Bioinspired approaches for medical devices

Functionalized TMC and ε-CL elastomers with shape memory and self-healing properties

Introduction: Smart elastomers, which possess self-healing and shape memory capabilities, have immense potential in the field of biomedical applications. Polycarbonates and polyesters have gained widespread interest due to their remarkable biocompatibility over the last century. Nevertheless, the lack of functional versatility in conventional polyesters and polycarbonates means that they fall short of meeting the ever-evolving demands of the future. Methods: This paper introduced a new smart elastomer, named mPEG43-b-(PMBC-co-PCL)n, developed from polyester and polycarbonate blends, that possessed shape memory and self-heal capabilities via a physical crosslinking system. Results: The material demonstrated a significant tensile strength of 0.38 MPa and a tensile ratio of 1155.6%, highlighting its favorable mechanical properties. In addition, a conspicuous shape retrieval rate of 93% was showcased within 32.5 seconds at 37°C. Remarkably, the affected area could be repaired proficiently with no irritation experienced during 6h at room temperature, which was indicative of an admirable repair percentage of 87.6%. Furthermore, these features could be precisely modified by altering the proportion of MBC and ε-CL to suit individual constraints. Discussion: This innovative elastomer with exceptional shape memory and self-heal capabilities provides a solid basis and promising potential for the development of self-contracting intelligent surgical sutures in the biomedical field.

Fluid manipulation via multifunctional lubricant infused slippery surfaces: principle, design and applications

Water-repellent interfaces with high performance have emerged as an indispensable platform for developing advanced materials and devices. Inspired by the pitcher plant, slippery liquid-infused porous surfaces (SLIPSs) with reliable hydrophobicity have proven to possess great potential for various applications in droplet and bubble manipulation, droplet energy harvesting, condensation, fog collection, anti-icing, and anti-biofouling due to their excellent properties such as persistent surface hydrophobicity, molecular smoothness, and fluidity. This review aims to introduce the development history of interaction between SLIPSs and fluids as well as the design principles, preparation methods, and various applications of some of the more typical SLIPSs. The fluid manipulation strategies of the slippery surfaces have been proposed including the wettability pattern, oriented micro-structure, and geometric gradient. At last, the application prospects of SLIPSs in various fields and the challenges in the design and fabrication of slippery surfaces are analyzed. We envision that this review can provide an overview of the fluid manipulating processes on slippery surfaces for researchers in both academic and industrial fields.

Engineering a Smart Nanofluidic Sensor for High-Performance Peroxynitrite Sensing through a Spirocyclic Ring Open/Close Reaction Strategy

Peroxynitrite (ONOO^-) is an important reactive oxygen/nitrogen species that participates in a range of physiological and pathological processes by modulating ion flux through biological channels. Inspired by a ONOO^--regulated K⁺ channel in vivo, herein, we describe the construction of a smart ONOO^--driven nanosensor using a spirocyclic ring open/close reaction approach. The prepared nanosensor possessed a prominent ONOO^- selectivity and sensitivity and rapid response (∼90 s) owing to the specific reaction between ONOO^- and ligands on the nanosensor surface with a high ion rectification ratio (∼10) and ion gating ratio (∼4). Moreover, this nanosensor system also exhibits excellent stability and recyclability. Thus, these results will provide a new direction for the design of nanochannel-based sensors for future practical and biological applications.

Lubricant-Infused PET Grafts with Built-In Biofunctional Nanoprobes Attenuate Thrombin Generation and Promote Targeted Binding of Cells

New surface coatings that enhance hemocompatibility and biofunctionality of synthetic vascular grafts such as expanded poly(tetrafluoroethylene) (ePTFE) and poly(ethylene terephthalate) (PET) are urgently needed. Lubricant-infused surfaces prevent nontargeted adhesion and enhance the biocompatibility of blood-contacting surfaces. However, limited success has been made in incorporating biofunctionality onto these surfaces and generating biofunctional lubricant-infused coatings that both prevent nonspecific adhesion and enhance targeted binding of biomolecules remains a challenge. Here, a new generation of fluorosilanized lubricant-infused PET surfaces with built-in biofunctional nanoprobes is reported. These surfaces are synthesized by starting with a self-assembled monolayer of fluorosilane that is partially etched using plasma modification technique, thereby creating a hydroxyl-terminated fluorosilanized PET surface. Simultaneously, silanized nanoprobes are produced by amino-silanizing anti-CD34 antibody in solution and directly coupling the anti-CD34-aminosilane nanoprobes onto the hydroxyl terminated, fluorosilanized PET surface. The PET surfaces are then lubricated, creating fluorosilanized biofunctional lubricant-infused PET substrates. Compared with unmodified PET surfaces, the designed biofunctional lubricant-infused PET surfaces significantly attenuate thrombin generation and blood clot formation and promote targeted binding of endothelial cells from human whole blood.

Dynamic Hybrid Colloidosomes via Electrostatic Interactions for pH-Balanced Low Premature Leakage and Ultrafast Cargo Release

A trade-off between minimized premature leakage and rapid cargo release on demand is an intractable obstacle faced by smart delivery systems that restrains them from lab to market. To address this dilemma, dynamic hybrid colloidosomes relying on strong yet reversible electrostatic interactions are developed, simply through one-pot cooperative self-assembly of silica nanoparticles and fluorescent carbon dots at the interface of emulsion droplets. Specifically, pH-driven charge reversal of zwitterionic carbon dots leads to immediate electrostatic conversion between the two building blocks from attraction to repulsion. This makes robust locking and instantaneous breakdown of the colloidosomes subtly balanced, thus enabling low off-state leakage (10.5% over 7 days) while ultrafast on-state release (>90% within 5 min) upon an acidic stimulus. We envision that such biocompatible, traceable, and smart colloidosomes will offer unique opportunities for broad applications as on-demand release is desired.

