Materials In Biomedical Engineering Research Articles

Near‐Infrared Responsive Nanomaterials for the Regulation of Ion Channel Function

AbstractIon channels are responsible for the propagation and integration of electrical signals in physiological processes. Overactivation or dysfunction of ion channel plays an important role in physiological and pathological processes and is an important research object for disease treatment. With the widespread application of optical technologies of near infrared (NIR) light responsive materials, the precise regulation of biological processes through optical control, featuring noninvasive, remote control, and high flexibility, has penetrated the physiological processes. In recent years, an increasing number of light‐stimulated materials have been developed and utilized, with stable properties, easy modification, and sensitive response, enabling precise control of biological processes at the forefront of biomedical research. This review summarizes NIR responsive materials in ion channel regulation and elucidates their action mechanism in regulating ion channel‐related diseases. It is hoped that this review can provide foundation of research for future light‐stimulated materials, promote the application of light‐stimulated materials in biomedical engineering, and be useful for clinical disease treatment.

On the strain stiffening and nanofiber orientation of physically crosslinked nanocellulose hydrogels

Nanocellulose hydrogels that consist of physically crosslinked nanofibrous networks with large amounts of interstitial water have many potential applications as structural materials in biomedical engineering. Quantifying the relationship between micro/nanostructures and their mechanical responses can provide some guidelines for the high-performance mechanical design of counterparts. To this end, we develop a modified physically based constitutive model for examining the effects of the micro/nanostructures of a nanofibrous network on the strain stiffening behaviors of nanocellulose hydrogels under stretching. In addition to the configurational entropy of cellulose nanofiber and mixing energy of water molecule, this theoretical model is particularly concerned with the contribution of the potential energy of hydrogen bond in a thermodynamics framework. Increasing the physical crosslinks between cellulose nanofibers or decreasing the content of water molecules in a certain range can enhance the strain stiffening behaviors of nanocellulose hydrogels. Relatively long and thin cellulose nanofibers have increased tensile strengths. The theoretical predictions are in good agreement with the relevant experimental results. We propose a fiber orientation model for quantifying the relationship between the nanofiber orientation degree and mechanical stretching. This model provides a theoretical foundation for fabricating anisotropic nanofibrous hydrogels via cold drawing.

A pH and Temperature Dual-Responsive Microgel-Embedded, Adhesive, and Tough Hydrogel for Drug Delivery and Wound Healing

Stimuli-responsive hydrogels have attracted much attention over the past decade for potential bioengineering applications such as wound dressing and drug delivery. In this work, a pH and temperature dual-responsive microgel-embedded hydrogel has been fabricated by incorporating poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAAm-co-AAc) based microgel particles into polyacrylamide (PAAm)/chitosan (CS) semi-interpenetrating polymer network (semi-IPN), denoted as microgel@PAM/CS. The resultant hydrogel possesses excellent mechanical properties including stretchability, compressibility, and elasticity. In addition, the microgel@PAM/CS hydrogels can tightly adhere to the surfaces of a variety of tissues such as porcine skin, kidney, intestine, liver, and heart. Moreover, it shows controlled dual-drug release profile of both bovine serum albumin (BSA) (as a model protein) and sulfamethoxazole (SMZ), an antibiotic. Excellent antimicrobial properties are obtained for SMZ-loaded microgel@PAM/CS hydrogels. Compared with traditional drug administration methods such as by mouth, injection, and inhalation, the microgel@PAM/CS hydrogels possess advantages such as higher drug loading efficiency (by more than 80%) and controllable and sustained (over 48 h) release. The microgel@PAM/CS hydrogels can significantly enhance the wound healing process. This work provides a facile approach for the fabrication of multifunctional stimuli-responsive microparticle-embedded hydrogels with semi-IPN structures, and the as-prepared microgel@PAM/CS hydrogels have great potential for applications as smart wound dressing materials in biomedical engineering.

Cortical Bone Model with a Microcrack under Tensile Loading

The fracture mechanics of cortical bone has received much attention in biomedical engineering. It is a fundamental question how the material constants and the geometric parameters of the cortical bone affect the fracture behavior of the cortical bone. In this work, the plane problem for cortical bone with a microcrack located in the interstitial tissue under tensile loading was considered. Using the solution for the continuously distributed edge dislocations as Green's functions, the problem was formulated as singular integral equations with Cauchy kernels. The numerical results suggest that a soft osteon promotes microcrack propagation, while a stiff osteon repels it, but the interaction effect between the microcrack and the osteon is limited near the osteon. This study not only sheds light on the fracture mechanics behavior of cortical bone but also offers inspiration for the design of bioinspired materials in biomedical engineering.

