Rapid identification of antibody impurities in size-based electrophoresis via CZE-MS generated spectral library.

Methods for the reliable and effective detection and identification of impurities are crucial to ensure the quality and safety of biopharmaceutical products. Technical limitations constrain the accurate identification of individual impurity peaks by size-based electrophoresis separations followed by mass spectrometry. This study presents a size-based electrophoretic method for detecting and identifying impurity peaks in antibody production. A hydrogen sulfide-accelerated degradation method was employed to generate known degradation products observed in bioreactors that forms the basis for size calibration. LabChip GXII channel electrophoresis enabled the rapid (< 1 min) detection of impurity peaks based on size, while capillary zone electrophoresis-mass spectrometry (CZE-MS) facilitated their accurate identification. We combine these techniques to examine impurities resulting from cell culture harvest conditions and forced degradation to assess antibody stability. To mimic cell culture harvest conditions and the impact of forced degradation, we subjected samples to cathepsin at different pH buffers or exposed them to high pH and temperature. Our method demonstrated the feasibility and broad applicability of using a CZE-MS generated spectral library to unambiguously assign peaks in high throughput size-based electrophoresis (i.e., LabChip GXII) with identifications or likely mass of the antibody impurity. Overall, this strategy combines the utility of CZE-MS as a high-resolution separation and detection method for impurities with size-based electrophoresis methods that are typically used to detect (not identify) impurities during the discovery and development of antibody therapeutics.

Are workers also vulnerable to the impact of ambient air pollution? Insight from a large-scale ventilatory exam.

It remains unclear how ambient air pollution may affect the prevalence of obstructive ventilatory dysfunction (OVD) among workers. We aim to assess the association of a comprehensive set of ambient air pollutants with OVD prevalence in workers and to explore the potential interactive effects of the occupational factors. This is a population-based cross-sectional study among 305,022 participants from the Guangdong Province, China. Mixed-effects models were used to obtain differences in the OVD risk associated with a 10 µg/m3 increase in ambient air pollution. We found that for each 10 µg/m3 increase in PM2.5, PM10, PM coarse, O3, and NO2 concentrations, the odds ratio (OR) for OVD in workers is 1.324 (95 % confidence interval (CI), 1.282-1.367), 1.292 (95 % CI, 1.268-1.315),1.666 (95 % CI, 1.614-1.719), 1.153 (95 % CI, 1.142-1.165), and 1.023 (95 % CI, 1.012-1.033). We observed that young participants (18-38 years old), women, participants with longer years of service (>48 months), participants working in large enterprises, professional skills workers, and production and manufacturing workers have higher estimated effects. In addition, we also found that workers exposed to high temperatures have higher estimated effects under air pollutants exposure, while workers exposed to noise have higher estimated effects under PM2.5, PM10, NO2, and O3 exposure. Workers exposed to dust have a lower risk of developing OVD under exposure to ambient air pollutants compared to those not exposed. Our results indicate that ambient air pollution increases the risk of OVD in workers. Moreover, air pollutants exhibit a greater estimated effect among workers exposed to high temperatures or noise. Our research findings highlight the importance of fully considering the impact of ambient air pollution on protecting the respiratory health of workers.

Carboxymethyl chitosan/sodium alginate hydrogels with polydopamine coatings as promising dressings for eliminating biofilm and multidrug-resistant bacteria induced wound healing.

Microorganisms induced wound infection and the accompanying excessive inflammatory response is the daunting problems in wound treatment. Due to the lack of corresponding biological functions, traditional wound dressings cannot effectively protect the wound and are prone to induce local infection, excessive inflammation, and vascular damage, resulting in prolonged unhealing. Here, a mussel-inspired strategy was adopted to prepare a multifunctional hydrogel created by H2O2/CuSO4-induced rapid polydopamine (PDA) deposition on carboxymethyl chitosan (CMC)/sodium alginate (Alg) based hydrogel, termed as CAC/PDA/Cu(H2O2). The prepared CAC/PDA/Cu(H2O2) hydrogel features excellent biocompatibility, adequate mechanical properties, and good degradability. Moreover, the CAC/PDA/Cu(H2O2) hydrogel can not only realize antibacterial, and anti-inflammatory effects, but also promote angiogenesis to accelerate wound healing in vitro thanks to the composite PDA/Cu(H2O2) coatings. Significantly, CAC/PDA/Cu(H2O2) hydrogel illustrates excellent therapeutic effects in Methicillin-resistant Staphylococcus aureus (MRSA) induced-rat infection models, which can efficiently eliminate MRSA, dramatically reduce inflammatory expression, promote angiogenesis, and ultimately shorten the wound healing time. CAC/PDA/Cu(H2O2) hydrogel exhibited the best wound healing rate on days 7 (80.63 ± 2.44 %), 11 (92.45 ± 2.26 %), and 14 (97.86 ± 0.66 %). Thus, the multifunctional hydrogel provides a facile and efficient approach to wound management and represents promising potential in the therapy for wound healing.

