Preparation of Alginate-Based Biomaterials and Their Applications in Biomedicine.

Alginates are naturally occurring polysaccharides extracted from brown marine algae and bacteria. Being biocompatible, biodegradable, non-toxic and easy to gel, alginates can be processed into various forms, such as hydrogels, microspheres, fibers and sponges, and have been widely applied in biomedical field. The present review provides an overview of the properties and processing methods of alginates, as well as their applications in wound healing, tissue repair and drug delivery in recent years.

Preventing nickel-titanium rotary instrument from breakage by continuous irrigation with different fluids during root canal preparation.

ABSTRACT: To study the effect of continuous irrigation of rotating nickel-titanium instrument with several common clinical fluids on the diameter, breaking length and breaking position of nickel-titanium instrument, so as to provide some reference and theoretical basis for clinical operation and instrument improvement.A standardized curved root canal model was established, and ProTaper Universal (PTU) F1 instrument was selected for root canal preparation. The nickel-titanium F1 instrument was flushed with distilled water, 0.9% NaCl, 0.2% chlorhexidine, 1% sodium hypochlorite and 5% sodium hypochlorite, and the diameter, length and position of the instrument before and after breakage were recorded.Only 5% sodium hypochlorite influenced the diameter of 6 mm marker points under different irrigation conditions (P < .05). There was no statistical difference in the length of broken instruments among all the groups, and torsional deformation mainly occurred at the end of broken instruments. The broken positions of instruments in all the groups were located at the bending segment of the root canal. The breaking frequency of the 5% sodium hypochlorite group was the highest in the area 3-5.5 mm away from apical foramen, while the other 4 groups had the highest breaking frequency in the area 0 to 1.5 mm away from apical foramen.External irrigation with different fluids did not influence the breaking length of instruments. The closer to the apical foramen was, the higher the breaking frequency of instruments was. However, only 5% sodium hypochlorite can affect the diameter of rotary nickel-titanium instruments, and may lead to early breakage of the instrument, indicating that the use of disinfectants, except 5% sodium hypochlorite, cannot reduce breakage resistance of nickel-titanium instrument compared with distilled water flushing. Furthermore, 5% hypochlorite could not be recommended for irrigation in clinical practice.

Hematite Nanoparticles from Unexpected Reaction of Ferrihydrite with Concentrated Acids for Biomedical Applications.

The development of synthetic ways to fabricate nanosized materials with a well-defined shape, narrow-sized distribution, and high stability is of great importance to a rapidly developing area of nanotechnology. Here, we report an unusual reaction between amorphous two-line ferrihydrite and concentrated sulfuric or other mineral and organic acids. Instead of the expected dissolution, we observed the formation of new narrow-distributed brick-red nanoparticles (NPs) of hematite. Different acids produce similar nanoparticles according to scanning (SEM) and transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The reaction demonstrates new possibilities for the synthesis of acid-resistant iron oxide nanoparticles and shows a novel pathway for the reaction of iron hydroxide with concentrated acids. The biomedical potential of the fabricated nanoparticles is demonstrated by the functionalization of the particles with polymers, fluorescent labels, and antibodies. Three different applications are demonstrated: i) specific targeting of the red blood cells, e.g., for red blood cell (RBC)-hitchhiking; ii) cancer cell targeting in vitro; iii) infrared ex vivo bioimaging. This novel synthesis route may be useful for the development of iron oxide materials for such specificity-demanding applications such as nanosensors, imaging, and therapy.

Latest Advances on Bacterial Cellulose-Based Materials for Wound Healing, Delivery Systems, and Tissue Engineering.

Bacterial cellulose (BC) is a nanocellulose form produced by some nonpathogenic bacteria. BC presents unique physical, chemical, and biological properties that make it a very versatile material and has found application in several fields, namely in food industry, cosmetics, and biomedicine. This review overviews the latest state-of-the-art usage of BC on three important areas of the biomedical field, namely delivery systems, wound dressing and healing materials, and tissue engineering for regenerative medicine. BC will be reviewed as a promising biopolymer for the design and development of innovative materials for the mentioned applications. Overall, BC is shown to be an effective and versatile carrier for delivery systems, a safe and multicustomizable patch or graft for wound dressing and healing applications, and a material that can be further tuned to better adjust for each tissue engineering application, by using different methods.

