In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca
ions to meet greater application demand, a strategy was designed to structure novel SA-based gels ...(named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl₂ and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si⁻O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.
The facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity on aluminum alloy surface by acid etching and polymer coating.
•Acid etching and polymer coating were used to ...prepare a superhydrophilic and superhydrophobic surface on aluminum alloy.•The facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity was readily realized by the simple method.•The superhydrophobic surfaces with a high water contact angle of 157̊ were obtained by the simple coating.
The transition from the hydrophilic surface to the superhydrophilic and superhydrophobic surface on aluminum alloy via hydrochloric acid etching and polymer coating was investigated by contact angle (CA) measurements and scanning electron microscope (SEM). The effects of etching and polymer coating on the surface were discussed. The results showed that a superhydrophilic surface was facilely obtained after acid etching for 20min and a superhydrophobic surface was readily fabricated by polypropylene (PP) coating after acid etching. When the etching time was 30min, the CA was up to 157̊. By contrast, two other polymers of polystyrene (PS) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after acid etching. The results showed that the CA was up to 159̊ by coating PP-g-MAH, while the CA was only 141̊ by coating PS. By modifying the surface with the silane coupling agent before PP coating, the durability and solvent resistance performance of the superhydrophobic surface was further improved. The micro–nano concave–convex structures of the superhydrophilic surface and the superhydrophobic surface were further confirmed by scanning electron microscope (SEM). Combined with the natural hydrophilicity of aluminum alloy, the rough micro–nano structures of the surface led to the superhydrophilicity of the aluminum alloy surface, while the rough surface structures led to the superhydrophobicity of the aluminum alloy surface by combination with the material of PP with the low surface free energy.
Objective
One of the major difficulties in spinal surgery is the injury of important tissues caused by tissue misclassification, which is the source of surgical complications. Accurate recognization ...of the tissues is the key to increase safety and effect as well as to reduce the complications of spinal surgery. The study aimed at tissue recognition in the spinal operation area based on electrical impedance and the boundaries of electrical impedance between cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus.
Methods
Two female white swines with body weight of 40 kg were used to expose cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus under general anesthesia and aseptic conditions. The electrical impedance of these tissues at 12 frequencies (in the range of 10–100 kHz) was measured by electrochemical analyzer with a specially designed probe, at 22.0–25.0°C and 50%–60% humidity. Two types of tissue recognition models ‐ one combines principal component analysis (PCA) and support vector machine (SVM) and the other combines combines SVM and ensemble learning ‐ were constructed, and the boundaries of electrical impedance of the five tissues at 12 frequencies of current were figured out. Linear correlation, two‐way ANOVA, and paired T‐test were conducted to analyze the relationship between the electrical impedance of different tissues at different frequencies.
Results
The results suggest that the differences of electrical impedance mainly came from tissue type (p < 0.0001), the electrical impedance of five kinds of tissue was statistically different from each other (p < 0.0001). The tissue recognition accuracy of the algorithm based on principal component analysis and support vector machine ranged from 83%–100%, and the overall accuracy was 95.83%. The classification accuracy of the algorithm based on support vector machine and ensemble learning was 100%, and the boundaries of electrical impedance of five tissues at various frequencies were calculated.
Conclusion
The electrical impedance of cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus had significant differences in 10–100 kHz frequency. The application of support vector machine realized the accurate tissue recognition in the spinal operation area based on electrical impedance, which is expected to be translated and applied to tissue recognition during spinal surgery.
The electrical impedance of cortical bone, cancellous bone, spinal cord, muscle, and nucleus pulposus were significantly different in the spinal operation area. SVM combined with PCA or ensemble learning can be used to accurately identify the tissue in the spinal operation area based on electrical impedance.
Amphiphilic ethyl cellulose (EC)-
g-poly(acrylic acid) (PAA) copolymers were synthesized by atom transfer radical polymerization (ATRP). Firstly, ethyl cellulose macro-initiators with the degree of ...the 2-bromoisobutyryl substitution of 0.04 and 0.25 synthesized by the esterification of the hydroxyl groups remained in EC macromolecular chains and the 2-bromoisobutyryl bromides. Secondly,
tert-butyl acrylate was polymerized by ATRP with the ethyl cellulose macro-initiator and EC-
g-P
tBA copolymers were prepared. Finally, the EC-
g-PAA copolymers were prepared by hydrolyzing
tert-butyl group of the EC-
g-P
tBA copolymers. The grafting copolymers were characterized by means of GPC,
1H NMR and FTIR spectroscopies. The molecular weight of graft copolymers increased during the polymerization and the polydispersity was low. A kinetic study showed that the polymerization was first-order. Meanwhile, EC-
g-PAA copolymers were self-assembled to micelles or particles with diameters of 5
nm and 100
nm in water (pH
=
10) when the concentration was 1.0
mg/ml.
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► Self-assembly behavior of cellulose-based dense graft copolymers. ► Backbone-collapsed intra- and inter-molecular self-assembly. ► Unimolecular micellar structure.
