Potential Applications In Biomedical Engineering Research Articles

Cellular uptake of active nonspherical nanoparticles

Due to the potential applications in biomedical engineering, it becomes more and more important to understand the process of engulfment and internalization of nanoparticles (NPs) by cell membranes. Despite the fact that the interaction between cell membranes and passive particles has been widely studied, the interaction between cell membranes and self-propelled nonspherical NPs remains to be elucidated. Here, we present a theoretical model to systematically investigate the influence of the active force, aspect ratio of NPs, particle size, and membrane properties (adhesion energy density and membrane tension) on the cellular uptake of a nonspherical nanoparticle. It is found that the active force generated by an NP can trigger a type of first-order wrapping transition from a small partial wrapping state to a large one. In addition, the phase diagram in the force-aspect ratio (particle size, adhesion energy density, and membrane tension) space displays more complex behaviors compared with that for the passive wrapping mediated merely by adhesion. These results may provide useful guidance to the study of activity-driven cellular entry of active particles into cells.

Electro-fluid-dynamics (EFD) of soft-bodied organisms swimming through mucus having dilatant, viscous, and pseudo-plastic properties

The sperm propelling mechanism has been proposed as a possible resource for soft micro-robots in confined spaces, with potential applications in biomedical engineering. Human sperm cells essentially swim through the non-Newtonian liquid (cervical mucus) to reach their target. Thus, sperm cells swimming through non-Newtonian fluids is not vital only for physiology, but also for the fabrication of swimming micro-robots. Inspired by these remarkable applications, we examine the basic mechanics of spermatozoa motility using an undulating sheet model. This undulating sheet is bounded between two rigid walls which is self-propeling in the negative axial direction. The liquid around the spermatozoa is taken as Carreau fluid with electro-osmotic properties. The application of the lubrication approximation results in the reduction of momentum equations. The resulting ODE is solved numerically via the finite difference method and MATLAB’s built-in routine bvp5c. The unknowns that are present in the boundary conditions are refined by the root-finding algorithm. Power losses, cell speed, flow rate, velocity of the fluid, and streamline pattern are visualized by graphs. The findings of this study have important implications for the designing and optimization of electrically controlled microswimmers.

4D Multimaterial Printing of Soft Actuators with Spatial and Temporal Control.

Soft actuators (SAs) are devices which can interact with delicate objects in a manner not achievable with traditional robotics. While it is possible to design a SA whose actuation is triggered via an external stimulus, the use of a single stimulus creates challenges in the spatial and temporal control of the actuation. Herein, a 4D printed multimaterial soft actuator design (MMSA) whose actuation is only initiated by a combination of triggers (i.e., pH and temperature) is presented. Using 3D printing, a multilayered soft actuator with a hydrophilic pH-sensitive layer, and a hydrophobic magnetic and temperature-responsive shape-memory polymer layer, is designed. The hydrogel responds to environmental pH conditions by swelling or shrinking, while the shape-memory polymer can resist the shape deformation of the hydrogel until triggered by temperature or light. The combination of these stimuli-responsive layers allows for a high level of spatiotemporal control of the actuation. The utility of the 4D MMSA is demonstrated via a series of cargo capture and release experiments, validating its ability to demonstrate active spatiotemporal control. The MMSA concept provides a promising research direction to develop multifunctional soft devices with potential applications in biomedical engineering and environmental engineering.

Mechanical responsive visible structural colors based on chiral-nematic cellulose nanocrystals photonic hydrogels

It has been extensively reported that cellulose nanocrystals (CNCs) are capable of exhibiting structural colors due to their unique chiral nematic self-assembly. However, further investigation is required to effectively utilize these remarkable properties for addressing real-world challenges, such as development of advanced materials like mechanical sensors and smart wearable devices. One particular challenge has been maintaining the refractive properties of structural colors resulting from the CNCs structure within the visible spectrum. In this study, we introduce a one-step hydrogel fabrication method involving chiral nematic CNC films embedded within poly(acrylic acid). These hydrogels exhibit naked-eye-visible structural colors and exhibit responsiveness to mechanical stresses. The resulting photonic hydrogels exhibit a blue shift in response to mechanical stretching. The hydrogels demonstrated self-recovery capabilities, as observed through cyclic loading–unloading stress tests. The color of the materials was characterized using UV–Vis spectroscopy to determine the wavelength of the reflected light. Additionally, we investigated the mechanism of CNCs orientation change using 2D-X-ray diffraction. Demonstrated by our simulation study, the morphology of the CNC bundles significantly influenced the characteristics of the chiral nematic structure as they orient due to the force application. Notably, the color change of the photonic hydrogels was reversible within the optimal range of applied force and can be repeated numerous times. This work presents a new strategy for fabricating optically functional photonic hydrogels with stimuli-responsive properties, enabling their potential applications in biomedical engineering and wearable responsive sensor technologies.

