Influence of Spider Silk Protein Structure on Mechanical and Biological Properties for Energetic Material Detection.

Spider silk protein, renowned for its excellent mechanical properties, biodegradability, chemical stability, and low immune and inflammatory response activation, consists of a core domain with a repeat sequence and non-repeating sequences at the N-terminal and C-terminal. In this review, we focus on the relationship between the silk structure and its mechanical properties, exploring the potential applications of spider silk materials in the detection of energetic materials.

Optimized silk fibroin nanoparticle functionalization with anti-CEA nanobody enhancing active targeting of colorectal cancer cells.

This work aimed to establish a simple and feasible method to obtain silk fibroin nanoparticles (SFNPs) with uniform particles size, and then modify the SFNPs with nanobody (Nb) 11C12 targeting the proximal membrane end of carcinoembryonic antigen on the surface of colorectal cancer (CRC) cells. The regenerated silk fibroin (SF) was isolated using ultrafiltration tubes with a 50 kDa molecular weight cut-off, and the retention fraction (named as SF > 50 kDa) was further self-assembled into SFNPs by ethanol induction. Scanning electron microscope (SEM) and high-resolution transmission electron microscop showed that the SFNPs with uniform particles size were formed. Due to electrostatic adsorption and pH responsiveness, SFNPs have been proved to effectively load and release the anticancer drug doxorubicin hydrochloride (DOX) (DOX@SFNPs). Further, targeting molecule Nb 11C12 was used to modify these nanoparticles, constituting the targeted outer layer of the drug delivery system (DOX@SFNPs-11C12), achieving precise localization to cancer cells. The release amount of DOX observed fromin vitrodrug release profiles increased as follows: pH 7.4 < pH 6.8 < pH 5.4, demonstrating that the DOX release could be accelerated in a weakly acidic environment.In vitrocytotoxicity experiments displayed that SFNPs-11C12 nanoparticles exhibited good safety and biocompatibility. Drug-loaded nanoparticles, DOX@SFNPs-11C12, led to higher LoVo cells apoptosis compared to DOX@SFNPs. Fluorescence spectrophotometer characterization and confocal laser scanning microscopy further showed that the internalization of DOX was highest in the DOX@SFNPs-11C12, certifying that the introduced targeting molecule enhanced the uptake of drug delivery system by LoVo cells. This study provides a simple and operational approach to developing an optimized SFNPs drug delivery system modified by targeting Nb, which can be a good candidate for CRC therapy.

A Job Demands-Resources Perspective on Kindergarten Principals' Occupational Well-Being: The Role of Emotion Regulation.

The position of school principal is emotionally demanding. Principals' occupational well-being (OWB) can be influenced by their emotional work characteristics, and their emotional regulation plays a critical role. Based on the job demands-resources (JD-R) model, this study investigated the relationships between kindergarten principals' OWB and its complex antecedents. Specifically, the study examined the influences among emotional job demands and trust in colleagues on kindergarten principals' OWB factors (job satisfaction and emotional exhaustion), with a particular focus on the role of their emotion regulation strategies. Through an investigation of 618 kindergarten principals in China, the results showed that emotional job demands and trust in colleagues had different influences on principals' OWB dimensions. Emotional job demands can enhance both principals' suppression and reappraisal strategies, and trust in colleagues functions as an interpersonal resource for reappraisal. Principals' emotion regulation strategies mediated the influence of work characteristics on OWB. Reappraisal is an important personal resource that can buffer the influence of work demands on OWB. The results may extend our understanding of principals' emotional work. The implications on principals' work and emotion regulation were further discussed.

High-Strength Collagen-Based Composite Films Regulated by Water-Soluble Recombinant Spider Silk Proteins and Water Annealing.

