Anisotropic gypsum scaling of corrugated polyvinylidene fluoride hydrophobic membrane in direct contact membrane distillation

Membrane distillation (MD) technology has gained a lot of attention for treatment of geothermal brine, high salinity waste streams. However, mineral scaling remains a major challenge when treating complex high-salt brines. The development of surface-patterned superhydrophobic membranes is one of the core strategies to solve this problem. We prepared flat sheet membranes (F-PVDF) and hydrophobic membranes with micron-scale corrugated pattern (C-PVDF) using a phase separation method. Their scaling behavior was systematically evaluated using calcium sulfate solutions and the impact of the feed flow was innovatively investigated. Although C-PVDF shows higher contact angle and lower sliding angle than F-PVDF, the scaling resistance of C-PVDF in the perpendicular flow direction has worst scaling resistance. Although the nucleation barrier of the corrugated membrane is the same at both parallel and perpendicular flow directions based on the traditional thermodynamic nucleation theory, experimental observations show that the C-PVDF has the best scaling resistance in the parallel flow direction. A 3D computational fluid dynamics (CFD) model was used and the hydrodynamic state of the pattern membranes was assessed as a determinant of the scaling resistance. The corrugated membrane with parallel flow mode (flow direction in parallel to the corrugation ridge) induces higher fluid velocity within the channel, which mitigated the deposition of crystals. While in the perpendicular flow mode (flow direction in perpendicular to the corrugation ridge), the solutions confined in the corrugated grooves due to vortex shielding, which aggravates the scaling. These results shed light on the mechanism of scaling resistance of corrugated membranes from a hydrodynamic perspective and reveal the mechanism of anisotropy exhibited by corrugated membranes in MD.

LASER as a tool for surface modification of dental biomaterials: A review

In recent years, the application of lasers for modifying the surface topography of dental biomaterials has received increased attention. This review paper aims to provide an overview of the current status on the utilization of lasers as a potential tool for surface modification of dental biomaterials such as implants, ceramics, and other materials used for restorative purposes. A literature search was done for articles related to the use of lasers for surface modification of dental biomaterials in English language published between October 2000 and March 2023 in Scopus, Pubmed and web of science, and relevant articles were reviewed. Lasers have been mainly used for surface modification of implant materials (71%), especially titanium and its alloys, to promote osseointegration. In recent years, laser texturing has also emerged as a promising technique to reduce bacterial adhesion on titanium implant surfaces. Currently, lasers are being widely used for surface modifications to improve osseointegration and reduce peri-implant inflammation of ceramic implants and to enhance the retention of ceramic restorations to the tooth. The studies considered in this review seem to suggest laser texturing to be more proficient than the conventional methods of surface modification. Lasers can alter the surface characteristics of dental biomaterials by creating innovative surface patterns without significantly affecting their bulk properties. With advances in laser technology and availability of newer wavelengths and modes, laser as a tool for surface modification of dental biomaterials is a promising field, with excellent potential for future research.

An ionic/thermal-responsive agar/alginate wet-spun microfiber-shaped hydrogel combined with grooved/wrinkled surface patterns and multi-functions

A dual stimuli-responsive wet-spun microfiber-shaped hydrogel is prepared by injecting a hot blend of two stimuli biopolymers alginate (i.e., ionic-responsive) and agar (i.e., temperature-responsive) into a pre-cooling and metal cation containing coagulation bath. Experimental results indicate the fiber microstructure could be manipulated by the extrusion rate and cooling temperature, achieving an anisotropic shrinkage characteristic and novel grooved/wrinkled surface patterns. Importantly, the integration of metal cations (e.g., Ca²⁺and/or Zn²⁺) was confirmed to significantly improve the hydrogel mechanical properties (i.e., double networks) and enhanced blue fluorescent intensity as a typical metal-polymer complexation formed within the agar gel matrix. Moreover, the functionality-independent double networks enabled typical pH-shape memory and sustainable antibacterial properties have also been demonstrated. Therefore, combing the facile fabricating approach and multifunctionality, this study would advance the development of stimuli-responsive hydrogel microfiber for complex biomedical systems.

