectra of lake water by spatial statistics and genetic algorithm theory. By using the spatial variogram of geostatistics to simulate the distribution difference of two adjacent pixels, the space-informational decomposition model of mixed spectral in lake water is established by co-kriging genetic algorithm, which is a improved algorithm applying the spatial variogram function of neighborhood pixel as the constraint of the objective function of the genetic algorithm. Finally, the model inversion results of suspended matter concentration are verified. Compared with the conventional spectral unmixing model, the results show the correlation coefficient of the predicted and measured value of suspended sediment concentration is 0.82, the root mean square error 9.25 mg x L(-1) by mixed spectral space information decomposition model, so the correlation coefficient is increased by 8.9%, the root mean square error reduced by 2.78 mg x L(-1), indicating that the model of suspended matter concentration has a strong predictive ability. Therefore, the effective combination of spatial and spectral information of water, can avoid inversion result distortion due to weak spectral signal of water color parameters, and large amount of calculation of information extraction because of the high spectral band numbers, and also provides an effective way to solve spectral mixture model of complex water and improve the accuracy of model inversion.

Thermoresponsive ketoprofen-imprinted monolith prepared in ionic liquid.

A thermoresponsive imprinted monolith with the ability of molecular recognition for ketoprofen was prepared for the first time. The smart monolith was synthesized in a stainless steel column using acrylamide (AAm) and 2-acrylamide-2-methyl propanesulfonic acid (AMPS) as functional monomers, which can form interpolymer complexation to restrict access of the analyte to the imprinted networks at low temperatures. To avoid a high back pressure of the column derived from neat dimethyl sulfoxide (DMSO) as a porogenic solvent that is needed to solve polar AMPS, an ionic liquid, [BMIM]BF4, was introduced into the pre-polymerization mixture. The molecular recognition ability towards ketoprofen of the resulting thermoresponsive molecularly imprinted polymer (MIP) monolith displayed significant dependence on temperature compared with a non-imprinted column (NIP), and the greatest imprinting factor was achieved at the transition temperature of 35 °C (above 10). Furthermore, the number of binding sites of the smart MIP monolith at 35 °C was about 76 times as large as that at 25 °C. In addition, Freundlich analyses indicated that the thermoresponsive MIP monolith had homogeneous affinity sites at both 25 and 35 °C with heterogeneity index 0.9251 and 0.9851, respectively.

High-efficient separation of deoxyribonucleic acid from pathogenic bacteria by hedgehog-inspired magnetic nanoparticles microextraction.

Efficient separation of deoxyribonucleic acid (DNA) through magnetic nanoparticles (MN) is a widely used biotechnology. Hedgehog-inspired MNs (HMN) possess a high-surface-area due to the distinct burr-like structure of hedgehog, but there is no report about the usage of HMN for DNA extraction. Herein, to improve the selection of MN and illustrate the performance of HMN for DNA separation, HMN and silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2) were fabricated and compared for the high-efficient separation of pathogenic bacteria of DNA. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are typical Gram-negative and Gram-positive bacteria and are selected as model pathogenic bacteria. To enhance the extraction efficiency of two kinds of MNs, various parameters, including pretreatment, lysis, binding and elution conditions, have been optimized in detail. In most separation experiments, the DNA yield of HMN was higher than that of Fe3O4@SiO2. Therefore, a HMN-based magnetic solid-phase microextraction (MSPE) and quantitative real-time PCR (qPCR) were integrated and used to detect pathogenic bacteria in real samples. Interestingly, the HMN-based MSPE combined qPCR strategy exhibited high sensitivity with a limit of detection of 2.0 × 101 CFU mL-1 for E. coli and 4.0 × 101 CFU mL-1 for S. aureus in orange juice, and 2.8 × 102 CFU mL-1 for E. coli and 1.1 × 102 CFU mL-1 for S. aureus in milk, respectively. The performance of the proposed strategy was significantly better than that of commercial kit. This work could prove that the novel HMN could be applicable for the efficient separation of DNA from complex biological samples.

Development of an Integrated Disposable Device for SARS-CoV-2 Nucleic Acid Extraction and Detection.

Objective: To develop a highly sensitive and rapid nucleic acid detection method for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: We designed, developed, and manufactured an integrated disposable device for SARS-CoV-2 nucleic acid extraction and detection. The precision of the liquid transfer and temperature control was tested. A comparison between our device and a commercial kit for SARS-Cov-2 nucleic acid extraction was performed using real-time fluorescence reverse transcription polymerase chain reaction (RT-PCR). The entire process, from SARS-CoV-2 nucleic acid extraction to amplification, was evaluated. Results: The precision of the syringe transfer volume was 19.2 ± 1.9 µL (set value was 20), 32.2 ± 1.6 (set value was 30), and 57.2 ± 3.5 (set value was 60). Temperature control in the amplification tube was measured at 60.0 ± 0.0 °C (set value was 60) and 95.1 ± 0.2 °C (set value was 95) respectively. SARS-Cov-2 nucleic acid extraction yield through the device was 7.10 × 10 6 copies/mL, while a commercial kit yielded 2.98 × 10 6 copies/mL. The mean time to complete the entire assay, from SARS-CoV-2 nucleic acid extraction to amplification detection, was 36 min and 45 s. The detection limit for SARS-CoV-2 nucleic acid was 250 copies/mL. Conclusion: The integrated disposable devices may be used for SARS-CoV-2 Point-of-Care test (POCT).