Recent Progress in Polyhydroxyalkanoates-Based Copolymers for Biomedical Applications.

In recent years, naturally biodegradable polyhydroxyalkanoate (PHA) monopolymers have become focus of public attentions due to their good biocompatibility. However, due to its poor mechanical properties, high production costs, and limited functionality, its applications in materials, energy, and biomedical applications are greatly limited. In recent years, researchers have found that PHA copolymers have better thermal properties, mechanical processability, and physicochemical properties relative to their homopolymers. This review summarizes the synthesis of PHA copolymers by the latest biosynthetic and chemical modification methods. The modified PHA copolymer could greatly reduce the production cost with elevated mechanical or physicochemical properties, which can further meet the practical needs of various fields. This review further summarizes the broad applications of modified PHA copolymers in biomedical applications, which might shred lights on their commercial applications.

Silylation of bacterial cellulose to design membranes with intrinsic anti-bacterial properties.

In this work, we report a convenient method of grafting non-leachable bioactive amine functions onto the surface of bacterial cellulose (BC) nanofibrils, via a simple silylation treatment in water. Two different silylation protocols, involving different solvents and post-treatments were envisaged and compared, using 3-aminopropyl-trimethoxysilane (APS) and (2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPS) as silylating agents. In aqueous and controlled conditions, water-leaching resistant amino functions could be successfully introduced into BC, via a simple freeze-drying process. The silylated material remained highly porous, hygroscopic and displayed sufficient thermal stability to support the sterilization treatments generally required in medical applications. The impact of the silylation treatment on the intrinsic anti-bacterial properties of BC was investigated against the growth of Escherichia coli and Staphylococcus aureus. The results obtained after the in vitro studies revealed a significant growth reduction of S. aureus within the material.

Challenges in creating dissectible anatomical 3D prints for surgical teaching.

Three-dimensional (3D) printing, or additive manufacturing, is now a widely used tool in pre-operative planning, surgical teaching and simulator training. However, 3D printing technology that produces models with accurate haptic feedback, biomechanics and visuals for the training surgeon is not currently available. Challenges and opportunities in creating such surgical models will be discussed in this review paper. Surgery requires proper tissue handling as well as knowledge of relevant anatomy. To prepare doctors properly, training models need to take into account the biomechanical properties of the anatomical structures that will be manipulated in any given operation. This review summarises and evaluates the current biomechanical literature as it relates to human tissues and correlates the impact of this knowledge on developing high fidelity 3D printed surgical training models. We conclude that, currently, a printer technology has not yet been developed which can replicate many of the critical qualities of human tissue. Advances in 3D printing technology will be required to allow the printing of multi-material products to achieve the mechanical properties required.

Advanced electronic skin devices for healthcare applications.

Electronic skin, a kind of flexible electronic device and system inspired by human skin, has emerged as a promising candidate for wearable personal healthcare applications. Wearable electronic devices with skin-like properties will provide platforms for continuous and real-time monitoring of human physiological signals such as tissue pressure, body motion, temperature, metabolites, electrolyte balance, and disease-related biomarkers. Transdermal drug delivery devices can also be integrated into electronic skin to enhance its non-invasive, real-time dynamic therapy functions. This review summarizes the recent progress in electronic skin devices for applications in human health monitoring and therapy systems as well as several potential mass production technologies such as inkjet printing and 3D printing. The opportunities and challenges in broadening the applications of electronic skin devices in practical healthcare are also discussed.

Periodontal regenerative effect of enamel matrix derivative in diabetes.