3D Printing of Interpenetrating Network Flexible Hydrogels with Enhancement of Adhesiveness.

3D printing of hydrogels has been widely explored for the rapid fabrication of complex soft structures and devices. However, using 3D printing to customize hydrogels with both adequate adhesiveness and toughness remains a fundamental challenge. Here, we demonstrate mussel-inspired (polydopamine) PDA hydrogel through the incorporation of a classical double network (2-acrylamido-2-methylpropanesulfonic acid) PAMPS/(polyacrylamide) PAAm to achieve simultaneously tailored adhesiveness, toughness, and biocompatibility and validate the 3D printability of such a hydrogel into customized architectures. The strategy of combining PDA with PAMPS/PAAm hydrogels leads to favorable adhesion on either hydrophilic or hydrophobic surfaces. The hydrogel also shows excellent flexibility, which is attributed to the reversible cross-linking of PDA and PAMPS, together with the long-chain PAAm cross-linking network. Among them, the reversible cross-linking of PDA and PAMPS is capable of dissipating mechanical energy under deformation. Meanwhile, the long-chain PAAm network contributes to maintaining a high deformation capability. We establish a theoretical framework to quantify the contribution of the interpenetrating networks to the overall toughness of the hydrogel, which also provides guidance for the rational design of materials with the desired properties. Our work manifests a new paradigm of printing adhesive, tough, and biocompatible interpenetrating network hydrogels to meet the requirements of broad potential applications in biomedical engineering, soft robotics, and intelligent and superabsorbent devices.

Biomedical aspects of entropy generation on MHD flow of TiO2-Ag/blood hybrid nanofluid in a porous cylinder

This study aims to analyze the heat transfer behavior of the magnetohydrodynamic blood-based Casson hybrid nanofluid in the occurrence of a non-Fourier heat flux model and linear thermal radiation over a horizontal porous stretching cylinder with potential applications in biomedical engineering. The present investigation utilised titanium dioxide and silver nanoparticles, which exhibit considerable potential in the realm of cancer therapy. Thus, there is a growing interest among biomedical engineers and clinicians in the study of entropy production as a means of quantifying energy dissipation in biological systems. Suitable self-similarity variables are employed to transform the nonlinear mathematical equations such as velocity, temperature, skin friction coefficient, and heat transfer rate, which are computed via homotopy perturbation method (HPM). HPM computations have been executed to solve the influences of various parameters such as porosity parameter Curvature parameter Casson parameter inertia coefficient thermal relaxation parameter radiation Eckert number Brinkman number and temperature difference parameter The comparison using the homotopy perturbation technique produces a more accurate and reliable consequence than the numerical method (Runge-Kutta method). The higher values of the Casson and Curvature parameters decrease the velocity profile. The temperature profile of M = 1 and M = 0 increases with improving values of the thermal relaxation parameter. Entropy generation rises to enhance Brinkman number values, whereas Bejan number exhibits the reverse influence. Improving the value of the heat source parameter declines the Nusselt number.

A Fast Soft Continuum Catheter Robot Manufacturing Strategy Based on Heterogeneous Modular Magnetic Units.

Developing small-scale continuum catheter robots with inherent soft bodies and high adaptability to different environments holds great promise for biomedical engineering applications. However, current reports indicate that these robots meet challenges when it comes to quick and flexible fabrication with simpler processing components. Herein, we report a millimeter-scale magnetic-polymer-based modular continuum catheter robot (MMCCR) that is capable of performing multifarious bending through a fast and general modular fabrication strategy. By preprogramming the magnetization directions of two types of simple magnetic units, the assembled MMCCR with three discrete magnetic sections could be transformed from a single curvature pose with a large tender angle to a multicurvature S shape in the applied magnetic field. Through static and dynamic deformation analyses for MMCCRs, high adaptability to varied confined spaces can be predicted. By employing a bronchial tree phantom, the proposed MMCCRs demonstrated their capability to adaptively access different channels, even those with challenging geometries that require large bending angles and unique S-shaped contours. The proposed MMCCRs and the fabrication strategy shine new light on the design and development of magnetic continuum robots with versatile deformation styles, which would further enrich broad potential applications in biomedical engineering.

