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1.
Int J Pharm ; 609: 121218, 2021 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-34687813

RESUMO

Relationships between physicochemical properties of hydroxypropyl methylcellulose (HPMC) compacts and their in vitro mucoadhesive performances were investigated in this study. Some commercial grades of HPMC (K3, E3, E5, E50, K4M, E4M and K15M) were prepared into compacts, and their surface hydrophilicity and hydration behavior were characterized. The in vitro mucoadhesive performance was determined by the tensile strength between the compacts and different regions of mucosal membrane (buccal, sublingual, stomach, and intestine). Positive correlations were found between: (1) viscosity of HPMC compacts and contact angle in different simulated body fluids; (2) viscosity of HPMC compacts and in vitro mucoadhesive force; (3) contact angle and in vitro mucoadhesive force. The hydration increased with an increase in viscosity of HPMC compacts. The polar lipid content in mucosa was found to be an important factor affecting the mucoadhesion. Lower polar lipid amount in the mucosal membrane promoted the rate of mucoadhesive force with the increasing viscosity of HPMC. The mucoadhesive mechanism of various grades of HPMC compacts were studied using the thermodynamic analysis of Lifschitz-van der Waals (LW) interaction and Lewis acid-base (AB) interactions. The total free energy of adhesion (ΔGTOT) provided a prediction of an overall tendency of mucoadhesion, and deviated from the measured mucoadhesive force.


Assuntos
Metilcelulose , Adesividade , Interações Hidrofóbicas e Hidrofílicas , Derivados da Hipromelose , Resistência à Tração , Termodinâmica , Viscosidade
2.
J Exp Biol ; 224(20)2021 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-34581416

RESUMO

Many insects can climb smooth surfaces using hairy adhesive pads on their legs, mediated by tarsal fluid secretions. It was previously shown that a terrestrial beetle can even adhere and walk underwater. The naturally hydrophobic hairs trap an air bubble around the pads, allowing the hairs to make contact with the substrate as in air. However, it remained unclear to what extent such an air bubble is necessary for underwater adhesion. To investigate the role of the bubble, we measured the adhesive forces in individual legs of live but constrained ladybird beetles underwater in the presence and absence of a trapped bubble and compared these with its adhesion in air. Our experiments revealed that on a hydrophobic substrate, even without a bubble, the pads show adhesion comparable to that in air. On a hydrophilic substrate, underwater adhesion is significantly reduced, with or without a trapped bubble. We modelled the adhesion of a hairy pad using capillary forces. Coherent with our experiments, the model demonstrates that the wetting properties of the tarsal fluid alone can determine the ladybird beetles' adhesion to smooth surfaces in both air and underwater conditions and that an air bubble is not a prerequisite for their underwater adhesion. This study highlights how such a mediating fluid can serve as a potential strategy to achieve underwater adhesion via capillary forces, which could inspire artificial adhesives for underwater applications.


Assuntos
Adesivos , Besouros , Adesividade , Animais , Interações Hidrofóbicas e Hidrofílicas , Insetos , Molhabilidade
3.
Eur J Pharm Sci ; 166: 105965, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34375679

RESUMO

Oral drug delivery is often challenged with enzymatic degradation of drug molecules in the gastrointestinal tract and high first-pass metabolism, resulting in low bioavailability. Delivery of drug molecules via the oral cavity mucosa is considered a viable option to enhance bioavailability. One of the relatively new dosage forms for transmucosal drug delivery is the oral thin film (OTF) with mucoadhesive properties that offers several advantages over conventional dosage forms, including faster dissolution, higher patient compliance, and extended oral retention by reduced salivary washout. Mucoadhesive OTFs should have sufficient muco-adhesiveness as well as suitable mechanical properties for their best performance, thus such characterization is critical in the successful design and development of OTFs. However, there is currently no FDA or USP-recommended analytical procedure or standard available for evaluating adhesiveness and mechanical properties of mucoadhesive OTFs. Therefore, we aimed to develop a fast and reliable in vitro method capable of differentiating various OTFs in terms of their adhesive strengths using a texture analyzer. We found that an in vitro gel substrate composed of 4% w/v gellan gum and 2% w/v glycerin could be used to discriminate between the adhesive features of the tested film samples. Also, our studies show that the adhesion test parameters of 0.96 N target force, probe speed of 0.1 mm/s, holding time of 15 s, and conditioning medium volume of 200 µL while using the said substrate could successfully differentiate between the adhesion strength of the OTF samples. We further examined the film samples for their physicomechanical properties to obtain a tangible and practical range of mechanical values for pharmaceutical OTFs using the puncture test and folding endurance test. We found a breaking factor above 34.5 N/mm, elongation to puncture less than 5.55% and folding endurance of at least 50 folds can be used as a starting point when designing and manufacturing OTFs.