The present study aimed to investigate the periodontal regenerative effect of enamel matrix derivative (EMD) in diabetes. Thirty-six rats were assigned to streptozotocin-induced diabetes or control (non-diabetic) groups. Three-wall intrabony defects were surgically generated in the bilateral maxilla molar, followed by application of EMD or saline. Primary wound closure and defect fill were evaluated via histomorphological analysis and micro-computed tomography. mRNA expression levels of inflammatory and angiogenic factors in the defects were quantified via real-time polymerase chain reaction. Gingival fibroblasts were isolated from control animals and cultured in high-glucose (HG) or control medium. The effects of EMD on insulin resistance and PI3K/Akt/VEGF signaling were evaluated. The achievement rate of primary closure and the parameters of defect fill were significantly higher at EMD-treated site than at EMD-untreated sites in both diabetic and non-diabetic rats, although defect fill in the diabetic groups was significantly lower in the control groups on two-way repeated-measures analysis of variance (for both, p<0.05). Newly formed bone and cementum were significantly increased at EMD-treated sites in diabetic rats than at EMD-untreated sites in control rats (for both, p<0.05). Vegf was significantly upregulated at EMD-treated sites in both diabetic and non-diabetic rats (for both, p<0.05). In vitro, insulin or EMD-induced Akt phosphorylation was significantly lower in cells cultured in HG medium (p<0.05). EMD-mediated Vegf upregulation was suppressed by the Akt inhibitor wortmannin, although the effect was significantly lower in HG medium (p<0.01). In conclusion, EMD might promote periodontal tissue regeneration via Akt/VEGF signaling, even in a diabetic condition.

Nanostructured biomedical selenium at the biological interface (Review).

This paper critically reviews the current evidence of research in biomedical applications of selenium nanoparticles (SeNPs) and their effects at cellular and tissue levels. In recent years, interest in SeNPs as a natural trace element nanomaterial for nanomedicine has resulted in a number of studies evaluating their bioactivities, such as anticancer, antimicrobial, and antioxidant properties. Significant data have been generated to demonstrate the effectiveness of SeNPs alone or in combination with other reagents. Their activities are demonstrated through in vitro and in vivo experimentation; yet, the levels of efficacy need to be improved, particularly when compared with those of pharmaceutical drugs (such as antibiotics and cytotoxic chemotherapeutic drugs). However, promising evidence suggests decreased toxicity when using SeNPs, and more importantly their ability to perform as an interfacing biomaterial with cells and tissues. SeNPs have demonstrated unique antibacterial properties: they inhibit bacterial adhesion, growth, and/or quorum sensing and as a result prevent biofilm formation on medical devices, to name a few. Therefore, as with other nanomaterials, SeNPs warrant further study as part of the biomaterial-based therapeutic toolkit as an alternative to traditional pharmaceutical agents. This paper will provide a succinct review of recent studies on SeNPs to critically assess the findings in the light of effectiveness, particularly highlighting the roles of the cellular interface. Finally, an outlook of the potential of SeNPs will be presented to highlight the need for more intensive studies of material stability, mechanistic understanding at subcellular levels, and investigations into their combinational and/or synergistic effects with other bioactive reagents including pharmaceutical drugs.

Changes in growth plate extracellular matrix composition and biomechanics following in vitro static versus dynamic mechanical modulation.

The objective of this study was to investigate the effects of mechanical modulation parameters on structural proteins biocomposition and mechanical properties of the growth plate. Establishing these parameters is a crucial step in the development of fusionless treatment of scoliosis. In this study, ulna explants from 4-weeks-old (pubertal) swines were used. The biocomposition was characterized using biochemical content evaluation and immunohistochemistry. Mechanical properties were characterized by fitting the data of the stress relaxation curves using a fibril reinforced biphasic model. For the mechanical loading, one static modulation condition and three different dynamic modulation conditions, with similar average stress but different amplitude and frequency values, were performed using a bioreactor. Results showed that static loading triggers a decrease in proteoglycan content and type X collagen in specific zones of the growth plate. These changes can be associated with the observed decrement of permeability in the static group. None of the three conditions evaluated for dynamic modulation affected the growth plate biocomposition and biomechanical responses. Results of this study provides an improved understanding of growth plate responses to mechanical environment, which will be useful in finding the optimal and non-damaging parameters for fusionless treatments based on the mechanical modulation of bone growth.