Formation of composite hydrogel of carboxymethyl konjac glucomannan/gelatin for sustained release of EGCG

Development of functional bioinspired hydrogels that have good releases control character is necessary for the application of these materials in biomedical engineering. Herein, we report a composite hydrogel prepared from several biocompatible carboxymethyl konjac glucomannan (CKGM)/gelatin (G)/tannic acid (TA) functional nano-hydroxyapatite (TA@n-HA), which has good biodegradability and pH sensitivity. The mechanism of interaction between hydrogels was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Scanning electron microscopy and Thermogravimetric analysis. The physico-chemical properties of CKGM/G hydrogels have been significantly improved through the incorporation of TA@n-HA within the matrix. Studies in the sustained release of epigallocatechin gallate (EGCG) demonstrated that the TA@n-HA/CKGM/G hydrogels exhibit not only better pH sensitive properties, but also enhanced biocompatibility and encapsulation in comparison to the matrix devoid of TA@n-HA. Consequently, TA@n-HA/CKGM/G hydrogels using EGCG as a drug release model show the potential for drug delivery.

Keratin - based materials in Biomedical engineering

A biomaterial is used to replace tissue or its function within the living body. Many natural occurring polymers like collagen, fibrin, elastin, gelatin, silk fibroin, hyaluronic acid and chitosan, that have been broadly utilized as in biomaterial applications. In addition to this, proteins are known to be used as one of the popular biomaterials because of their capability to work as synthetic ECM. Among this, keratin is a protein used as effective biopolymers in the fabrication of many new biomaterial(s). Various new techniques have been made for their extraction and structural characterization. Keratin is being characterized as repetitive sequences of amino acid that led in the production of self-assembly. The self-assemble character of keratin has attained to develop into many physical appearances such as sponges, nano-particles and films, found helpful in many drug deliveries and biomedical tissue engineering. This manuscript detailed the advanced utilisation of keratin biomaterials in the area of tissue engineering; wound healing, drug delivery, and so on.

Thermoresponsive Nanogels Based on Different Polymeric Moieties for Biomedical Applications.

Nanogels, or nanostructured hydrogels, are one of the most interesting materials in biomedical engineering. Nanogels are widely used in medical applications, such as in cancer therapy, targeted delivery of proteins, genes and DNAs, and scaffolds in tissue regeneration. One salient feature of nanogels is their tunable responsiveness to external stimuli. In this review, thermosensitive nanogels are discussed, with a focus on moieties in their chemical structure which are responsible for thermosensitivity. These thermosensitive moieties can be classified into four groups, namely, polymers bearing amide groups, ether groups, vinyl ether groups and hydrophilic polymers bearing hydrophobic groups. These novel thermoresponsive nanogels provide effective drug delivery systems and tissue regeneration constructs for treating patients in many clinical applications, such as targeted, sustained and controlled release.

Dynamic mechanical analysis of polyethylene terephthalate/hydroxyapatite biocomposites for tissue engineering applications

Synthetic biomaterials are widely used for the treatment of diseased or damaged tissue in the field of tissue engineering. Polyethylene terephthalate (PET) is a synthetic thermoplastic engineering polymer with high commercial and industrial interest and has been widely used as implant material in biomedical engineering. Despite that, PET has limited applications due to its high hydrophobicity. Hydroxyapatite (HA) is one of the known biocompatible ceramic for the development of porous scaffolds for bone replacement and tissue engineering due to its resemblance to the mineral constituents of human bones and teeth. Therefore, HA was functionalized into the PET matrix in order to improve the limitation. In this research, PET-HA nano-biocomposite scaffold was electrospun using the electrospinning system. PET and HA were dissolved using trifluoroacetic acid (TFA) and dichloromethane (DCM). The nanofibrous scaffolds were produced at optimum process parameters. The morphology studies were performed using a Scanning Electron Microscope (SEM) and thermomechanical properties were evaluated using Dynamic Mechanical Analysis (DMA). From the morphology analysis, PET-HA nano-biocomposite scaffold which composed of 96% of PET and 4% of HA, has obtained the largest fiber diameter. The DMA analysis showed that the addition of HA improved mechanical properties. However, PET-HA nano-biocomposite scaffold composed of 98% of PET and 2% of HA was preferred as it has the lower value of storage and loss modulus because the application was focusing on the skin where the more flexible scaffold was needed. The PET-HA nano-biocomposite scaffold fabricated has good potential to be used in tissue engineering applications.

Facile Surface Modification Method for Synergistically Enhancing the Biocompatibility and Bioactivity of Poly(ether ether ketone) That Induced Osteodifferentiation.