Assuntos
Sistemas de Liberação de Medicamentos , Preparações Farmacêuticas , Adesividade , Adesivos/metabolismo , Disponibilidade Biológica , Humanos , Mucosa Bucal/metabolismo , Preparações Farmacêuticas/metabolismo
4.
ACS Nano ; 15(9): 14598-14609, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34427447

RESUMO

At present, it is highly important to develop a simple and compatible nano delivery system for pesticides for foliar application, which can improve their insecticidal efficacy and resistance to adverse climates while reducing the environmental risks. Polyethylene glycol and 4,4-methylenediphenyl diisocyanate are used as hydrophilic soft and hydrophobic hard segments, respectively, for polymer self-assembly and polyurethane gelation in a nanoreactor. The nanocarrier synthesis and the pesticide loading are realized by a one-step integration procedure and suited well for hydrophobic active compounds. Modifying the molecular structure of the soft segment can adjust the flexibility of the nanocarriers and result in viscosity and deformation characteristics. After foliar spray application, the foliar flattening state of the nanogels increases the foliar protection area by 2.21 times and improves both pesticide exposure area and target contact efficiency. Concurrently, the flexibility and viscosity of the nanogels increase the washing resistance and the retention rate of the pesticide by approximately 80 times under continuous washing. The encapsulation of the nanogels reduces the foliar ultraviolet (UV) degradation and aquatic pesticide exposure, which increase the security of λ-cyhalothrine by 9.33 times. Moreover, the degradability of nanogels is beneficial for pesticide exposure and reducing pollution. This system has simple preparation, good properties, and environmental friendliness, making the nanocarriers promising for delivering pesticides.


Assuntos
Praguicidas , Adesividade , Nanogéis
5.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443344

RESUMO

Surface modification of electrodes with glycans was investigated as a strategy for modulating the development of electrocatalytic biofilms for microbial fuel cell applications. Covalent attachment of phenyl-mannoside and phenyl-lactoside adlayers on graphite rod electrodes was achieved via electrochemically assisted grafting of aryldiazonium cations from solution. To test the effects of the specific bio-functionalities, modified and unmodified graphite rods were used as anodes in two-chamber microbial fuel cell devices. Devices were set up with wastewater as inoculum and acetate as nutrient and their performance, in terms of output potential (open circuit and 1 kΩ load) and peak power output, was monitored over two months. The presence of glycans was found to lead to significant differences in startup times and peak power outputs. Lactosides were found to inhibit the development of biofilms when compared to bare graphite. Mannosides were found, instead, to promote exoelectrogenic biofilm adhesion and anode colonization, a finding that is supported by quartz crystal microbalance experiments in inoculum media. These differences were observed despite both adlayers possessing thickness in the nm range and similar hydrophilic character. This suggests that specific glycan-mediated bioaffinity interactions can be leveraged to direct the development of biotic electrocatalysts in bioelectrochemical systems and microbial fuel cell devices.


Assuntos
Fontes de Energia Bioelétrica , Polissacarídeos/química , Adesividade , Biofilmes , Eletrodos , Interações Hidrofóbicas e Hidrofílicas
6.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443357

RESUMO

In this work, we propose the utilization of scCO2 to impregnate ibuprofen into the mcl-PHA matrix produced by Pseudomonas chlororaphis subs. aurantiaca (DSM 19603). The biopolymer has adhesive properties, is biocompatible and has a melting temperature of 45 °C. Several conditions, namely, pressure (15 and 20 MPa) and impregnation time (30 min, 1 h and 3 h) were tested. The highest ibuprofen content (90.8 ± 6.5 mg of ibuprofen/gPHA) was obtained at 20 MPa and 40 °C, for 1 h, with an impregnation rate of 89 mg/(g·h). The processed mcl-PHA samples suffered a plasticization, as shown by the decrease of 6.5 °C in the Tg, at 20 MPa. The polymer's crystallinity was also affected concomitantly with the matrices' ibuprofen content. For all the impregnation conditions tested the release of ibuprofen from the biopolymer followed a type II release profile. This study has demonstrated that the mcl-PHA produced by P. chlororaphis has a great potential for the development of novel topical drug delivery systems.