Modern Theories of Pelvic Floor Support : A Topical Review of Modern Studies on Structural and Functional Pelvic Floor Support from Medical Imaging, Computational Modeling, and Electromyographic Perspectives.

PURPOSE OF REVIEW: Weakened pelvic floor support is believed to be the main cause of various pelvic floor disorders. Modern theories of pelvic floor support stress on the structural and functional integrity of multiple structures and their interplay to maintain normal pelvic floor functions. Connective tissues provide passive pelvic floor support while pelvic floor muscles provide active support through voluntary contraction. Advanced modern medical technologies allow us to comprehensively and thoroughly evaluate the interaction of supporting structures and assess both active and passive support functions. The pathophysiology of various pelvic floor disorders associated with pelvic floor weakness is now under scrutiny from the combination of (1) morphological, (2) dynamic (through computational modeling), and (3) neurophysiological perspectives. This topical review aims to update newly emerged studies assessing pelvic floor support function among these three categories. RECENT FINDINGS: A literature search was performed with emphasis on (1) medical imaging studies that assess pelvic floor muscle architecture, (2) subject-specific computational modeling studies that address new topics such as modeling muscle contractions, and (3) pelvic floor neurophysiology studies that report novel devices or findings such as high-density surface electromyography techniques. We found that recent computational modeling studies are featured with more realistic soft tissue constitutive models (e.g., active muscle contraction) as well as an increasing interest in simulating surgical interventions (e.g., artificial sphincter). Diffusion tensor imaging provides a useful non-invasive tool to characterize pelvic floor muscles at the microstructural level, which can be potentially used to improve the accuracy of the simulation of muscle contraction. Studies using high-density surface electromyography anal and vaginal probes on large patient cohorts have been recently reported. Influences of vaginal delivery on the distribution of innervation zones of pelvic floor muscles are clarified, providing useful guidance for a better protection of women during delivery. We are now in a period of transition to advanced diagnostic and predictive pelvic floor medicine. Our findings highlight the application of diffusion tensor imaging, computational models with consideration of active pelvic floor muscle contraction, high-density surface electromyography, and their potential integration, as tools to push the boundary of our knowledge in pelvic floor support and better shape current clinical practice.

Decrease of insoluble glucan formation in Streptococcus mutans by co-cultivation with Enterococcus faecium T7 and glucanase addition.

OBJECTIVES: To develop preventive canine oral health bio-materials consisting of probiotics and glucanase to reduce insoluble glucan and volatile sulfur compound formation. RESULTS: Co-cultivation of Enterococcus faecium T7 with Streptococcus mutans at inoculation ratio of 3:1 (v/v) resulted in 25% reduction in the growth of Streptococcus mutans. Amounts of soluble and insoluble glucans produced by S. mutans were decreased to 70 and 55%, respectively. Insoluble glucan was decreased from 0.6 µg/ml in S. mutans culture to 0.03 µg/ml in S. mutans co-cultivated with E. faecium T7 in the presence of Lipomyces starkeyi glucanase. Volatile sulfur compound, a main component of halitosis produced by Fusobacteria nucleatum, was decreased by co-cultivating F. nucleatum with E. faecium. CONCLUSION: E. faecium and glucanase can be combined as potentially active ingredients of oral care products for pets by reducing plaque-forming bacteria growth and their by-products that cause cavity and periodontal disease.

Gait training for chronic ankle instability improves neuromechanics during walking.