Carprofen-imprinted monolith prepared by reversible addition-fragmentation chain transfer polymerization in room temperature ionic liquids.

To obtain fast separation, ionic liquids were used as porogens first in combination with reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare a new type of molecularly imprinted polymer (MIP) monolith. The imprinted monolithic column was synthesized using a mixture of carprofen (template), 4-vinylpyridine, ethylene glycol dimethacrylate, [BMIM]BF4, and chain transfer agent (CTA). Some polymerization factors, such as template-monomer molar ratio, the degree of crosslinking, the composition of the porogen, and the content of CTA, on the column efficiency and imprinting effect of the resulting MIP monolith were systematically investigated. Affinity screening of structurally similar compounds with the template can be achieved in 200 s on the MIP monolith due to high column efficiency (up to 12,070 plates/m) and good column permeability. Recognition mechanism of the imprinted monolith was also investigated.

[Retrieval of atmospheric CO2 from ground-based high resolution FTS spectra].

Atmospheric carbon dioxide is a key greenhouse gas. Global monitoring of carbon dioxide would be helpful to improving the understanding of climate change. Ground-based observations usually have higher resolution and signal-to-noise ratio and more known parameters than satellite-based observations, which make it easier to achieve a better retrieval precision Ground-based retrieval method could be extended to satellite scenarios, and it could also provide validation for satellite data. The main procedure of the retrieval method was established, and this procedure was validated by simulated retrieval. It was proved that the method could get reasonable results under certain system errors. The retrieval of ground-based FTS spectra showed that this method has a potential to obtain atmospheric carbon dioxide column information.

[Study of the effect of surface reflectance on atmospheric CO2 retrieval and ratio spectrometry].

Retrieving atmospheric CO2 concentration from space-based infrared measurements is an ill-posed problem, and the uncertainty of ground properties is an important impacting factor. For the requirement of high precision retrieval of atmospheric CO2, the effects of surface reflectance must be corrected. Thus a surface reflectance correction method is proposed. In this correction method, the selection of non-CO2 absorption (off-line) channel is an important part, so several different types of off-line channels were compared and analyzed. We finally found that averaging all data of multi-channels as off-line channel is the best way, in which the retrieval precision is highest and dispersion is lowest, because the advantage is that averaging many data can reduce random error. The effects of surface reflectance on CO2 retrieval decreased significantly after correction using ratio spectrometry combined with the selected off-line channel, and CO2 retrieval precision improved greatly.

Bioconjugation of nanozyme and natural enzyme for ultrasensitive detection of cholesterol.

When nanozymes are used in biological analysis, higher activity can improve the detection sensitivity, and better selectivity can eliminate other interference. To improve the specificity and sensitivity, we fabricated an innovative bioconjugated nanozyme with natural enzyme (BNNZ), in which natural ChOx was immobilized onto histidine-modified Fe3O4 (His-Fe3O4) with hydrophilic poly(ethylene glycol) (PEG) as a linker. ChOx could specifically catalyze the oxidation of cholesterol to generate H2O2 molecule, and then the newly formed H2O2 oxidized the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue ox-TMB by peroxidase-like His-Fe3O4. According to the above cascade reaction, the BNNZ-based colorimetric strategy was proposed for the detection of cholesterol. Wherein, natural enzymes specifically catalyzed substrates, which endowed BNNZ with excellent specificity for target molecules; meanwhile, the introduction of histidine on His-Fe3O4 effectively increased the peroxidase-like activity of BNNZ, which provided a guarantee for sensitivity. Furthermore, BNNZ after reaction could be rapidly separated by an external magnetic field without interfering with colorimetric quantitative detection. The proposed strategy exhibited excellent sensitivity with limit of detection of 0.446 µM and was successfully used for the detection of cholesterol in spiked human serum sample with recovery and relative standard deviation in the range of 97.9-103.5% and 2.5-4.0%, respectively. This work indicates that the bioconjugation of nanozyme and natural enzyme may be a universal strategy for synthesis of high-performance enzyme-nanozyme systems, and the new-type BNNZ will be widely used in biological detection and disease treatment.

Improving performance of cell imprinted PDMS by integrating boronate affinity and local post-imprinting modification for selective capture of circulating tumor cells from cancer patients.