Image-enhanced endoscopy for real-time differentiation between hyperplastic and fundic gland polyps in the stomach

BACKGROUND

Fundic gland polyps (FGP) of stomach are benign, while some hyperplastic polyps (HP) may harbor dysplasia or malignancy. Conventional white light endoscopy (WLE) cannot reliably distinguish FGP from HP. We investigated the role of image-enhanced endoscopy in differentiating FGP from HP.

METHODS

Patients with gastric polyps were recruited prospectively. The characteristics of the polyps were assessed using WLE and magnification narrow band imaging (mNBI). The microsurface, intervening space (IS), and microvascular (V) features of polyps were evaluated on mNBI. The pattern characteristic of FGP and HP were determined. Histopathology of polyps was the gold standard for diagnosis. Finally, in the validation phase, five endoscopists applied the characteristic features identified in this study to predict the type of gastric polyp and their performance was assessed.

RESULTS

Forty-five patients with a total of 70 gastric polyps (HP-46, FGP-24) were included in this study. On mNBI, the pattern characteristic of HP included peripheral curved type of white structures forming large circular/villous loops (microsurface), enlarged intervening space, and microvessels appearing as dark patches in the intervening space (p<0.001 vs. FGP). These were noted in 95.7% HP. In contrast, 95.8% FGP had a pattern characterized by dotted/elliptical/tubular white structures (microsurface), normal width of intervening space, and microvessels surrounding the white structures in a network pattern. This IS-V pattern classification had an accuracy of >90% in the validation phase with intra-class correlation coefficient of 0.95. The accuracy of mNBI was higher than WLE (97.1% vs. 67%) in predicting the type of gastric polyp.

CONCLUSIONS

Image-enhanced endoscopy with mNBI (IS-V pattern) performs very well in differentiating HP from FGP.

Anisotropic scaffolds for peripheral nerve and spinal cord regeneration

The treatment of long-gap (>10 mm) peripheral nerve injury (PNI) and spinal cord injury (SCI) remains a continuous challenge due to limited native tissue regeneration capabilities. The current clinical strategy of using autografts for PNI suffers from a source shortage, while the pharmacological treatment for SCI presents dissatisfactory results. Tissue engineering, as an alternative, is a promising approach for regenerating peripheral nerves and spinal cords. Through providing a beneficial environment, a scaffold is the primary element in tissue engineering. In particular, scaffolds with anisotropic structures resembling the native extracellular matrix (ECM) can effectively guide neural outgrowth and reconnection. In this review, the anatomy of peripheral nerves and spinal cords, as well as current clinical treatments for PNI and SCI, is first summarized. An overview of the critical components in peripheral nerve and spinal cord tissue engineering and the current status of regeneration approaches are also discussed. Recent advances in the fabrication of anisotropic surface patterns, aligned fibrous substrates, and 3D hydrogel scaffolds, as well as their in vitro and in vivo effects are highlighted. Finally, we summarize potential mechanisms underlying the anisotropic architectures in orienting axonal and glial cell growth, along with their challenges and prospects.

Evaluation of blue laser endoscopy for detecting colorectal non-pedunculated adenoma

BACKGROUND AND STUDY AIMS

Non-pedunculated lesions are easily missed on endoscopy, and histopathological examination shows that some of these lesions are adenomas. Adenoma is a precursor of colorectal cancer, a common tumor of the digestive tract. This study was conducted to compare the detection efficacy of non-pedunculated lesions in the same patient under different modes of blue laser endoscopy and to determine whether the surface pattern of the sample was consistent with its histopathological results.

PATIENTS AND METHODS

A total of 91 patients with non-pedunculated lesions diagnosed at our hospital between April 2018 and March 2019 were included in this study. White light imaging (WLI), linked color imaging (LCI), and blue laser imaging (BLI) modes were used to record the location, number, and Hiroshima classification of the surface patterns of the non-pedunculated lesions. The lesions were removed by different endoscopic excision methods for histopathological examination; the histopathological results were compared with the surface patterns.

