The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective.

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.

In situ controlled release of stromal cell-derived factor-1α and antimiR-138 for on-demand cranial bone regeneration.

Bone regeneration involves complex physiological processes, which is generally regulated and controlled by multiple bioactive molecules. In situ controlled release of combined bioactive factors in a spatiotemporal sequence for adapting the demand of bone regeneration is a desired strategy. In this study, nanoparticle/hydrogel composite system was constructed by incorporating stromal cell derived factor-1α (SDF-1α) and chitosan/tripolyphosphate/hyaluronic acid/antimiRNA-138 nanoparticles (CTH/antimiR-138 NPs) in chitosan/ß-sodium glycerol phosphate (CS/GP) hydrogel for rat critical-size calvarial bone regeneration. The fast release of SDF-1α promoted the migration of mesenchymal stem cells (MSCs) for 6 d, while the sustained release of antimiR-138 from the nanoparticle/hydrogel compound enhanced the osteogenic differentiation of MSCs over 21 d. 8 weeks after surgery, calvarial specimens were evaluated by microcomputed tomography (µ-CT), histological analysis and immunohistochemistry. Comparing with blank group and hydrogel group, hydrogels incorporated with SDF-1α and/or CTH/antimiR-138 NPs significantly enhanced bone regeneration (p<0.05). In addition, the expression of collagen type-1 (COL-1), osteopontin (OPN) and osteocalcin (OCN) proteins were enhanced in the combined drug group (incorporated both SDF-1α and CTH/antimiR-138 NPs) in comparison to the hydrogel group. Our research indicated the in situ formation of NPs/hydrogel composite could provide temporal sequence-release of SDF-1α and CTH/antimiR-138 NPs for on-demand MSCs homing and cranial bone regeneration.

Improving the osteogenesis of rat mesenchymal stem cells by chitosan-based-microRNA nanoparticles.

MicroRNAs (miRNAs) play important roles in the osteogenic differentiation of stem cells. However, the application of miRNA in bone regeneration has been limited by its poor stability, low cellular uptake, and undesired immune response. In this study, chitosan (CS)/tripolyphosphate (TPP)/Hyaluronic Acid (HA) nanoparticles (CTH NPs) were prepared to deliver antimiR-138 to bone marrow mesenchymal stem cells (MSCs). The particle size, polydispersity index, and zeta potential of CTH NPs were related to the weight ratio of CS:TPP:HA. At optimum N/P ratio (20:1), the highest encapsulation efficiency was obtained. Both blank CTH NPs and CTH/antmiR-138 NPs exhibited no cytotoxicity to MSCs. A high transfection efficiency (nearly 70%) and significant enhancement of the osteogenesis of MSCs were observed. Above results demonstrated that CTH NPs was a potential candidate as an efficient non-viral miRNA vector to regulate the osteogenic differentiation of MSCs.

[Research on the Pre-Processing Methods of Wheat Hardness Prediction Model Based on Visible-Near Infrared Spectroscopy].

Grain hardness is an important quality parameter of wheat which has great influence on the classification, usage and composition research of wheat. To achieve rapid and accurate detection of wheat hardness, radial basis function (RBF) neural network model was built to predict the hardness of unknown samples on the basis of analyzing the absorptive characteristics of the composition of wheat grain in infrared, besides, the effects of different spectral pretreatment methods on the predictive accuracy of models were emphatically analyzed. 111 wheat samples were collected from major wheat-producing areas in China; then, spectral data were obtained by scanning samples. Mahalanobis distance method was used to identify and eliminated abnormal spectra. The optimized method of sample set partitioning based on joint X-Y distance (SPXY) was used to divide sample set with the number of calibration set samples being 84 and prediction set samples being 24. Successive projections algorithm (SPA) was employed to extract 47 spectral features from 262. SPA, first derivatives, second derivatives, standard normal variety (SNV) and their combinations were applied to preprocess spectral data, and the interplay of different prediction methods was analyzed to find the optimal prediction combination. Radial basis function (RBF) was built with preprocessed spectral data of calibration set being as inputs and the corresponding hardness data determined via hardness index (HI) method being as outputs. Results showed that the model got the best prediction accuracy when using the combination of SNV and SPA to preprocess spectral data, with the discriminant coefficient (R2), standard error of prediction (SEP) and ratio of performance to standard deviate (RPD) being 0.844, 3.983 and 2.529, respectively, which indicated that the RBF neural network model built based on visible-near infrared spectroscopy (Vis-NIR) could accurately predict wheat hardness, having the advantages of easy, fast and nondestructive compared with the traditional method. It provides a more convenient and practical method for estimating wheat hardness.

Expression of metastasis-associated protein 3 in human brain glioma related to tumor prognosis.

Glioma represents a disparate group of tumors characterized by high invasion ability, and therefore it is of clinical significance to identify molecular markers and therapeutic targets for better clinical management. Previously, metastasis-associated protein family (MTA) is considered to promote tumor cell invasion and metastasis of human malignancies. Recently, the newly identified MTA3 has been shown to play conflicting roles in human malignancies, while the expression pattern and potential clinical significance of MTA3 in human glioma have not been addressed yet. In the present study, we investigated the protein expression of MTA3 by immunohistochemistry assay and analyzed its association with glioma prognosis in 186 cases of patients. Results showed that MTA3 expression was decreased in glioma compared with that in normal brain (P < 0.05). In addition, tumors with high MTA3 expression were more likely to be of low WHO grade (P = 0.005) and reserve of body function (P = 0.014). Survival analysis showed that decreased MTA3 expression was independently associated with unfavorable overall survival of patients (P < 0.001). These results provide the first evidence that MTA3 expression was decreased in human glioma and negatively associated with prognosis of patients, suggesting that MTA3 may play a tumor suppressor role in glioma.

In vitro and in vivo study of a sodium chloride impregnated microarc oxidation-treated titanium implant surface.

Microarc oxidation (MAO) has been well-documented as an advantageous surface coating technique to improve implant osseointegration. Nevertheless, its strong susceptibility to bacteria critically impedes the development of MAO in clinical trials. Aimed at the efficient inhibition of bacterial invasion of MAO treated titanium (MAO-Ti) implants, a composite coating created by applying sodium chloride (NaCl) on a MAO-Ti implant surface layer was designed herein with the capacity to resist a broad spectrum of bacteria. In the present study, 10% NaCl was impregnated onto an optimized MAO-Ti implant to achieve a composite NaCl-MAO-Ti coating. First, Staphylococcus aureus (S. aureus), a frequently detected pathogen associated with peri-implantitis, was employed as an in vitro model. The visualization and quantification of S. aureus adhering to MAO-Ti and NaCl-MAO-Ti surfaces after incubation for 2, 4 and 24 h was described. Secondly, in an animal experiment, MAO-Ti and NaCl-MAO-Ti implants were placed into the tibia of male goats and these implants remained in situ for 9 weeks. The peri-implant soft tissue reactions, epithelial down growth and microorganisms separated from the inflammatory exudates were assessed during the whole process. The results of the in vitro study revealed that the NaCl-MAO-Ti implant surface significantly decreased the adhesion and multiplication of S. aureus compared to the untreated MAO-Ti. Moreover, the animal experiment established that the NaCl-MAO-Ti implants caused less peri-implant soft tissue infection and ultimately reduced the occurrence of peri-implantitis. Taken together, these data suggest that NaCl impregnated MAO-Ti implant products can effectively lower the risk of peri-implantitis and simultaneously preserve the osseointegration capacity of the MAO coating, which may help facilitate the application of NaCl-MAO-Ti implants in clinic trials.