Spider silk has attracted extensive attention in the development of high-performance tissue engineering materials because of its excellent physical properties, biocompatibility, and biodegradability. Although high-molecular-weight recombinant spider silk proteins can be obtained through metabolic engineering of host bacteria, the solubility of the recombinant protein products is always poor. Strong denaturants and organic solvents have thus had to be exploited for their dissolution, and this seriously limits the applications of recombinant spider silk protein-based composite biomaterials. Herein, through adjusting the temperature, ionic strength, and denaturation time during the refolding process, we successfully prepared water-soluble recombinant spider major ampullate spidroin 1 (sMaSp1) with different repeat modules (24mer, 48mer, 72mer, and 96mer). Then, MaSp1 was introduced into the collagen matrix for fabricating MaSp1-collagen composite films. The introduction of spider silk proteins was demonstrated to clearly alter the internal structure of the composite films and improve the mechanical properties of the collagen-based films and turn the opaque protein films into transparency ones. More interestingly, the composite film prepared with sMaSp1 exhibited better performance in mechanical strength and cell adhesion compared to that prepared with water-insoluble MaSp1 (pMaSp1), which might be attributed to the effect of the initial dissolved state of MaSp1 on the microstructure of composite films. Additionally, the molecular weight of MaSp1 was also shown to significantly influence the mechanical strength (enhanced to 1.1- to 2.3-fold) and cell adhesion of composite films, and 72mer of sMaSp1 showed the best physical properties with good bioactivity. This study provides a method to produce recombinant spider silk protein with excellent water solubility, making it possible to utilize this protein under environmentally benign, mild conditions. This paves the way for the application of recombinant spider silk proteins in the development of diverse composite biomaterials.

Accuracy improvement in plastics classification by laser-induced breakdown spectroscopy based on a residual network.

The whole ecosystem is suffering from serious plastic pollution. Automatic and accurate classification is an essential process in plastic effective recycle. In this work, we proposed an accurate approach for plastics classification using a residual network based on laser-induced breakdown spectroscopy (LIBS). To increasing efficiency, the LIBS spectral data were compressed by peak searching algorithm based on continuous wavelet, then were transformed to characteristic images for training and validation of the residual network. Acrylonitrile butadiene styrene (ABS), polyamide (PA), polymethyl methacrylate (PMMA), and polyvinyl chloride (PVC) from 13 manufacturers were used. The accuracy of the proposed method in few-shot learning was evaluated. The results show that when the number of training image data was 1, the verification accuracy of classification by plastic type under residual network still kept 100%, which was much higher than conventional classification algorithms (BP, kNN and SVM). Furthermore, the training and testing data were separated from different manufacturers to evaluate the anti-interference properties of the proposed method from various additives in plastics, where 73.34% accuracy was obtained. To demonstrate the superiority of classification accuracy in the proposed method, all the evaluations were also implemented by using conventional classification algorithm (kNN, BP, SVM algorithm). The results confirmed that the residual network has a significantly higher accuracy in plastics classification and shows great potential in plastic recycle industries for pollution mitigation.

Development and characterization of a photo-cross-linked functionalized type-I collagen (Oreochromis niloticus) and polyethylene glycol diacrylate hydrogel.

Collagen hydrogels have been widely investigated as scaffolds for tissue engineering due to their biocompatibility and capacity to promote cell adhesion. However, insufficient mechanical strength and rapid degradation properties remain the major obstacles for their applications. In the present study, type-I tilapia collagen (TC) was functionalized to form methacrylated tilapia collagen (MATC) by introducing methacrylic acid, developing a photo-cross-linked PEGDA-MATC hydrogel. The mechanical strength of PEGDA-MATC hydrogel could be tuned by adjusting the pH of the precursor solutions, which was decreased with the pH increased. At a pH 5 condition, PEGDA-MATC showed the highest compressive fracture stress (1.31 MPa). Compared to the PEGDA-TC hydrogel, PEGDA-MATC hydrogel exhibited similar swelling behavior to PEGDA-TC hydrogel in PBS solutions, but higher residual mass ratio (PEGDA-MATC, 213.2 ± 2.8%) than PEGDA-TC hydrogel (199.4 ± 3.8%) when cultured with type-I collagenase. PEGDA-MATC hydrogel showed sustained BSA release capacity for 6 days, and the BSA release ratio was significantly (p < 0.05) decreased with increasing concentration of loaded-BSA (68.6% at 4 mg mL-1, 42.2% at 8 mg mL-1). The PEGDA-MATC hydrogel allowed cell adhesion and proliferation in vitro. These results demonstrated that PEGDA-MATC hydrogel might be a potential scaffold for tissue engineering applications.