A novel gait-training device has been shown to improve gait patterns while patients with chronic ankle instability (CAI) are using the device and our current objective was to analyze the effect of structured gait training with the device on plantar pressure and surface electromyography (sEMG) following repeated gait training sessions. Sixteen CAI patients participated. Plantar pressure and sEMG were collected simultaneously during walking pre- and post-gait training. Plantar pressure (pressure time integral, peak pressure, time to peak pressure, contact area, contact time, and center of pressure trajectory) of the entire foot and nine specific regions of the foot were recorded concurrently with sEMG root mean square amplitudes from the anterior tibialis, peroneus longus, medial gastrocnemius, and gluteus medius. Five gait training sessions were performed with each session lasting approximately 15 min. Pre- and post-gait training self-reported function, plantar pressure, and sEMG were compared using paired t-tests with a priori level of significance of p ≤ 0.05. Gait training improved self-reported function (FAAM-Sport scale: Pre = 75.1 ± 7.1%, Post = 85.7 ± 12.2%, p < 0.001) and caused a medial shift in the COP from 10% of stance through toe-off (p < 0.05 for all analyses). The medial shift in COP was driven by concurrent increases in peroneus longus muscle activity from 21% to 60% and 81% to 90% of stance (p < 0.05 for all analyses). There was a corresponding reduction in gluteus medius muscle activity during 71-100% of stance (p < 0.05 for all analyses). Overall, gait training with a device that targets the peroneus longus and gluteus medius throughout the gait cycle improved gait patterns in CAI patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:515-524, 2018.

Irregular Implant Design Decreases Periimplant Stress and Strain Under Oblique Loading.

OBJECTIVES: To investigate whether a different implant geometry with the same potential contact surface area (PCSA) affects the principal stress and strains in bone. MATERIAL AND METHODS: Three-dimensional finite-element models were created with a single endosseous implant embedded in bone. The irregular (IR) dental root-analog implant and regular (R) cylindrical implant with the same PCSA 350 mm were modeled, keeping the size of the thinnest implant wall 0.8 mm, and the thinnest bone wall 1 mm. The regular or irregular abutments were either 4.5 mm lower than the platform of the implants or 5 mm higher than the platform of the implants, both with the taper 1.44°. A 100 N vertical or 100 N vertical/50 N horizontal occlusal loading was applied. The biomechanical behaviors of periimplant bone were recorded. RESULTS: The IR implant design experienced lower periimplant stress and strain under oblique loading than that of R implant design. In the IR implant design, comparable stress in bone, implant, and abutment were found under 100 N vertical loading or 100 N vertical/50 N horizontal loading. In the R implant design, much higher stress in bone, implant, and abutment were found under 100 N vertical/50 N horizontal loading than that under 100 N vertical loading. CONCLUSION: Irregular dental root-analog implant is a biomechanically favorable design principle for decreasing periimplant stress and strain under oblique loading.

Influence of acid treatment on surface properties and in vivo performance of Ti6Al4V alloy for biomedical applications.

The purpose of this work was to investigate the influence of acid treatment on the surface properties and in vivo performance of titanium grade 5 (Ti6Al4V) alloy. Mini-implants with surface treatment were inserted into New Zealand rabbit tibia for 1, 4 and 8 weeks. SEM analysis showed intercommunicated micropores in acid treated samples. AFM showed micron and sub-micron roughness. The thickness of the titanium oxide layer increased with surface treatment, with a significant reduction of Al and V concentration. Acid treated implant removal torque was larger than without treatment. The implants/bone interface of acid treated implants showed dense adhered Ca/P particles with spreading osteoblasts after 4 weeks and newly formed bone trabeculae after 8 weeks. Analysis of rabbit blood that received treated implant showed lower Al and V contents at all times. Acid treatment improved surface morphology and mechanical stability, which allowed initial events of osseointegration, while Al-V ion release was reduced. GRAPHICAL ABTSRACT.

Minimal Device Encrustation on Vesair Intravesical Balloons in the Treatment of Stress Urinary Incontinence: Analysis of Balloons Removed from Women in the SOLECT Trial.