A spatiotemporal controllable crosslinking route for preparing tough tissue-like anisotropic PVA hydrogel

Highly ordered and multi-layered assembly structures endow biological tissues with excellent and unique mechanical properties. Up to now, it is difficult to prepare artificial materials with the tissue-like structures through the traditional gelation routes for the lack of a spatiotemporal controllable cross-linking strategy. Here we propose a dynamic borate ester bonds assisted method to realize the spatiotemporal controllable cross-linking of PVA hydrogel, which make it feasible to prepare biomimetic anisotropic PVA hydrogel architectures.In this work, the directional alignment and re-crosslinking of the polymer chains can be performed as needed. The fracture strength of the obtained anisotropic hydrogel can reach ∼8.0 MPa, which is about 34 and 12 times that of the hydrogels obtained by freezing-thawing and salting-out respectively. Highly ordered structure and good anti-swelling of the hydrogels obtained by this method are determined by Polarizing microscope, X-ray diffraction and Scanning electron microscope. Various tissue-like hydrogels with hierarchical uniaxial or multi-layered assembly are prepared with this method. This study provides a facile, friendly and spatiotemporal controllable route to prepare tough biomimetic hydrogel architectures, which have potential application in biomedical engineering or soft machines.

An extremely tough and ionic conductive natural-polymer-based double network hydrogel.

Hydrogels are widely used in fields such as drug delivery, tissue regeneration, soft robotics and flexible smart electronic devices, yet their application is often limited by unsatisfactory mechanical behaviors. Among the various improvement strategies, double network (DN) hydrogels from synthetic polymers demonstrated impressive mechanical properties, while those from natural polymers were usually inferior. Here, a novel DN hydrogel composed fully of natural polymers exhibiting remarkable mechanical properties and conductivity is prepared by simply soaking a virgin gellan gum/gelatin composite hydrogel in a mixed solution of Na2SO4 and (NH4)2SO4. This hydrogel exhibits a tunable Young's modulus (0.08 to 42.6 MPa), good fracture stress (0.05 to 7.5 MPa), good fracture stretch (1.4 to 7.1), high fracture toughness (up to 27.7 kJ m-2), and high ionic conductivity (up to 11.4 S m-1 at f = 1 kHz). The improvement in the mechanical properties of the DN gel is attributed to the chain-entanglement crosslinking points introduced by SO42- in the gelatin network and the electrostatic interaction crosslinking points introduced by Na+ in the gellan gum network. The high ionic conductivity of the DN gel is attributed to the infiltration of the DN gel in a salt solution of high concentration. The developed gellan gum/gelatin DN hydrogel has shown a new pathway towards strengthening natural-polymer-based DN hydrogels and towards potential applications in biomedical engineering and flexible electronic devices.

Biodegradable wet-spun fibers modified with antimicrobial agents for potential applications in biomedical engineering

Wet-spinning is a non-solvent induced phase inversion technique that allows the production of continuous polymeric microfibers, with a uniform morphology, based on the principle of precipitation. It allows the production of 3D fibrous constructs with an intricated architecture that facilitates cell infiltration, something that is very limited in electrospun nanofibrous mats, thus increasing its interest in biomedicine. Wet-spun scaffolds are also more easily processed and can be loaded with a variety of biomolecules of interest. Antimicrobial agents that display a broad spectrum of activity against bacteria, fungi and viruses have been combined with such constructs demonstrating great potential to fight infections. In the present work, we explore the use of wet-spinning to process both natural and synthetic biodegradable polymers in the form of microfibers, and the necessary processes to modify their surface to increase their antimicrobial profile. The synergistic potential of specialized biomolecules within wet-spun fibrous architectures are also highlighted.

Synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinking on the properties of agar

In this work, the modification of agar is presented with the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinked agar. The effect of crosslinking agar with succinic acid on tensile strength and water absorption were studied. Crosslinking was confirmed with Fourier infrared spectroscopy. The tensile strength of agar was increased by 70% by succinic acid crosslinking (from55 ± 9.97 MPa to 93.40 ± 9.97 MPa) and the crosslinked agar absorbed only 18.66% water compared to uncrosslinked agar. The tensile strength of agar was increased by 56% by bacterial cellulose reinforcement (55 ± 9.97 MPa to 86.30 ± 14.70 MPa). The strength of agar was improved by 101% by the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinking (55 ± 9.97 MPa to 111 ± 12.30 MPa). Cytocompatibility studies of the developed films suggested that the crosslinked samples can also have potential applications in biomedical engineering apart from packaging applications.