RESULTS

A total of 105, 198, and 223 lesions were detected using the WLI, BLI, and LCI modes, respectively. The Wilcoxon signed rank test revealed a significant difference in the number of lesions detected using each observation mode (p < 0.01). The non-pedunculated lesions were primarily located in the rectum and transverse colon, followed by the sigmoid, descending, and ascending colon. The efficacy of LCI and BLI modes was better than that of WLI mode for detecting the non-pedunculated lesions measuring < 5 mm in size (p < 0.05). The surface pattern was not detected by the WLI mode. The surface patterns detected using the LCI and BLI modes were primarily types A and B. Histopathological results of the non-pedunculated lesions included inflammatory polyp, hyperplastic polyp, tubular adenoma, and adenoma. Surface patterns could not be detected using the WLI mode. The McNemar's test revealed a significant difference between the WLI mode findings and the histopathological results (p < 0.01). No significant difference was observed between the histopathological results and the surface patterns detected using the LCI mode (kappa = 0.57); the agreement was poor. There was also no significant difference between the histopathological results and the surface patterns detected using the BLI mode (kappa test, p < 0.01; kappa = 0.88); hence, there was good agreement between the surface patterns detected using the BLI mode and the histopathological results.

CONCLUSION

The detection rate of colorectal non-pedunculated lesions may be improved using blue laser endoscopy. Non-pedunculated colorectal adenomas could be identified more accurately using the BLI mode, which might improve the adenoma detection rate, thus indicating that BLI is a feasible option in the practical settings.

Modeling and application of anisotropic hyperelasticity of PDMS polymers with surface patterns obtained by additive manufacturing technology

Polydimethylsiloxane (PDMS) polymer has been widely used in the biomedical fields because of its bio-compatibility, being used as sensors, medical equipment and tissue implants. The present study aims to synthesize and characterize micro lane-type surface patterns of PDMS polymers and evaluate their effects on mechanical properties for various applications in the bio-engineering field. Fabrication of surface patterns is achieved using fused filament fabrication in additive manufacturing, and the mechanical properties of the polymer specimens with the surface patterns are measured using tensile test. The surface patterns are rotated at different angles and changed into different shapes to change the anisotropic material properties of the PDMS specimens. This is achieved by changing the raster angles and modifying the fused filament paths during the additive manufacturing process. In addition, the application of the printed pattern to medical soft robot is presented. Owing to the anisotropic material properties, in-plane and out-of-plane actuation can be realized by attaching polymer patches with different lane-type surface patterns. The results of this study support the implementation of additive manufacturing for the rapid manufacture of scalable structures with anisotropic material properties for various applications.

Hydrodynamics and surface properties influence biofilm proliferation

A biofilm is an interface-associated colloidal dispersion of bacterial cells and excreted polymers in which microorganisms find protection from their environment. Successful colonization of a surface by a bacterial community is typically a detriment to human health and property. Insight into the biofilm life-cycle provides clues on how their proliferation can be suppressed. In this review, we follow a cell through the cycle of attachment, growth, and departure from a colony. Among the abundance of factors that guide the three phases, we focus on hydrodynamics and stratum properties due to the synergistic effect such properties have on bacteria rejection and removal. Cell motion, whether facilitated by the environment via medium flow or self-actuated by use of an appendage, drastically improves the survivability of a bacterium. Once in the vicinity of a stratum, a single cell is exposed to near-surface interactions, such as van der Waals, electrostatic and specific interactions, similarly to any other colloidal particle. The success of the attachment and the potential for detachment is heavily influenced by surface properties such as material type and topography. The growth of the colony is similarly guided by mainstream flow and the convective transport throughout the biofilm. Beyond the growth phase, hydrodynamic traction forces on a biofilm can elicit strongly non-linear viscoelastic responses from the biofilm soft matter. As the colony exhausts the means of survival at a particular location, a set of trigger signals activates mechanisms of bacterial release, a life-cycle phase also facilitated by fluid flow. A review of biofilm-relevant hydrodynamics and startum properties provides insight into future research avenues.

Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface

Scaling in membrane distillation (MD) is a key issue in desalination of concentrated saline water, where the interface property between the membrane and the feed become critical. In this paper, a slippery mechanism was explored as an innovative concept to understand the scaling behavior in membrane distillation for a soluble salt, NaCl. The investigation was based on a novel design of a superhydrophobic polyvinylidene fluoride (PVDF) membrane with micro-pillar arrays (MP-PVDF) using a micromolding phase separation (μPS) method. The membrane showed a contact angle of 166.0 ± 2.3° and the sliding angle of 15.8 ± 3.3°. After CF₄ plasma treatment, the resultant membrane (CF₄-MP-PVDF) showed a reduced sliding angle of 3.0°. In direct contact membrane distillation (DCMD), the CF₄-MP-PVDF membrane illustrated excellent anti-scaling in concentrating saturated NaCl feed. Characterization of the used membranes showed that aggregation of NaCl crystals occurred on the control PVDF and MP-PVDF membranes, but not on the CF₄-MP-PVDF membrane. To understand this phenomenon, a "slippery" theory was introduced and correlated the sliding angle to the slippery surface of CF₄-MP-PVDF and its anti-scaling property. This work proposed a well-defined physical and theoretical platform for investigating scaling problems in membrane distillation and beyond.

Microfluidic synthesis and on-chip enrichment application of two-dimensional hollow sandwich-like mesoporous silica nanosheet with water ripple-like surface

The merits of microfluidics bring new opportunities for engineering of nanomaterials with well controlled chemical, physical and biological properties for a variety of applications. Herein, using a two-run spiral-shaped microfluidic device, we first develop a facile and straightforward flow synthesis strategy to create two-dimensional mesoporous silica nanosheet (MSN). Such MSN exhibits typical hollow sandwich-like bilayer and unique water ripple-like wrinkle surface, which greatly increase the particulate accessibility for mass transfer. The enhanced on-chip enrichment performance of MSN is further confirmed toward different substrates (dye, protein, drug). These findings not only shed new light on microfluidics-enabled chemicals engineering, but also open up numerous new possibilities by microfluidics in adsorption, separation, and biomedical fields.

Prediction of colorectal tumor grade and invasion depth through narrow-band imaging scoring

AIM

To determine the usefulness of assigning narrow-band imaging (NBI) scores for predicting tumor grade and invasion depth in colorectal tumors.

METHODS

A total of 161 colorectal lesions were analyzed from 138 patients who underwent endoscopic or surgical resection after conventional colonoscopy and magnifying endoscopy with NBI. The relationships between the surface and vascular patterns of the lesions, as visualized with NBI, and the tumor grade and depth of submucosa (SM) invasion were determined histopathologically. Scores were assigned to distinct features of the surface microstructures of tubular and papillary-type lesions. Using a multivariate analysis, a model was developed for predicting the tumor grade and depth of invasion based on NBI-finding scores.

RESULTS

NBI findings that correlated with a high tumor grade were associated with the “regular/irregular” (P < 0.0001) surface patterns and the “avascular area” pattern (P = 0.0600). The vascular patterns of “disrupted vessels” (P = 0.0714) and “thick vessels” (P = 0.0133) but none of the surface patterns were associated with a depth of invasion of ≥ 1000 μm. In our model, a total NBI-finding score ≥ 1 was indicative of a high tumor grade (sensitivity: 0.97; specificity: 0.24), and a total NBI-finding score ≥ 9 (sensitivity: 0.56; specificity: 1.0) was predictive of a SM invasion depth ≥ 1000 μm. Scores less than these cutoff values signified adenomas and a SM invasion depth < 1000 μm, respectively. Associations were also noted between selected NBI findings and tumor tissue architecture and histopathology.

CONCLUSION

Our multivariate statistical model for predicting tumor grades and invasion depths from NBI-finding scores may help standardize the diagnosis of colorectal lesions and inform therapeutic strategies.