INTRODUCTION: Encrustation of urinary biomaterials is common; however, the incidence of surface deposition on the Vesair® intravesical pressure-attenuation balloon has not been previously reported. The purpose of this analysis is to determine the incidence and potential risk factors for encrustation of the Vesair intravesical balloon. METHODS: The SOLECT trial is a prospective randomized controlled trial conducted at several European centers to evaluate the safety and efficacy of the Vesair balloon for the treatment of female stress urinary incontinence (SUI). Women included in the study demonstrated SUI symptoms for more than 12 months without complicating factors, such as history of recurrent urinary tract infections or nephrolithiasis. All balloons removed from women enrolled in the SOLECT trial were analyzed for surface characteristics and encrustation. Surface deposition severity was quantified and composition analyzed with infrared spectroscopy and scanning electron microscopy. Incidence of surface deposition was tabulated and risk factors analyzed. RESULTS: One hundred and five balloons removed from 75 women were included in this analysis. Measurable stone deposition of less than 1.5 mm was found on four balloons (3.8%), surface granules were noted on 42 (40.0%), surface film on 11 (10.5%), and both granules and film on two (1.9%). Analysis identified calcium oxalate both in measurable encrustation deposits as well as those with surface granulation. Pooled analysis found that dwell time was a risk factor for calcium deposition. CONCLUSION: The rate of encrustation on the Vesair intravesical balloon is low and does not appear to increase the rate of adverse outcomes or reduce clinical efficacy. FUNDING: Solace Therapeutics, Inc.

Unnoticed aspiration of palate plate impression material in a neonate: Diagnosis, therapy, outcome.

A 7 week old infant was admitted with respiratory failure. Chest X-ray showed an atelectatic right upper lobe, herniation of right middle and lower lobe into the left thorax, and compression-atelectasis of the left lung. Thoracic CT showed complete occlusion of the right superior bronchus with a radiopaque foreign material. Six weeks prior, an impression for a palate plate using polyvinylsiloxane was taken. The material was removed with a rigid endoscopy, in readiness of extracorporeal oxygenation in case of tracheal obstruction or bronchial rupture. After 4 months of follow-up a hyper reactive airway with recurrent upper and lower airway infections remains.

Biomechanical behavior of endodontically treated premolars using different preparation designs and CAD/CAM materials.

OBJECTIVES: To evaluate the effect of restoration design ('2.5-mm deep endocrown', '5-mm deep endocrown' or '5-mm deep post&crown') and CAD/CAM material type (composite or lithium disilicate glass-ceramic) on the load-to-failure of endodontically treated premolars in absence of any ferrule. METHODS: The crowns of 48 single-rooted premolars were cut and the roots were endodontically treated. Teeth were randomly divided into six groups (n=8); teeth in each group were restored using one of the two tested materials with standardized CAD/CAM fabricated endocrowns (with either 2.5-mm or 5-mm deep intra-radicular extension) or conventional crowns (5-mm deep post&crown). After cementation using luting composite, the specimens were immersed in distilled water and subjected to 1,200,000 chewing cycles with a load of 50N applied parallel to the long axis of the tooth (0°). After cyclic loading, a compressive load was applied at 45° to the tooth's long axis using a universal testing machine until failure. Load-to-failure was recorded (N) and the specimens were examined under a stereomicroscope with 3.5x magnification to determine the mode of failure. RESULTS: All specimens survived the 1,200,000 chewing cycles. A significant interaction between restoration design and CAD/CAM material was found using two-way ANOVA. In the '2.5-mm deep endocrown' groups, the composite achieved a significantly higher load-to-failure than the lithium disilicate glass-ceramic, while no differences between materials were found in the '5-mm deep endocrown' and '5-mm deep post&crown' groups. More unfavorable failures (root fractures) were observed for higher load-to-failure values. CONCLUSIONS: Only following a '2.5-mm deep endocrown' design, composite appeared more favorable than lithium disilicate glass-ceramic as crown material; this may be explained by their difference in elastic modulus. CLINICAL SIGNIFICANCE: Shallow endocrown preparations on premolars present less surface for adhesive luting and a difference in crown material becomes apparent in terms of load-to-failure. The use of a more flexible composite crown material appeared then a better option.