Assuntos
Dióxido de Carbono/química , Portadores de Fármacos/química , Ibuprofeno/química , Poli-Hidroxialcanoatos/química , Adesividade , Liberação Controlada de Fármacos , Temperatura
7.
Molecules ; 26(16)2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34443456

RESUMO

Guanidinyl tryptophan derivatives TGN1, TGN2, TGN3, and TGN4 were synthesized, and these compounds were shown to possess in vitro inhibitory activity for amyloid aggregation in a previous study. Nevertheless, the influence of the TGN series of compounds on the binding and permeation behaviors of an Aß monomer to the cell membranes was not elucidated. In this study, we investigated the effect of compounds in the TGN series on the behavior of an Aß monomer regarding its toxicity toward the bilayer lipid membrane using molecular dynamics (MD) simulation. MD simulations suggest that TGN4 is a potential agent that can interfere with the movement of the Aß monomer into the membrane. The MM-GBSA result demonstrated that TGN4 exhibits the highest affinity to the Aß1-42 monomer but has the lowest affinity to the bilayer. Moreover, TGN4 also contributes to a decrease in the binding affinity between the Aß1-42 monomer and the POPC membrane. Regarding the results of the binding mode and conformational analyses, a high number of amino-acid residues were shown to provide the binding interactions between TGN4 and the Aß1-42 monomer. TGN4 also reduces the conformational transition of the Aß1-42 monomer by means of interacting with the monomer. The present study presents molecular-level insights into how the TGN series of compounds affect the membrane adsorption and the conformational transition of the Aß1-42 monomer, which could be valuable for the further development of new anti-Alzheimer agents.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides/química , Membrana Celular/metabolismo , Guanidina/uso terapêutico , Triptofano/uso terapêutico , Adesividade , Adsorção , Guanidina/química , Humanos , Ligantes , Bicamadas Lipídicas/química , Lipídeos/química , Modelos Moleculares , Simulação de Dinâmica Molecular , Fosfatidilcolinas/química , Conformação Proteica , Estrutura Secundária de Proteína , Triptofano/química , Água/química
8.
Colloids Surf B Biointerfaces ; 208: 112066, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34455316

RESUMO

Recently, smart hydrogels have attracted much attention for their abilities to respond to subtle changes in external and internal stimuli. Also, natural polysaccharide-based biomaterials are more appealing for their biocompatibility and biodegradability. However, limitations owing to their complex compositions and mechanisms, cumbersome synthetic routes, and single function call for a simple and effective strategy to develop novel multifunctional smart hydrogels. Herein, this developed work was achieved based on Bletilla striata polysaccharide (BSP), a kind of natural glucomannan with diverse bioactivities and biocompatibility, we fabricated a low-cost multifunctional hydrogel by oxidizing the catechol groups of carboxymethylated BSP(CBSP)-dopamine(DA) conjugate with adhesion, antioxidant, and pH-responsive properties. In this hydrogel system, CBSP as the backbone material, was negatively charged and conferred the hydrogel with pH sensitivity. The presence of catechol groups greatly enhanced the tissue adhesion and antioxidant capacities of the hydrogel. Meanwhile, the highly porous structure of hydrogel allowed berberine to be encapsulated and released to exhibit excellent and long-lasting antibacterial activity. In summary, the adhesion, antioxidant, pH-sensitive, and antibacterial multifunctional hydrogel showed massive potential in the biomedical field.