Efficient capture of circulating tumor cells (CTCs) from cancer patients is an important technique that may promote early diagnosis and prognosis monitoring of cancer. However, the existing systems have certain disadvantages, such as poor selectivity, low capture efficiency, consumption of antibodies, and difficulty in release of CTCs for downstream analysis. Herein, we fabricated an innovative PEGylated boronate affinity cell imprinted polydimethylsiloxane (PBACIP) for highly efficient capture of CTCs from cancer patients. The antibody-free PBACIP possessed hierarchical structure of imprinted cavities, which were inlaid with boronic acid modified SiO2 nanoparticles (SiO2@BA), so it could specifically capture target CTCs from biological samples due to the synergistic effect of boronate affinity and cell imprinting. Furthermore, PEGylation was accurately completed in the non-imprinted region by the template cells occupying the imprinted cavity, which not only retained the microstructure of original imprinted cavities, but also endowed PBACIP with hydrophilicity. The artificial PBACIP could efficiently capture human breast-cancer cells from biological sample. When 5 to 500 SKBR3 cells were spiked in 1 mL mice lysed blood, the capture efficiency reached 86.7 ± 11.5% to 96.2 ± 2.3%. Most importantly, the PBACIP was successfully used to capture CTCs from blood of breast cancer patients, and the captured CTCs were released for subsequent gene mutation analysis. The PBACIP can efficiently capture and release CTCs for downstream analysis, which provides a universal strategy toward individualized anti-tumor comprehensive treatments and has great potential in the future cell-based clinical applications.

Synthesis of micron-sized magnetic agarose beads chelated with nickel ions towards the affinity-based separation of histidine-tagged/rich proteins.

Developing high-performance magnetic particles for the effective separation and purification of target proteins has become an important topic in the area of biomedical research. In this work, a simple and novel strategy was proposed for fabricating magnetic Fe3O4@agarose-iminodiacetic acid-Ni microspheres (MAIN), which can efficiently and selectively isolate histidine-tagged/rich proteins (His-proteins). Based on the thermoreversible sol-gel transition of agarose, basic magnetic agarose microspheres were prepared through the inverse emulsion method, in which the emulsion contained agarose and amine-modified Fe3O4 nanoparticles. The size of the emulsion was controlled by the emulsification of a high-speed shear machine, which improved the specific surface area of MAIN. Subsequently, the amine-modified Fe3O4 nanoparticles were covalently crosslinked with agarose through epichlorohydrin, which could avoid leakage of the magnetic source during use and increase the stability of MAIN. The microsized MAIN exhibited a clearly visible spherical core-shell structure with a diameter range from 3.4 µm to 9.8 µm, and excellent suspension ability in aqueous solution. The maximum adsorption capacity of MAIN for histidine-rich bovine hemoglobin was 1069.2 mg g-1 at 35 °C, which was higher than those of commercialized and most reported magnetic agarose microspheres/nanoparticles. The MAIN showed excellent adsorption ability and selectivity toward His-proteins in a mixture of histidine-rich bovine serum albumin (BSA) and histidine-poor lysozyme (LYZ). When the amount of LYZ was 5-fold higher than that of BSA, the recovery of BSA reached 75.0%. To prove its practicability, MAIN was successfully employed for the enrichment of histidine-tagged RSV-F0 from the cell culture medium supernatant. According to the optimized conditions, MAIN could enrich approximately 0.1 mg of RSV-F0 from 1 mL of complex biological sample. Therefore, we believe that the novel MAIN could be applicable for efficient separation and purification of His-proteins from complex biological systems.

Functionalized pyrite nanozyme probe and imprinted polymer modified with hydrophilic layer for rapid colorimetric analysis of glycoprotein in serum.

The biological molecules used in the sandwich detection method have problems such as complex extraction processes, high costs, and uneven quality. Therefore we integrated glycoprotein molecularly controllable-oriented surface imprinted magnetic nanoparticles (GMC-OSIMN) and boric acid functionalized pyrite nanozyme probe (BPNP) to replace the traditional antibody and horseradish peroxidase for sensitive detection of glycoproteins through sandwich detection. In this work, a novel nanozyme functionalized with boric acid was used to label glycoproteins that were captured by GMC-OSIMN. The substrate in the working solution catalyzed by the nanozyme labeled on the protein underwent visible color changes to the naked eye, and the generated signal can be quantitatively detected by a spectrophotometer, and the best color development conditions of the novel nanozyme under the influence of many factors were determined through multi-dimensional investigation. The optimum conditions of sandwich are optimized with ovalbumin (OVA), and it was extended to the detection of transferrin (TRF) and alkaline phosphatase (ALP) in the application. The detection range for TRF was 2.0 × 10-1-1.0 × 104 ng mL-1 with a detection limit of 1.32 × 10-1 ng mL-1, The detection range for ALP was 2.0 × 10-3-1.0 × 102 U L-1 with the detection limit of 1.76 × 10-3 U L-1. This method was subsequently used to detect TRF and ALP levels in 16 liver cancer patients, and the standard deviation of the test results of each patient was less than 5.7%.