Poly(ether ether ketone) (PEEK) is a promising material in biomedical engineering due to its suitable mechanical properties and excellent chemical resistance and biocompatibility. However, the biological inertness of PEEK limits its applications. In this study, we developed a facile approach of immersion to generate a biocompatible and bioactive PEEK that induced osteodifferentiation. First, micropores on the surface of PEEK were introduced by concentrated sulfuric acid and subsequent water immersion, followed by the hydrothermal treatment to reduce residual sulfuric acid. Subsequently, the sulfonated PEEK surface was activated by the oxygen plasma treatment and then coated with a poly(dopamine) (PDA) layer by immersion into the dopamine solution. Finally, the tripeptide Arg-Gly-Asp (RGD) was integrated onto the PDA-coated surface of PEEK by immersion into the RGD peptide solution. The surface characteristics (physical chemistry and biological properties) and the ability to form bonelike apatite were systematically investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, water contact angle analysis, the Archimedes' fluid saturation method, ellipsometry, a quartz crystal microbalance with dissipation monitoring, cell proliferation, real-time reverse transcription polymerase chain reaction analysis, alizarin red staining, immunocytochemistry staining, and simulated body fluid immersion. Collectively, the modified PEEK showed a significantly improved ability to promote cell proliferation, osteogenic differentiation, and bonelike apatite formation in vitro as compared to the PEEK control. These results demonstrate that combined facile surface modifications for PEEK enhance its bioactivity and biocompatibility, and induce osteodifferentiation. This study presents a strategy for broadening the use of PEEK in the application of orthopedic implants and could be industrially scalable in future.

The effect of pre-polymer/cross-linker storage on the elasticity and reliability of PDMS microfluidic devices

Polydimethylsiloxane (PDMS) is a commonly used material in biomedical engineering (Sollier et al. in Lab Chip 11(22):3752–3765, 2011; Palchesko et al. in PLoS ONE 7(12):e51499, 2012; Berthier et al. in Lab Chip 12(7):1224–1237, 2012). Its elastic nature makes PDMS especially attractive for microfluidic large-scale integration (mLSI) technology where micromechanical valves are actuated by deflecting a PDMS membrane under pressure. Therefore, understanding and control of PDMS elastic properties have commercial and scientific significance. In this study, we have investigated the effects of pre-polymer/cross-linker storage conditions on the mechanical properties of cured PDMS films as well as on microfluidic devices. We have showed that when the uncured components of PDMS are exposed to different humidity conditions, the elasticity of the PDMS changes and this is revealed as a change in the Young’s modulus of the cured PDMS. The high humidity (~85%) exposure for 24 h causes PDMS to become softer as confirmed by a significant decrease in the Young’s modulus values from 1.2 to 0.9 MPa. Furthermore, as the PDMS is exposed to high humidity conditions for longer periods (72 h), the Young’s modulus decreases down to 0.7 MPa. We found that exposing only the pre-polymer PDMS (Part A) to humid air does not alter the cured PDMS properties significantly, whereas exposure of the cross-linker (Part B) is responsible for the elasticity change. We have strictly controlled the storage humidity to build more reliable microfluidic chips using mLSI. As a result, actuation pressure of valves (10 psi) and defects of devices (in <30% of chips) are significantly reduced. These results suggest that to improve the manufacturing yield and reliability of PDMS devices, storage humidity should be controlled immediately after the material synthesis.

Nanoscopic dynamics in hybrid hydroxyapatite-CTAB composite

Synthetic hydroxyapatite (HAp) is an important material in biomedical engineering due to its excellent biocompatibility and bioactivity. HAp nanoparticles were synthesized by the co-precipitation method using cetyltrimethylammonium bromide (CTAB) micelles as a template and are characterized using x-ray diffraction, electron microscopy, and thermal gravimetric measurements. Transmission electron microscope (TEM) demonstrates the formation of rod-shaped HAp. Dynamics of CTAB in HAp-CTAB composite as studied by using quasielastic neutron scattering (QENS) technique is reported here. HAp-CTAB composite provides an ideal system for studying the dynamics of CTAB micelles without any aqueous media. QENS data indicate that the observed dynamics are reminiscent of localized motions in ionic micellar systems, consisting of segmental and fast torsional motions. Segmental dynamics has been described with a model, in which hydrogen atoms in the alkyl chain undergoes localized translation diffusion and the CH3 unit associated with the head group undergo 3-fold jump rotation. Within this model, the hydrogen atoms in the alkyl chain undergo diffusion within spherical domains having different radii and diffusivities. A simple linear distribution of the radius and diffusivity has been assumed, in which the CH2 unit nearest to the head group has the least value and the ones furthest from the head group, that is, at the end of the alkyl chain has the largest value. The fast torsional motion is described by a 2-fold jump rotation model. Quantitative estimate of the different parameters characterizing various dynamical motions active within the time scale of the instrument is also presented. We have provided a detailed description of the observed dynamical features in hybrid HAp-CTAB composite, a potential candidate for biomedical applications.