Peroxide stabilizers remarkably increase the longevity of thermally activated peroxydisulfate for enhanced ISCO remediation.

Thermally activated peroxydisulfate In Situ Chemical Oxidation (TAP-ISCO) is often applied for the remediation of soil-sorbed hydrophobic organic contaminants (HOCs) and nonaqueous phase liquids (NAPLs), which act as long-term sources of groundwater contamination. TAP-ISCO benefits from improved desorption/dissolution of organic contaminants into the aqueous phase and efficient activation of peroxydisulfate at elevated temperatures, but the primary limitation of TAP-ISCO is the short lifetime of peroxydisulfate (therefore the availability of reactive radical species). To resolve this problem, coupling of peroxide stabilizers with TAP were tested. The compatibility of seven representative commercial organic and inorganic peroxide stabilizers, including sodium stannate, trisodium phosphate, sodium pyrophosphate, sodium silicate, sodium citrate, ethylene diamine tetra methylene phosphonic acid and ethylenediaminetetraacetic acid disodium salt, with TAP in aqueous solutions and solutions containing goethite or soil particles were first studied. The effects of stabilizers on the formation, distribution and reactivity of reactive oxygen species were then investigated through electron paramagnetic resonance (EPR) spin-trapping experiments using 5,5-dimethyl-1-pyrroline-N-oxide, chemical probe experiments using anisole, nitrobenzene and hexachloroethane, and biphasic trichloroethylene (TCE) dense nonaqueous phase liquids (DNAPLs) TAP-ISCO mimicking experiments. The results indicate that organic stabilizers significantly accelerate peroxydisulfate decomposition at both ambient and elevated temperatures. In contrast, inorganic stabilizers can markedly increase peroxydisulfate longevity by suppressing the acid-catalyzed peroxydisulfate decomposition, quenching radical-chain acceleration, and sequestering transition metal species. In addition, TAP systems containing inorganic stabilizers can effectively generate a variety of reactive radical species, including SO4•-, HO•, and O2•-, and improve the oxidation of anisole and nitrobenzene, though suppressing the reduction of hexachloroethane to some extent. Especially, suitable inorganic stabilizers (e.g., trisodium phosphate) can effectively improve TAP oxidation of TCE DNAPL while suppressing peroxydisulfate decomposition. Overall, this study provides the fundamental basis of coupling TAP-ISCO with peroxide stabilizers.

Image-enhanced single-pixel imaging using fractional calculus.

Recent years, image enhancement for single-pixel imaging has developed rapidly and provides an image-free way for extracting image information. However, the conventional image enhancement approaches for single-pixel imaging are still based on the discontinuously adjustable operations such as integer-order derivatives, which are frequently used in edge detection but sensitive to the image noise. Therefore, how to balance between two conflicting demands, i.e. edge detection and noise suppression, is a new challenge. To address this issue, we introduce arbitrary-order fractional operations into single-pixel imaging. In experiment, the proposed technique has the capacity to detect image edges with high quality. Compared with integer-order derivative method which amplifies noise significantly while extracting edges, it offers a nice tradeoff between image SNR and performance of edge enhancement. In addition, it also shows good performance of image smoothing and improvement of image quality, if fractional order is negative. The proposed technique provides the adjustable fractional order as a new degree of freedom for edge extraction and image de-noising and therefore makes up for the shortcomings of traditional method for image enhancement.

Theoretical and experimental study of hybrid optical computing engine for arbitrary-order FRFT.

Fractional Fourier transform (FRFT) is the generalization of Fourier transform. It provides many significant advantages, such as fractional order as the new degree of freedom and high efficiency and great performance for non-stationary signal analysis/processing, that other operations including Fourier transform cannot. Here, we report a hybrid optical system for computation of arbitrary-order FRFT of temporal signals. In experiment, the fractional-domain information of input temporal signals could be directly acquired by detector. In addition, the optical computing results are in good agreement with numerical results. Then we apply the optical computing engine to demodulation of chirp spread spectrum signals. Using sub-Nyquist sampling, the proposed technology could greatly save the number of measurements in demodulation. The compression ratio could be as low as 0.4%, because of the high compression performance of chirp signals in FRFT domain. As a result, the proposed technology has unique advantages in analysis and information extraction for non-stationary signals, especially for chirp-like signals, and may become a powerful optical time-frequency analysis tool for temporal signals.

Fractional Fourier single-pixel imaging.