Assuntos
Antioxidantes , Hidrogéis , Adesividade , Antioxidantes/farmacologia , Concentração de Íons de Hidrogênio , Polissacarídeos/farmacologia
9.
ACS Appl Mater Interfaces ; 13(30): 36527-36537, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34313126

RESUMO

Tough adhesives with robust adhesion are desperately needed for biomedical and technological applications. However, it is extremely challenging to engineer tough and durable adhesives that are simple to make yet also exhibit strong underwater adhesion as well as tough bonding to diverse surfaces. Here, we report bioinspired elastomers based on water-immiscible polydiolcitrates, where their tough mechanical properties, robust underwater adhesion (80 kPa), and tough bonding performance (with an interfacial toughness >1000 J m-2 and a shear and tensile strength >0.5 MPa) to diverse solid materials (glass, ceramics, and steel) are actuated by the incorporation of trace amounts of additives. The additives could edit the polymer networks during the elastomer polymerization by dramatically regulating the cross-linking structures of covalent and reversible bonds, the length of polymer chains, and the hydrophobic and hydrophilic motifs, which markedly tuned the mechanical and adhesive properties of the bioelastomers. We also demonstrate versatile applications of the durable elastomers, as tough flexible joints for solid materials, superglue, tissue sealants, hemostatic dressing, and wound repair.


Assuntos
Adesivos/química , Citratos/química , Elastômeros/química , Polímeros/química , Adesividade , Animais , Bandagens , Módulo de Elasticidade , Mucosa Gástrica/metabolismo , Fígado/metabolismo , Teste de Materiais , Coelhos , Ratos , Resistência ao Cisalhamento , Suínos , Resistência à Tração , Dispositivos de Oclusão Vascular , Cicatrização/efeitos dos fármacos
10.
Mater Sci Eng C Mater Biol Appl ; 127: 112208, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34225860

RESUMO

Swelling is ubiquitous for traditional as-prepared hydrogels, but is unfavorable in many situations, especially biomedical applications, such as tissue engineering, internal wound closure, soft actuating and bioelectronics, and so forth. As the swelling of a hydrogel usually leads to a volume expansion, which not only deteriorates the mechanical property of the hydrogel but can bring about undesirable oppression on the surrounding tissues when applied in vivo. In contrast, anti-swelling hydrogels hardly alter their volume when applied in aqueous environment, therefore reserving the original mechanical performance and size-stability and facilitating their potential application. In the past decade, with the development of advanced hydrogels, quite a number of anti-swelling hydrogels with versatile functions have been developed by researchers to meet the practical applications well, through integrating anti-swelling property with certain performance or functionality, such as high strength, self-healing, injectability, adhesiveness, antiseptics, etc. However, there has not been a general summary with regard to these hydrogels. To promote the construction of anti-swelling hydrogels with desirable functionalities in the future, this review generalizes and analyzes the tactics employed so far in the design and manufacture of anti-swelling hydrogels, starting from the viewpoint of classical swelling theories. The review will provide a relatively comprehensive understanding of anti-swelling hydrogels and clues to researchers interested in this kind of materials to develop more advanced ones suitable for practical application.


Assuntos
Hidrogéis , Polímeros , Adesividade , Engenharia Tecidual
11.
Int J Nanomedicine ; 16: 4471-4480, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34234437

RESUMO

Background: Postoperative tissue adhesion is a major concern for most surgeons and is a nearly unpreventable complication after abdominal or pelvic surgeries. This study explored the use of sandwich-structured antimicrobial agents, analgesics, and human epidermal growth factor (hEGF)-incorporated anti-adhesive poly(lactic-co-glycolic acid) nanofibrous membranes for surgical wounds. Materials and Methods: Electrospinning and co-axial electrospinning techniques were utilized in fabricating the membranes. After spinning, the properties of the prepared membranes were assessed. Additionally, high-performance liquid chromatography and enzyme-linked immunosorbent assays were utilized in assessing the in vitro and in vivo liberation profiles of the pharmaceuticals and the hEGF from the membranes. Results: The measured data suggest that the degradable anti-adhesive membranes discharged high levels of vancomycin/ceftazidime, ketorolac, and hEGF in vitro for more than 30, 24, and 27 days, respectively. The in vivo assessment in a rat laparotomy model indicated no adhesion in the peritoneal cavity at 14 days post-operation, demonstrating the anti-adhesive capability of the sandwich-structured nanofibrous membranes. The nanofibers also released effective levels of vancomycin, ceftazidime, and ketorolac for more than 28 days in vivo. Histological examination revealed no adverse effects. Conclusion: The outcomes of this study implied that the anti-adhesive nanofibers with sustained release of antimicrobial agents, analgesics, and growth factors might offer postoperative pain relief and infection control, as well as promote postoperative healing of surgical wounds.