Structural, Mechanical and Tribological Properties of Spark Plasma Sintered Ti6Al4V Alloy

Abstract The influence of spark plasma sintering parameters on the structural, mechanical and tribological characteristics of the Ti6Al4V alloy, which is used as implant material in biomedical engineering, was investigated. The experimental data confirm that full density and attractive mechanical properties can be obtained using the spark plasma sintering method. Tribological tests, performed in dry conditions, allowed the authors to indicate the most suitable sintering parameters. The material characterized by the highest wear resistance was selected for further tribological testing in articulation with UHMWPE in simulated body fluids. Although the weight of the polymeric material articulating against the sintered Ti6Al4V was slightly higher compared to the UHMWPE articulating against the reference material (Ti6Al4V rod), the friction coefficient was lower.

Protein-mediated hydroxyapatite composite layer formation on nanotubular titania

Realising controllable interactions at the bio-nanomaterial interfaces are vital in developing next-generation engineered implant materials. Titanium-based implants are key materials in biomedical engineering due to excellent bulk mechanical properties and biocompatibilities. Advanced bio-interfaces resolving nanostructured modulated surfaces that allow manipulation with the biological molecules is one of the keys to enhance favourable interactions with the surrounding biological species. Here, we developed a protein-mediated hydroxyapatite composite layer on nanotubular titania surface. Green fluorescence protein, engineered to contain hydroxyapatite binding peptides (GFPuv-HABP), was co-deposited with the hydroxyapatite precursors onto the titania nanotubes that are formed by anodisation. Ordered titanium dioxide nanotubular surfaces were coated with hydroxyapatite at physiological pH and temperature using simulated body fluid and pulsed electrochemical cathodisation. The hydroxyapatite deposit interdigitated into the nanotubes, producing a metal oxide-mineral composite. The engineered GFPuv-HABP protein was then self-assembled on the hydroxyapatite, forming a bio-modulated interface. Additionally, the engineered proteins were co-deposited with the precursor ions of hydroxyapatite mineral on the nanotubular titania plate. Bio-mediated assembly resulted in formation of a hybrid composite as an integrated interface on the nanotubular surface. Biomolecular assisted fabrication of hybrid composite interface on metal oxide substrate offers wide range of opportunities to design novel interfaces.

Electrochemically designed interfaces: Hydroxyapatite coated macro-mesoporous titania surfaces

Titanium-based implants are key weight-bearing materials in biomedical engineering due to their excellent bulk mechanical properties and biocompatibility. Designing tissue-material interfaces of titanium implants is essential for an increase in osteointegration of engineered implant materials. Surface morphology is a crucial determinant in the construction of biocompatible and osteointegrative orthopedic and dental implants. Biomimicry of the structural features of bone, specifically its macro-to-mesoporosity, may enable the bone cells to osteointegrate, attain and maintain a physiological strain level. In this study, the surface chemistry and morphology of commercially pure titanium plates were modified using electrochemistry. Titanium oxide substrates were prepared by dual acid polishing and alkaline anodization using 0.1M KOH in an electrochemical cell with a stainless steel cathode and an anodic voltage of 40V at 20°C for 3min. FE-SEM characterization revealed macro-mesoporous anodized titania surfaces, which were coated by hydroxyapatite using simulated body fluid and pulsed electrochemical deposition at 80°C, while unprocessed commercially pure titanium surfaces were used as controls. The calcium phosphate deposit on titania plates was characterized as calcium-deficient carbonated hydroxyapatite using XRD, FTIR and FE-SEM, whereas the deposit on non-porous, non-functionalized titanium surfaces was characterized as carbonated apatite. The adhesion strength of the hydroxyapatite coated titania surfaces was 38±10MPa, implying that these surfaces may be suitable for biological and chemical functionalization of medical implants to tune bioactivity, including delivering drugs.