Single-pixel imaging technology has a number of advantages over conventional imaging approaches, such as wide operation wavelength region, compressive sampling, low light radiation dose and insensitivity to distortion. Here, we report on a novel single-pixel imaging based on fractional Fourier transform (FRFT), which captures images by acquiring the fractional-domain information of targets. With the use of structured illumination of two-dimensional FRFT base patterns, FRFT coefficients of the object could be measured by single-pixel detection. Then, the object image is achieved by performing inverse FRFT on the measurements. Furthermore, the proposed method can reconstruct the object image from sub-Nyquist measurements because of the sparsity of image data in fractional domain. In comparison with traditional single-pixel imaging, it provides a new degree of freedom, namely fractional order, and therefore has more flexibility and new features for practical applications. In experiments, the proposed method has been applied for edge detection of object, with an adjustable parameter as a new degree of freedom.

Penicillic acid in fruits: method development, validation by liquid chromatography-tandem mass spectrometry and survey in southern China.

BACKGROUND: Penicillic acid (PA) is produced by Aspergillus spp. and Penicillium spp., which are common postharvest and storage fungi of fruits. PA can be of concern for human health because of its toxicity and high fruit consumption by the population. However, no data on PA occurrence in various fruits have yet been reported. A quick, easy, cheap, effective, rugged and safe (QuEChERS) approach for PA determination in various fruits was developed and applied to explore PA incidence in fruits. RESULTS: The modified QuEChERS procedure with extraction by ethyl acetate and purification by multi-walled carbon nanotubes (MWCNTs), primary secondary amine (PSA) and octadecyl silane (C18) was established to determine PA in various fruits by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The average recoveries were 72.9-102.2% and relative standard deviations (RSDs) were 1.3-7.9%. A total of 161 fruits samples, including kiwi, apple, peach, grape and mandarin/orange, were collected in southern China. The incidence of PA in fruits was 14.9% and the levels of PA contamination were 0.200-0.596 µg kg-1 . Our results suggested that orange/mandarin, grape and kiwi were favorable matrices for Aspergillus spp. and Penicillium spp. to produce PA, rather than peach and apple. CONCLUSION: To the best of our knowledge, this is the first report about PA contamination in various fruits in China. Our study emphasizes the necessity of the current established method, which could be used for continuous monitoring of PA and reducing the health risk to Chinese consumers. © 2020 Society of Chemical Industry.

Adaptive ghost imaging.

Traditional ghost imaging applies correlated algorithms to reconstruct the image of an object. However, it fundamentally requires some spatial distributions of the correlated light beam, e.g. random illumination, which hardly exists in reality. Here, different from the localized analysis used in the traditional ghost imaging, a spatial and temporal global analysis of the whole measurements is proposed. Therefore, we demonstrate a new ghost imaging modality, called adaptive ghost imaging (AGI), that utilizes the difference of successive frames as the correlation pattern to generate the image. As a result, AGI can work with any varying illuminations including, but not limited to, random illumination. We believe that AGI will make the ghost imaging easier, more applicable and closer to reality.

Speckle reducing OCT using optical chopper.

Optical coherence tomography (OCT) has been an important and powerful tool for biological research and clinical applications. However, speckle noise significantly degrades the image quality of OCT and has a negative impact on the clinical diagnosis accuracy. In this paper, we propose a novel speckle noise suppression technique which changes the spatial distribution of sample beam using a special optical chopper. Then a series of OCT images with uncorrelated speckle patterns could be captured and compounded to improve the image quality without degradation of resolution. Typical signal-to-noise ratio improvement of ∼6.4 dB is experimentally achieved in tissue phantom imaging with average number n = 100. Furthermore, compared with conventional OCT, the proposed technique is demonstrated to view finer and clearer biological structures in human skin in vivo, such as sweat glands and blood vessels. The advantages of low cost, simple structure and compact integration will benefit the future design of handheld or endoscopic probe for biomedical imaging in research and clinical applications.

Overlooked pathways of denitrification in a sulfur-based denitrification system with organic supplementation.