Assuntos
Analgésicos/farmacologia , Anti-Infecciosos/farmacologia , Família de Proteínas EGF/metabolismo , Membranas Artificiais , Nanofibras/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Adesividade/efeitos dos fármacos , Analgésicos/química , Animais , Anti-Infecciosos/química , Humanos , Ratos , Ferida Cirúrgica/fisiopatologia , Cicatrização/efeitos dos fármacos
12.
Langmuir ; 37(28): 8410-8416, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34213347

RESUMO

Strong, reversible, and self-cleaning adhesion in the toe pads of geckos allow the lizards to climb on a variety of vertical and inverted surfaces, regardless of the surface conditions, whether hydrophobic or hydrophilic, smooth or tough, wet or dry, clean or dirty. Development of synthetic gecko-inspired surfaces has drawn a great attention over the past two decades. Despite many external-stimuli responsive mechanisms (i.e., thermal, electrical, magnetic) have been successfully demonstrated, smart adhesives controlled by light signals still substantially lag behind. Here, in this report, we integrate tetramethylpiperidinyloxyl (TEMPO)-doped polydopamine (PDA), namely, TDPDA, with PDMS micropillars using a template-assisted casting method, to achieve both improved adhesion and self-cleaning performances. To the best of our knowledge, this is the first report on PDA being used as a doping nanoparticle in bioinspired adhesive surfaces to achieve highly efficient self-cleaning controllable by light signals. Notably, the adhesion of the 5% TDPDA-PDMS sample is ∼688.75% higher than that of the pure PDMS at the individual pillar level, which helps to explain the highly efficient self-cleaning mechanism. The sample surfaces (named TDPDA-PDMS) can efficiently absorb 808 nm wavelength of light and heat up from 25 °C to 80.9 °C in 3 min with NIR irradiation. The temperature rise causes significant reduction of adhesion, which results in outstanding self-cleaning rate of up to 55.8% within five steps. The exploration of the photoenabled switching mechanism with outstanding sensitivity may bring the biomimetic smart surfaces into a new dimension, rendering varied applications, e.g., in miniaturized climbing robot, artificial intelligence programmable manipulation/assembly/filtration, active self-cleaning solar panels, including high output sensors and devices in many engineering and biomedical frontiers.


Assuntos
Inteligência Artificial , Lagartos , Adesividade , Adesivos , Animais , Biomimética
13.
Nat Commun ; 12(1): 4419, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34285208

RESUMO

Electroadhesion, i.e., adhesion induced by an electric field, occurs between non-sticky cationic and anionic hydrogels. Here, we demonstrate electroadhesion between cationic gels and animal (bovine) tissues. When gel and tissue are placed under an electric field (DC, 10 V) for 20 s, the pair strongly adhere, and the adhesion persists indefinitely thereafter. Applying the DC field with reversed polarity eliminates the adhesion. Electroadhesion works with the aorta, cornea, lung, and cartilage. We demonstrate the use of electroadhesion to seal cuts or tears in tissues or model anionic gels. Electroadhered gel-patches provide a robust seal over openings in bovine aorta, and a gel sleeve is able to rejoin pieces of a severed gel tube. These studies raise the possibility of using electroadhesion in surgery while obviating the need for sutures. Advantages include the ability to achieve adhesion on-command, and moreover the ability to reverse this adhesion in case of error.


Assuntos
Hidrogéis/administração & dosagem , Procedimentos Cirúrgicos sem Sutura/métodos , Ferimentos e Lesões/cirurgia , Testes de Impedância Acústica , Adesividade , Animais , Aorta/cirurgia , Bovinos , Estudos de Viabilidade , Humanos , Hidrogéis/química , Teste de Materiais , Resistência ao Cisalhamento
14.
ACS Appl Mater Interfaces ; 13(28): 33371-33382, 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34236852

RESUMO

We report on robust silk fibroin (SF) gels fabricated by incorporating cellulose nanocrystals (SF/CNC) as a "tough" unit and photopolymerization of acrylamide as an "elastic" segment. The addition of CNC affects the refolding process of SF molecules controlled by nucleation via templating, resulting in a stable mesoscopic structure. The gel shows robust mechanical stability (88.8% of initial stress after 1000 compression cycles) and excellent adhesion to various materials. The connected gel can recover its ionic conductivity within 20 s and be stretched to a maximum strain of 498% after healing for 10 h with an efficiency of 95.2%. This multifunctional gel sensor can sensitively detect different toxic gases and small-scale and large-scale human motions in real-time. Its sensitivity is calculated as GF = 3.84 at 0-200% strain. Especially, the gel with 5 wt % thermochromic pigments as a visual temperature indicator can quickly reflect abnormal human body temperature according to the color change. Therefore, the strategy shows potential applications in flexible electrodes, biomimetic sensors, and visual biosensors.