Bactericidal efficacy of nanopatterned surface tuned by topography

Due to the exciting physical mechano-bactericidal approach developed in recent years using nanopatterned surfaces with its potential applications in biomedical engineering, now it becomes crucially important to fabricate optimal surface structures so as to achieve the best bactericidal ability. In this paper, the bactericidal efficacy of the cylindrical nanopillar-patterned surface and the sinusoidal nanopillar-patterned surface is presented via minimizing total free energy for a bacterial cell adhered on these two kinds of surfaces. Our theoretical analyses show that the adhesion depth at equilibrium along the nanopillar shafts and the corresponding stretching degree is related to the the nanopillar density and nanopillar radius. The bactericidal efficacy on the nanopillar-patterned surface is determined by the combination of nanopillar density and naopillar radius, which is also supported by the phase diagrams obtained, showing that at large internanopillar spacing and nanopillar radius, the sinusoidal nanopillar-patterned surface is more advantageous in bactericidal efficacy, while in small interspacing and nanopillar radius, the cylindrical nanopillar-patterned surface structure is more powerful. The conclusions obtained in this paper unveil how the mechano-bactericidal effect is achieved by tuning the topography of the nanopatterned surface, a technique helpful to the optimal design and fabrication of bio-mimicking nanotextured surfaces.

Nanoceria: Metabolic interactions and delivery through PLGA-encapsulation.

Cerium oxide nanoparticles (nanoceria) have recyclable antioxidative activity. It has numerous potential applications in biomedical engineering, such as mitigating damage from burns, radiation, and bacterial infection. This mitigating activity is analogous to that property of metabolic enzymes such as superoxide dismutase (SOD) and catalase - scavengers of reactive oxygen species (ROS). Therefore, nanoceria can protect cells from environmental oxidative stress. This therapeutic effect prompted studies of nanoceria and metabolic enzymes as a combination therapy. The activity and structure of SOD, catalase, and lysozyme were examined in the presence of nanoceria. A complementary relationship between SOD and nanoceria motivated the present work, in which we explored a method for simultaneous delivery of SOD and nanoceria. The biocompatibility and tunable degradation of poly(lactic-co-glycolic acid) (PLGA) made it a candidate material for encapsulating both nanoceria and SOD. Cellular uptake studies were conducted along with a cytotoxicity assay. The antioxidative properties of PLGA-nanoceria-SOD particles were verified by adding H2O2 to cell culture and imaging with fluorescent markers of oxidative stress. Our results suggest that PLGA is a suitable encapsulating carrier for simultaneous delivering nanoceria and SOD together, and that this combination effectively reduces oxidative stress in vitro.

OVERVIEW OF INEXPENSIVE PRODUCTION ROUTES OF BACTERIAL CELLULOSE AND ITS APPLICATIONS IN BIOMEDICAL ENGINEERING

Bacterial cellulose (BC) is an innovative polymeric nanofibre, which meets the demands of rapidly advancing industries, such as biomedical engineering, food packaging, pulp and paper and electrical appliance engineering. The versatility of bacterial cellulose is largely due to its unique properties, such as high crystallinity, high thermal stability, high water absorption capacity, hydrophilicity, good mechanical strength, biodegradability, high biocompatibility and high porosity, making it well-suited for applications in various fields. In recent years, advances for enhancing the applicability of BC through modification and its inclusion into composites have been in focus. Unfortunately, despite the multiple advantages it offers, the production cost of BC is too high, thus reducing/limiting its commercial attractiveness and industrial scale production. This paper is an overview of the current research trends for developing cheaper BC production pathways and of recent advances performed so far with the prospect of enhancing its potential application in biomedical engineering.

Glycolide/L-Lactide Copolymer (PGLA) Fibers Formed by Wet Spinning from Solution and Modified with Ceramic Nanoadditives

Abstract The paper presents the results of research into glycolide/L-lactide copolymer (PGLA) fiber formation by wet spinning from solution. The selected process conditions led to fibers with a specific tensile strength of more than 35 cN/tex. Furthermore, ceramic nanoadditives such as hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) were used to obtain fibers with osteoconductive properties. It was found that the ceramic nanoadditives reduced the specific strength of fibers (to 24 cN/tex for β-TCP and to 27 cN/tex for HAp). The paper also presents wide-angle X-ray scattering (WAXS) evaluation of the supramolecular structure of the fibers as well as their porosity parameters and microscopic structure. The obtained fibers were woven into a textile fabric with potential applications in biomedical engineering.