Elemental sulfur-driven autotrophic denitrification (SADN) is a cost-effective approach for treating secondary effluent from wastewater treatment plants (WWTPs). Additional organics are generally supplemented to promote total nitrogen (TN) removal, reduce nitrite accumulation and sulfate production, and balance the pH decrease induced by SADN. However, understanding of the impacts of organic supplementation on microbial communities, nitrogen metabolism, denitrifier activity, and SADN rates in sulfur-based denitrification reactors is still limited. Here, a sulfur-based denitrification reactor was continuously operated for 272 days during which six different C/N ratios were tested successively (2.7, 1.5, 0.7, 0.5, 0.25, and 0). Organic supplementation improved TN removal and decreased NO2- accumulation, but reduced the relative abundance of denitrifiers and the contribution of autotrophic nitrate-reducing bacteria (aNRB) to TN removal during the long-term operation of reactor. Predictive functional profiling showed that nitrogen metabolism potential increased with decreasing C/N ratios. SADN was the predominant removal process when the C/N ratio was ≤0.7 (achieving 60% contribution when C/N = 0.7). Although organic supplementation weakened the dominant role of aNRB in denitrification, batch tests for the first time demonstrated that it could accelerate the SADN rate, attributed to the improvement of sulfur bioavailability, likely via the formation of polysulfide. A possible nitrogen removal pathway with multiple electron donors (i.e., sulfur, organics, sulfide, and polysulfide) in a sulfur-based denitrification reactor with organic supplementation was therefore proposed. However, supplementation with a high level of organics could increase the operational cost and effluent concentrations of sulfide and organics as well as enrich heterotrophic denitrifiers. Moreover, microbial community had substantial changes at C/N ratios of >0.5. Accordingly, an optimal C/N ratio of 0.25-0.5 was suggested, which could simultaneously minimize the additional operating cost associated with organic supplementation and maximize TN removal and SADN rates.

Different ferric dosing strategies could result in different control mechanisms of sulfide and methane production in sediments of gravity sewers.

Ferric salt dosing is widely used to mitigate sulfide and methane emissions from sewers. In gravity sewers with sediments, responses of sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) residing in different zones to Fe3+ dosing strategies still remain unknown. In this study, we investigated the changes in behavior of SRB and MA in different depths of sewer sediment using laboratory-scale sewer sediment reactors with different Fe3+ dosing strategies (different instant dosages and frequencies). All Fe3+ dosing strategies examined efficiently suppressed sulfide concentration for a short time, but the control mechanisms were different. When a low-dosage, high-frequency Fe3+ dosing strategy was employed, Fe3+ could not penetrate into the sewer sediment, therefore, the abundances of SRB and MA in all zones of sewer sediment did not change substantially. As a result, the active sulfide-producing and methane-producing zones kept unchanged. Sulfide was controlled mainly via chemical sulfide oxidation and precipitation, and methane formation was not influenced. In contrast, when a high-dosage, low-frequency Fe3+ dosing strategy was used, the SRB activity in the upper layer of the sewer sediment was nearly fully suppressed according to the down moving zones of sulfide production (from 0-5 mm to 20-25 mm) and lower sulfate reduction, in which sulfate reduction decreased by 56% in the long-term trial. The generated sulfide was further removed via chemical sulfide oxidation and precipitation. This strategy also significantly suppressed MA activity (21% reduction in methane production). However, considering a long-term satisfactory sulfide control, a low operational cost and less sediments deposited in gravity sewers, a low-dosage, high-frequency Fe3+ dosing strategy would be a more cost-effective solution for sulfide control in gravity sewers with thin (<20 mm) or thick (>20 mm) sediments if methane mitigation does not need to be taken into account.

A strategy for screening of high-quality enzyme inhibitors from herbal medicines based on ultrafiltration LC-MS and in silico molecular docking.

A novel strategy of ultrafiltration LC-MS and in silico molecular docking was proposed to discover high-quality enzyme inhibitors from herbal medicines. Using this strategy, two compounds were predicted and finally demonstrated as potent xanthine oxidase inhibitors, whose in vitro IC50 values were lower than that of a positive control allopurinol.

Affinity selection-based two-dimensional chromatography coupled with high-performance liquid chromatography-mass spectrometry for discovering xanthine oxidase inhibitors from Radix Salviae Miltiorrhizae.

Xanthine oxidase (XOD) is a key oxidative enzyme to the pathogenesis of hyperuricemia and certain diseases induced by excessive reactive oxygen species. XOD inhibitors could provide an important therapeutic approach to treat such diseases. A new method using affinity selection-based two-dimensional chromatography coupled with liquid chromatography-mass spectrometry was developed for the online screening of potential XOD inhibitors from Radix Salviae Miltiorrhizae. Based on our previous study, the two-dimensional, turbulent-flow chromatography (TFC) was changed to a mixed-mode anion-exchange/reversed-phase column and one reversed-phase column. The developed method was validated to be selective and sensitive for screening XOD-binding compounds, especially weak acidic ones, in the extracts. Three salvianolic acids were screened from the Radix Salviae Miltiorrhizae extract via the developed method. The XOD inhibitory activities of salvianolic acid C and salvianolic acid A were confirmed, and their inhibitory modes were measured. Salvianolic acid C exhibited potent XOD inhibitory activity with an IC(50) of 9.07 µM. This work demonstrated that the developed online, two-dimensional TFC/LC-MS method was effective in discovering the binding affinity of new compounds from natural extracts for target proteins, even at low concentrations.