Compressive Strength of Rice Husk Filled Resin

The findings for strengthening and repair of implant materials are stepping up to ensure better protection of the patients. The utilization of composite resin is favourable to combat this challenge. However, it being a brittle material does not entitle it to be used in the design. Hence, epoxy resin combining with silicon oxide filler from the rice husk; is a relatively new material in biomedical engineering, enable it to meet its fullest strength and flexibility. Work was performed at laboratory to extract the silicone compound from rice husk and as well investigate the compressive strength of rice husk filled resin material. Initially the rice husk was experimented by undergoing pre-treatment, chemical treatment and incineration process to obtain silicone compound. The silicone compound was later mixed with epoxy resin at different percentage of filler. In the final stage, the compressive strength of rice husk filled resin was analyzed and affirmed experimentally based on the ASTM standards. The results obtained were then analyzed using analytical software SPSS. Epoxy resin filled with 20% silica from rice husk gave the optimum compressive strength of 90 Mpa.

Preparation of silver nanoparticles with antimicrobial activities and the researches of their biocompatibilities

Silver nanoparticles were prepared by chemical reduction method using chitosan as stabilizer and ascorbic acid as reducing agent in this work. The silver/chitosan nanocomposites were characterized in terms of their particle sizes and morphology by using UV spectrophotometer, nano-grainsize analyzer, and transmission electron microscopy. Antibacterial activities of these nanocomposites were carried out for Staphylococcus aureus and Escherichia coli. The silver nanoparticles exhibited significantly inhibition capacity towards these bacteria. Detailed studies on the biocompatibility of the silver/chitosan nanocomposites were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell adhesion test. The results indicated that these silver/chitosan nanocomposites were benefit for the proliferation and adhesion of L-929 cells, and the biocompatibilities between the nanocomposites and the cells would become better with the culturing days. We anticipated that these silver/chitosan nanocomposites could be a promising candidate as coating material in biomedical engineering and food packing fields wherein antibacterial properties and biocompatibilities are crucial.

Surface Characterization and in Vitro Blood Compatibility of Poly (Ethylene Terephthalate) Immobilized with Hirudin

Poly (ethylene terephthalate)(dacron, PET) films were exposed under argon plasma glow discharge with different glows and induced polymerization of acrylic acid(AA) in order to introduce carboxylic acid group onto PET (PET-AA) assisted by ultraviolet radiation(UV). Hirudin-immobilized PET (PET-HRD) films were prepared by the grafting of PET-AA, followed by chemical reaction with hirudin. The surface structure of the treated PET was determined by X-ray photoelectron spectroscopy (XPS). The wettability, surface free energy, and interface free energy of the films were investigated by contact angle measurement. The blood compatibility of the films was assessed by platelet-adhesion test and fibrinogen conformational change measurements to evaluate the viability of the materials in biomedical engineering. Measurement by scanning electron microscopy (SEM) revealed that the amounts of adhered, aggregated and morphologically changed platelets were reduced on the hirudin-immobilized PET films. Enzyme-linked-immunoassay measurements that disclosed fibrinogen conformational changes showed results consistent with the platelets' behavior.

Si–N–O Films Synthesized by Plasma Immersion Ion Implantation and Deposition (PIII&amp;D) for Blood-Contacting Biomedical Applications

Silicon-Oxynitride (Si-N-O) films were fabricated on silicon wafers by silicon cathodic arc combined with plasma immersion ion implantation and deposition. The blood compatibility of the films was assessed by platelet-adhesion test and fibrinogen conformational change measurements to evaluate the viability of the materials in biomedical engineering. Significantly, a better platelet-adhesion behavior, as manifested by a smaller number and weaker aggregation as well as pseudopodium, was observed on the Si-N-O samples compared to the low-temperature isotropic pyrolytic carbon, which is the most common material used in blood-contacting biomedical devices such as artificial heart valves. Enzyme-linked-immunoassay measurements that disclose fibrinogen conformational changes show results that are consistent with the platelets' behavior, which is believed to be involved in the activation process. The good blood compatibility of the films can be attributed to the high hydrophilicity and surface free energy arising from the Si-N, Si-N-O, and Si-O bonding states. The interfacial reactions between fibrinogen, platelets, and material surface are discussed from the perspective of thermodynamics. The promising blood compatibility of the Si-N-O films is of both scientific and commercial interests in biomedical engineering

Materials in biomedical engineering. S. N. Levine, (consulting editor and conference chairman) of the Annals of the New York Academy of Sciences, Vol. 146, Art. 1 pp. 1‐359

Materials in biomedical engineering. S. N. Levine, (consulting editor and conference chairman) of the Annals of the New York Academy of Sciences, Vol. 146, Art. 1 pp. 1‐359

MATERIALS IN BIOMEDICAL ENGINEERING

The SciencesVolume 6, Issue 3 p. 10-14 MATERIALS IN BIOMEDICAL ENGINEERING First published: August 1966 https://doi.org/10.1002/j.2326-1951.1966.tb02451.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume6, Issue3August 1966Pages 10-14 RelatedInformation