Assuntos
Técnicas Biossensoriais/métodos , Fibroínas/química , Hidrogéis/química , Resinas Acrílicas/química , Adesividade , Temperatura Corporal , Celulose/química , Força Compressiva , Módulo de Elasticidade , Condutividade Elétrica , Gases/análise , Humanos , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Movimento (Física) , Nanopartículas/química , Dispositivos Eletrônicos Vestíveis
15.
Compr Rev Food Sci Food Saf ; 20(4): 3838-3857, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34118135

RESUMO

Excessive bitterness, pastiness, and adhesiveness are the main organoleptic and textural defects of dry-cured ham, which often cause a lot of financial losses to manufacturers and seriously damage the quality of the product. These sensory and textural defects are related to the protein degradation of dry-cured ham. Proteomics shows great potential to improve our understanding of the molecular mechanism of sensory and textural defects and identify biomarkers for monitoring their quality traits. This review presents some of the major achievements and considerations in organoleptic and textural defects of dry-cured ham by proteomics analysis in the recent decades and gives an overview about how to correct sensory and textural defects of dry-cured ham. Proteomics reveals that muscle proteins derived from myofibril and cytoskeleton and involved in metabolic enzymes and oxygen transport have been identified as potential biomarkers in defective dry-cured ham. Relatively high residual activities of cathepsin B and L are responsible for the excessive degradation of these protein biomarkers in defective dry-cured ham. Ultrasound-assisted mild thermal or high-pressure treatment shows a good correction for the organoleptic and textural defects of dry-cured ham by changing microstructure and conformation of muscle proteins by accelerating degradation of proteins and polypeptides into free amino acids.


Assuntos
Produtos da Carne , Carne de Porco , Adesividade , Produtos da Carne/análise , Proteínas Musculares , Proteômica
16.
Carbohydr Polym ; 268: 118240, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34127222

RESUMO

Recently, flexible and wearable sensors assembled from conductive hydrogels have attracted widespread attention. However, it is still a great challenge to make hydrogels with sufficient mechanical properties, self-adhesiveness and strain sensitivity. Here, a strong, tough, and self-adhesive hydrogel is successfully fabricated by a one-pot method, which introducing chitosan and 2-acrylamido-2-methylpropane sulfonic acid into the polyacrylamide network. The hydrogels exhibited adhesion (the peel strength reaches 798 N/m), mechanical property (The breaking strength and strain can reach 111 kPa and 2839%) and electrical conductivity (conductivity up to 0.0848 S/cm), which are suitable for wearable epidermal sensors. Besides, the hydrogels also possessed transparency. Therefore, this work would provide a novel insight on the fabrication of multi-functional self-adhesive hydrogel sensors.


Assuntos
Quitosana/química , Hidrogéis/química , Monitorização Fisiológica/métodos , Dispositivos Eletrônicos Vestíveis , Acrilamidas/química , Adesividade , Alcanossulfonatos/química , Força Compressiva , Módulo de Elasticidade , Condutividade Elétrica , Humanos , Teste de Materiais , Monitorização Fisiológica/instrumentação , Movimento (Física) , Polimerização , Resistência à Tração , Tecnologia sem Fio
17.
Philos Trans A Math Phys Eng Sci ; 379(2203): 20200289, 2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34148419