The self-assembly ...of cellulose-based amphiphilic dense grafting copolymer ethyl cellulose graft poly(acrylic acid) (EC-
g-PAA) in a selective solvent was measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Our aim is to realize the intra- or inter-molecular association by collapsing the backbone of dense grafting copolymers. The effects of grafting density, grafting length and solvent on the formation of the unimolecular or multimolecular micelles of EC-
g-PAA were discussed. It was shown that the self-association of the grafting copolymers could occur in the mixed solvents of THF and water. The shorter graft chain could induce the multimolecular micelles, while the longer graft chain could lead to the unimolecular micelles. The possible micellization mechanism was proposed from the aspect of chain conformation.
3D printing (3DP) is becoming a research and development focus in nanobiomaterials as it can quickly and accurately fabricate any desired 3D tissuemodel only if itssize is appropriate. The different ...material powders (with different dimensional scales) and the printing strategies are the most direct factors influencing 3DP quality. With the development of nanotechnologies, 3DP is adopted more frequently for its rapidness in fabrication and precision in geometry. The fabrication in micro/nanoscale may change the performance of biomaterials and devices because it can retain more anisotropy of biomaterials compared with the traditionally rapid prototyping techniques. Thus, the biosafety issue is especially concerned by many researchers and is investigated in performance and safety of biomaterials and devices. This paper investigates the performance of 3DP in fabrication of nanobiomaterials and devices so as to partially explain how 3DP influences the performance and safety of nanobiomaterials.
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In this paper, we address the problem of fully automatic labeling and segmentation of 3D vertebrae in arbitrary Field-Of-View (FOV) CT images. We propose a deep learning-based ...two-stage solution to tackle these two problems. More specifically, in the first stage, the challenging vertebra labeling problem is solved via a novel transformers-based 3D object detector that views automatic detection of vertebrae in arbitrary FOV CT scans as a one-to-one set prediction problem. The main components of the new method, called Spine-Transformers, are a one-to-one set based global loss that forces unique predictions and a light-weighted 3D transformer architecture equipped with a skip connection and learnable positional embeddings for encoder and decoder, respectively. We additionally propose an inscribed sphere-based object detector to replace the regular box-based object detector for a better handling of volume orientation variations. Our method reasons about the relationships of different levels of vertebrae and the global volume context to directly infer all vertebrae in parallel. In the second stage, the segmentation of the identified vertebrae and the refinement of the detected centers are then done by training one single multi-task encoder-decoder network for all vertebrae as the network does not need to identify which vertebra it is working on. The two tasks share a common encoder path but with different decoder paths. Comprehensive experiments are conducted on two public datasets and one in-house dataset. The experimental results demonstrate the efficacy of the present approach.
Cancer stem cell-like side population (SP) cells, which may be responsible for recurrence, tumor metastasis, and resistance to cancer therapy, have been identified and characterized in several types ...of cell lines from gastric cancer. However, there is no report on isolation of SP cells from human gastric cancer cell line HGC-27. This study aims to analyze the proportion of SP cells in HGC-27 cell line, differentiate SP from non-side population (NSP) cells, and determine whether the SP cells have certain biological properties of stem cells.
(1) HGC-27 suspension was prepared and stained with Hoechst33342 and PI for flow cytometric isolation of SP (2). Differences in proliferation and stemness-related gene expression profiles (CD133, CD44, OCT-4, MDR1, EpCAM, and ABCG2) between SP and NSP cells were detected by gastric formation assay and quantitative real-time PCR (3). Oncogenicity of SP and NSP cells was determined in nude mice in vivo.
(1) SP cells accounted for 0.1-1.0% of HGC-27 cells, and decreased to 0% after verapamil inhibition. Using flow cytometry, we sorted 7.5×10⁵ SP cells and most HGC-27 cells were NSP cells (2). Gastric formation assay and MTT demonstrated that there was a significant difference in proliferation between SP and NSP cells. Gene expression analysis showed that the expression of genes was significantly higher in SP cells (3). The oncogenicity experiment in nude mice revealed that 105 SP cells were able to form tumors, which demonstrated higher tumorigenicity than non-SP cells.
These results collectively suggested that SP cells from HGC-27 cell line have some cancer stem cell properties and could be used for studying the pathogenesis of gastric cancer, which may contribute to discovery of novel therapeutic targets.
Bone drilling is widely used in orthopedic surgery. Microcracks will be generated in bone drilling, which may cause fatigue damages and stress fractures. Fresh bovine cortical bones were drilled via ...vibrational and conventional ways. Drilling operations were performed by a dynamic material testing machine, which can provide the vibration while maintaining uniform feed motion. The drill site and bone debris were observed through scanning electron microscope (SEM). The experimental results showed that fewer and shorter micro-cracks were formed in vibrational drilling than those formed in conventional way. And the surface morphology of bone debris from two different drilling ways was also quite different. It is expected that vibrational drilling in orthopedic surgery operation could decrease the microdamage to the bone, which could lower the incidence of stress fracture and contribute to the postoperative recovery.
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