Fabrication and Friction Coefficient of Graphene Oxide Reinforced Hydroxyapatite Composite

Graphene oxide (GO) reinforced hydroxyapatite (HA) composites with various contents of GO (HA/GO-C) were synthesized with addition of cetyltrimethyl ammonium bromide (CTAB) by a wetchemical precipitation method using diammonium hydrogen phosphate ((NH4)2HPO4) and calcium nitrate (Ca(NO3)2 · 4H2O) as the initial reactants, and their structure, morphology, crystallization, specific surface area were studied by FT-IR, SEM, Raman spectroscopy, XRD and BET. Particularly, the influence of GO addition and appiled load on the friction coefficient of the obtained composites was investigated. Also, the influence of GO addition on microhardness of the composite was evaluated. The results suggested that HA successfully grafted over GO nanosheets whose structure was preserved. The layer spacing of HA/GO-C composite was enlarged by addition of CTAB in synthesis process. The friction coefficient of the composite gradually decreased with increase of GO content in composite and increased with increase in applied load. The microhardness of the composites increased with increase of GO content. The obtained HA/GO-C composites may have a potential application in biomedical engineering.

HOPG/ZnO/HOPG pressure sensor

Pressure sensor is one of the most commonly used sensors in the research laboratories and industries. These are generally categorized in three different classes of absolute pressure sensors, gauge pressure sensors, and differential pressure sensors. In this paper, we fabricate and assess the pressure sensitivity of the current vs. voltage diagrams in a graphite/ZnO/graphite structure. Zinc oxide layers are deposited on highly oriented pyrolytic graphite (HOPG) substrates by sputtering a zinc target under oxygen plasma. The top electrode is also a slice of HOPG which is placed on the ZnO layer and connected to the outside electronic circuits. By recording the I-V characteristics of the device under different forces applied to the top HOPG electrode, the pressure sensitivity is demonstrated; at the optimum biasing voltage, the device current changes 10 times upon changing the pressure level on the top electrode by 20 times. Repeatability and reproducibility of the observed effect is studied on the same and different samples. All the materials used for the fabrication of this pressure sensor are biocompatible, the fabricated device is anticipated to find potential applications in biomedical engineering.

Functional self-healing materials and their potential applications in biomedical engineering

With the development of smart materials, stimulus-responsive self-repairing materials attract more and more research attention. Although self-healing materials including concretes, rubbers, and hydrogels have been extensively investigated in the past decades, novel functionalities or properties such as shape memory, sol–gel transition, adhesion, anti-biofouling, and electronic/magnetic property have been introduced to self-repairing systems in recent years in order to broaden the scope of their applications in energy, drug delivery, tissue adhesion, cell culture, etc. In this paper, we first present an overview of the general strategies to prepare self-healing materials and the characterization methods to assess their healing performance. Then, we mainly focus on reviewing recent progress in novel self-healing materials possessing unique functionalities and their potential applications in biomedical engineering. Finally, the challenges and scope for future development are also discussed.

CTAB-assisted hydrothermal synthesis of Cu2Se films composed of nanowire networks

A simple hydrothermal method has been developed to synthesize Cu2Se film on copper foil with the assistance of cetyltrimethylammonium bromide (CTAB) as a surfactant. The Cu2Se film was constructed by novel nanowire networks with length up to 50µm. The obtained product was characterized by XRD, SEM, HRTEM, Raman, and XPS techniques, revealing that Cu2Se nanowire possessed single-crystal structures. The shape of Cu2Se film changed from nanowire networks to perfect microflowers as the amount of CTAB increased. Such Cu2Se film may have great potential applications in biomedical engineering, sensors, and catalysis.

Transportation of ionic liquids in a porous micro-channel induced by peristaltic wave with Joule heating and wall-slip conditions

This article presents a mathematical model for studying peristaltic mechanism of combine pressure and electro-osmotically driven flow of ionic liquids through a micro-channel having electrokinetic effects. The velocity slip and the thermal slip conditions at the channel wall are taken into account for investigating the thermomechanical interactions. The micro-channel is assumed to have porous structure. The governing equations for fluid flow and heat transfer in the electrical double layer (EDL) together with the Poisson-Boltzmann equation are considered. The analytical solutions have been obtained under low Reynolds number and long wave length assumptions. It is also assumed that the channel height is much greater than the thickness of the electrical double layer (EDL). The essential features of electro-osmotically driven flow and associated heat transfer characteristics in a micro-channel are clearly demonstrated by varying dimensionless parameters for velocity profile, temperature profile, pressure distribution, stream function, wall shear stress and the Nusselt number. The pressure drop exhibits a linear dependence on the flow rate. The study reveals that the electro-osmotic parameter has an enhancing effect on the size of the trapping bolus while the reducing effect on porous permeability of the channel. The temperature distribution is significantly influenced by Joule heating parameter and Brinkman number. The study bears the potential applications in biomedical engineering for the development of microfluidic devices in particular microfluidic pump to transport small volume of ionic liquids by maintaining temperature distribution.