The promising indicators of the thermal and mechanical properties of collagen from bass and tilapia: synergistic effects of hydroxyproline and cysteine.

Collagen has been widely documented as one of the most promising and competitive biomaterials for tissue engineering and medical applications. However, the properties of collagen differ from one source to another. In the present study, type I collagen (COL-I) was extracted and purified from the skins of Japanese sea bass (Lateolabrax japonicus) and Nile tilapia (Oreochromis niloticus). Ultraviolet (UV) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE were performed to characterize both COL-Is. The denaturing temperature of bass collagen (BC) was observed to be 27.2 °C, and 35.3 °C for tilapia collagen (TC). The content of hydroxyproline was 13.4% in TC, which was similar to that in porcine collagen (PC, 13.6%) and higher than that in BC (10.3%), while the content of cysteine in TC (0.87%) was significantly higher than that in PC (0.04%) and BC (0.35%). After incubation at different temperatures for 9 h, more degraded collagen bands appeared in the BC hydrogel (BCH) group than in the TC hydrogel (TCH) group, indicating that TCH exhibited better thermal stability than BCH. The thermal stabilities of TCH and PC hydrogel (PCH) were similar. The compressive stress of TCH was up to 0.099 MPa, while it was 0.047 MPa for BCH and 0.003 MPa for PCH. These results demonstrated that the content of amino acids (especially hydroxyproline and cysteine) has a synergistic effect on the thermal and mechanical properties of BCH, TCH and PCH, which would be an indicator of the thermal and mechanical properties of collagen hydrogels in future studies.

A simple and efficient purification platform for monoclonal antibody production based on chromatin-directed cell culture clarification integrated with precipitation and void-exclusion anion exchange chromatography.

Protein A affinity chromatography, featured by its robustness and high-specificity, is still dominant as a first capture step for the purification of immunoglobulin G monoclonal antibodies (IgG mAbs). However, the material and operational costs of protein A are universally recognized as high, and its productivity is also limited as column mode. In order to overcome these limitations, industry is increasingly considering the use of non-protein A-based processes for IgG purification. In this study, sodium citrate precipitation (SCP) was developed as the primary purification step, and chromatin-directed cell culture clarification was demonstrated to significantly elevate the purification capability. Additional 0.05% (w/v) of Tween 20 was shown to effectively reduce the residual free antibody light chain (LC) during precipitation. The resuspended IgG was further polished by void-exclusion anion exchange chromatography (VEAX), which supported protein loading without buffer adjustment. The non-histone host cell protein (nh-HCP) content in the final product was about 5ppm and histone HCP below limit of detection (LOD). DNA was reduced to less than 1ppb, and aggregates/free LC less than 0.1%. The overall IgG recovery was 87.2%. A simple and efficient purification platform with only one-column step was therefore established, providing a more promising alternative to the current prevailing protein A-based purification platforms.

[Improved protein-A chromatography for monoclonal antibody purification].

Therapeutic monoclonal antibodies become the major product class within the biopharmaceutical market. Protein A as the first capture step is still dominant in current platforms for purification of monoclonal antibodies. In this study, we developed a new antibody harvest process that incorporates acidic treatment of cell harvest, demonstrating high process yield, improved clearance of host cell associated contaminants, like non-histone host cell protein, histone, DNA and heteroaggregates. Host protein contamination was reduced about 10-fold compared to protein A loaded with harvest clarified by centrifugation and microfiltration. Turbidity increase of eluted IgG upon pH neutralization was nearly eliminated. Residual levels of impurities in the protein A eluate were achieved that potentially meet requirements of drug substance and thus alleviate the burden for further impurities removal in subsequent chromatography steps. The mechanism of host cell associated contaminants removal during acidic treatment was also explored. After a polishing step by Capto adhere, host cell protein was reduced to less than 5 ppm, DNA less than 1 ppb, histone to undetectable level, heteroaggregates less than 0.01% with total IgG recovery around 87%. This efficient process can be easily integrated into current IgG purification platforms, and may overcome downstream processing challenges.