Surface pattern by nanoimprint for membrane fouling mitigation: Design, performance and mechanisms

Imparting water treatment membrane with surface pattern by nanoimprint offered a novel approach to fouling resistance. We employed nanoimprint to fabricate line-shape nanostructure on membrane distillation (MD) membrane surface. Patterned MD membrane exhibited strong antifouling property to Bovine Serum Albumin (BSA) protein during MD separation. Water flux decline and protein deposition were substantially minimized on the patterned MD membrane in comparison with the pristine one. Such lower fouling propensity on the patterned MD membrane was mainly driven by the weak hydrophobic interaction between BSA protein and patterned MD membrane surface. Weaker adhesion force mapping of the patterned MD membrane was quantified. Representative force-distance curve of pristine MD membrane showed a strong attractive depletion force comparing with that of patterned one. The simple, chemical-free, and scalable nanofabrication approach enables varying designs on membrane surface for special membrane properties.

A Surface Pattern on MALDI Steel Plate for One-Step In-Situ Self-Desalting and Enrichment of Peptides/Proteins

We report a novel strategy to achieve simultaneous one-step in-situ self-desalting and enrichment (OISE) of peptides/proteins on a facilely fabricated patterned MALDI steel plate with a circular paraffin-steel-polystyrene structure. The OISE plate could efficiently segregate salts from both analytes and matrices while retaining both analyte and matrix concentrate, and facilitating them to form homogeneous co-crystals on the centrally located polystyrene pattern. With the OISE plate, high quality and reproducible spectra could be obtained for low abundance peptides even in the presence of high salt concentrations (200 mM NH₄HCO₃, 1 M NaCl, or 400 mM urea). Using this strategy, a significant sensitivity enhancement was gained over traditional MALDI plate. The practical utility of this method was further demonstrated by the successful profiling of BSA digests and human serum. Graphical Abstract ᅟ.

Surface patterned pH-sensitive fluorescence using β-cyclodextrin functionalized poly(ethylene glycol)

This paper reports the development of a pH-responsive molecular pattern that shows specific and selective affinity for particular host-guest interactions, and its use as a pH fluorescent sensor. The pH-responsive boronate ester is formed via interactions between the diol group of β-cyclodextrin (CD) and phenylboronic acid of poly(ethylene glycol), and is strategically designed to allow reversible formation of a molecular lining pattern. Printing on a versatile substrate provides a method to monitor the positioning of different molecules by using a pH-responsive boronate ester, allowing specific host-guest interactions on any surface. Confocal laser scanning microscopy, fluorescence spectroscopy, and (1)H NMR results indicate that the assembled CD monolayer can be removed by washing with an acidic pH buffer, demonstrating the presence of a boronate ester connective bridge, which is acid labile. Therefore, visualization of the pH-responsive fluorescence sensor using a rhodamine-CD complex allows straightforward discrimination between different molecules on any substrate, thus facilitating application of this sensor in clinical diagnostics and environmental monitoring.

Guiding the behaviors of human umbilical vein endothelial cells with patterned silk fibroin films

Silk fibroin is an ideal blood vessel substitute due to its advantageous qualities including variable size, good suture retention, low thrombogenicity, non-toxicity, non-immunogenicity, biocompatibility, and controllable biodegradation. In this study, silk fibroin films with a variety of surface patterns (e.g. square wells, round wells plus square pillars, square pillars, and gratings) were prepared for in vitro characterization of human umbilical vein endothelial cell's (HUVEC) response. The affects of biomimetic length-scale topographic cues on the cell orientation/elongation, proliferation, and cell-substrate interactions have been investigated. The density of cells is significantly decreased in response to the grating patterns (70±3nm depth, 600±8nm pitch) and the square pillars (333±42nm gap). Most notably, we observed the contact guidance response of filopodia of cells cultured on the surface of round wells plus square pillars. Overall, our data demonstrates that the patterned silk fibroin films have an impact on the behaviors of human umbilical vein endothelial cells.