Highly Porous Microcarriers for Minimally Invasive In Situ Skeletal Muscle Cell Delivery

Microscale cell carriers have recently garnered enormous interest in repairing tissue defects by avoiding substantial open surgeries using implants for tissue regeneration. In this study, the highly open porous microspheres (HOPMs) are fabricated using a microfluidic technique for harboring proliferating skeletal myoblasts and evaluating their feasibility toward cell delivery application in situ. These biocompatible HOPMs with particle sizes of 280-370 µm possess open pores of 10-80 µm and interconnected paths. Such structure of the HOPMs conveniently provide a favorable microenvironment, where the cells are closely arranged in elongated shapes with the deposited extracellular matrix, facilitating cell adhesion and proliferation, as well as augmented myogenic differentiation. Furthermore, in vivo results in mice confirm improved cell retention and vascularization, as well as partial myoblast differentiation. These modular cell-laden microcarriers potentially allow for in situ tissue construction after minimally invasive delivery providing a convenient means for regeneration medicine.

Two dimensional nanomaterial-based separation membranes

Two dimensional nanomaterials including graphene, hexagonal boron-nitride, molybdenum disulfide, etc., provide immense potentials for separation applications. However, the tradeoff between selectivity and permeability in choosing 2D nanomaterial-based membrane is inevitable, limiting the progress on separation efficiency for mass industrial applications. To target these issues, versatile strategies such as the rational design of predefined interlayer channels, membrane nanopores, and reasonable functionalization, as well as new mechanisms have been emerged. In this review, we introduce the recent progress on separation mechanisms of 2D nanomaterial-based membranes with different structures (including the interlayer channels type and the membrane nanopores type) and their inner surface functionalization. Moreover, the interface designs are discussed, in terms of employing dynamic liquid-liquid/liquid-gas interfaces, to advance the selectivity and permeability of the membranes. We further discuss the variety of separation applications based on 2D nanomaterial-based membranes. The authors hope this review will inspire the active interest of many scientists in the area of the development and application of membrane science.

Dual Therapy Coating on Micro/Nanoscale Porous Polyetheretherketone to Eradicate Biofilms and Accelerate Bone Tissue Repair

Defective osteogenesis and latent infections continue to be two major issues in the therapy of bone tissue regeneration. In this study, a unique hierarchically micro/nanoscale-architecture is first proposed and produced on polyetheretherketone (PEEK). Besides, a "simvastatin-PLLA film-tobramycin microspheres" delivery system is subsequently fabricated to endow the PEEK implant with osteogenic and antibacterial capabilities. In vitro antibacterial evaluations confirm that the decorated PEEK scaffolds possess excellent resistance against planktonic/adherent bacteria. In vitro cell attachment/proliferation, lactate dehydrogenase (LDH) content, alkaline phosphatase (ALP) activity, calcium mineral deposition experiments, and real-time PCR analysis all exhibit that the superior proliferation rate and osteo-differentiation potential of MC3T3-E1 pre-osteoblasts are presented on the PEEK samples with dual functional decoration. In the mouse calvarial defect model, the micro-CT and histological results demonstrate that our scaffolds display a remarkable bone forming capability. Generally, the PEEK scaffolds co-endowed with simvastatin and tobramycin microspheres possess great potential in clinics.

Lubricant-Infused Surfaces with Built-In Functional Biomolecules Exhibit Simultaneous Repellency and Tunable Cell Adhesion

Lubricant-infused omniphobic surfaces have exhibited outstanding effectiveness in inhibiting nonspecific adhesion and attenuating superimposed clot formation compared with other coated surfaces. However, such surfaces blindly thwart adhesion, which is troublesome for applications that rely on targeted adhesion. Here we introduce a new class of lubricant-infused surfaces that offer tunable bioactivity together with omniphobic properties by integrating biofunctional domains into the lubricant-infused layer. These novel surfaces promote targeted binding of desired species while simultaneously preventing nonspecific adhesion. To develop these surfaces, mixed self-assembled monolayers (SAMs) of aminosilanes and fluorosilanes were generated. Aminosilanes were utilized as coupling molecules for immobilizing capture ligands, and nonspecific adhesion of cells and proteins was prevented by infiltrating the fluorosilane molecules with a thin layer of a biocompatible fluorocarbon-based lubricant, thus generating biofunctional lubricant-infused surfaces. This method yields surfaces that (a) exhibit highly tunable binding of anti-CD34 and anti-CD144 antibodies and adhesion of endothelial cells, while repelling nonspecific adhesion of undesirable proteins and cells not only in buffer but also in human plasma or human whole blood, and (b) attenuate blood clot formation. Therefore, this straightforward and simple method creates biofunctional, nonsticky surfaces that can be used to optimize the performance of devices such as biomedical implants, extracorporeal circuits, and biosensors.

Tunable Microscale Porous Systems with Dynamic Liquid Interfaces

Solid microscale porous material systems have attracted more attention in recent years due to their various potential applications, such as energy source transportations, biomedical devices, wastewater treatments, phase separations, etc. However, such systems are still plagued with many issues including fouling, mechanical fragility, inability to self-heal, and low recyclability that restrict them for further industrial applications. Dynamic liquid-based microscale porous material systems, especially porous surfaces and membranes, provide a new opportunity for resolving these issues and possess many benefits, such as antifouling, slippery, transparent, recovery, self-healing, and recycling properties. This Concept is mainly concerned with how to obtain tunable microscale porous systems with dynamic liquid interfaces, and their applications from the surfaces to membranes. The authors hope this concept will attract interest of scientists in areas related to the rapid development and application of various liquid-based porous systems.