RESUMO

Atomic force microscopy (AFM) studies of living biological cells is one of main experimental tools that enable quantitative measurements of deformation of the cells and extraction of information about their structural and mechanical properties. However, proper modelling of AFM probing and related adhesive contact problems are of crucial importance for interpretation of experimental data. The Johnson-Kendall-Roberts (JKR) theory of adhesive contact has often been used as a basis for modelling of various phenomena including cell-cell interactions. However, strictly speaking the original JKR theory is valid only for contact of isotropic linearly elastic spheres, while the cell membranes are often prestressed. For the first time, effects caused by molecular adhesion for living cells are analytically studied taking into account the mechanical properties of cell membranes whose stiffness depends on the level of the tensile prestress. Another important question is how one can extract the work of adhesion between the probe and the cell. An extended version of the Borodich-Galanov method for non-direct extraction of elastic and adhesive properties of contacted materials is proposed to apply to experiments of cell probing. Evidently, the proposed models of adhesive contact for cells with prestressed membranes do not cover all types of biological cells because the structure and properties of the cells may vary considerably. However, the obtained results can be applied to many types of smooth cells and can be used to describe initial stages of contact and various other processes when effects of adhesion are of crucial importance. This article is part of a discussion meeting issue 'A cracking approach to inventing new tough materials: fracture stranger than friction'.


Assuntos
Adesão Celular/fisiologia , Membrana Celular/fisiologia , Adesividade , Fenômenos Biomecânicos , Módulo de Elasticidade/fisiologia , Humanos , Conceitos Matemáticos , Microscopia de Força Atômica/métodos , Modelos Biológicos , Estresse Mecânico , Propriedades de Superfície
18.
Molecules ; 26(9)2021 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-34064401

RESUMO

Hydrogel adhesives are attractive for applications in intelligent soft materials and tissue engineering, but conventional hydrogels usually have poor adhesion. In this study, we designed a strategy to synthesize a novel adhesive with a thin hydrogel adhesive layer integrated on a tough substrate hydrogel. The adhesive layer with positive charges of ammonium groups on the polymer backbones strongly bonds to a wide range of nonporous materials' surfaces. The substrate layer with a dual hydrogen bond system consists of (i) weak hydrogen bonds between N,N-dimethyl acrylamide (DMAA) and acrylic acid (AAc) units and (ii) strong multiple hydrogen bonds between 2-ureido-4[1H]-pyrimidinone (UPy) units. The dual hydrogen-bond network endowed the hydrogel adhesives with unique mechanical properties, e.g., toughness, highly stretchability, and insensitivity to notches. The hydrogel adhesion to four types of materials like glass, 316L stainless steel, aluminum, Al2O3 ceramic, and two biological tissues including pig skin and pig kidney was investigated. The hydrogel bonds strongly to dry solid surfaces and wet tissue, which is promising for biomedical applications.


Assuntos
Hidrogéis/química , Acrilamidas/química , Acrilatos/química , Adesividade , Animais , Ligação de Hidrogênio , Suínos
19.
Sensors (Basel) ; 21(11)2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34063792

RESUMO

Electroconductive hydrogels with stimuli-free self-healing and self-recovery (SELF) properties and high mechanical strength for wearable strain sensors is an area of intensive research activity at the moment. Most electroconductive hydrogels, however, consist of static bonds for mechanical strength and dynamic bonds for SELF performance, presenting a challenge to improve both properties into one single hydrogel. An alternative strategy to successfully incorporate both properties into one system is via the use of stiff or rigid, yet dynamic nano-materials. In this work, a nano-hybrid modifier derived from nano-chitin coated with ferric ions and tannic acid (TA/Fe@ChNFs) is blended into a starch/polyvinyl alcohol/polyacrylic acid (St/PVA/PAA) hydrogel. It is hypothesized that the TA/Fe@ChNFs nanohybrid imparts both mechanical strength and stimuli-free SELF properties to the hydrogel via dynamic catecholato-metal coordination bonds. Additionally, the catechol groups of TA provide mussel-inspired adhesion properties to the hydrogel. Due to its electroconductivity, toughness, stimuli-free SELF properties, and self-adhesiveness, a prototype soft wearable strain sensor is created using this hydrogel and subsequently tested.


Assuntos
Hidrogéis , Dispositivos Eletrônicos Vestíveis , Adesividade , Polissacarídeos , Taninos
20.
Nat Commun ; 12(1): 3402, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099677

RESUMO

A major deficit in tissue engineering strategies is the lack of materials that promote angiogenesis, wherein endothelial cells from the host vasculature invade the implanted matrix to form new blood vessels. To determine the material properties that regulate angiogenesis, we have developed a microfluidic in vitro model in which chemokine-guided endothelial cell sprouting into a tunable hydrogel is followed by the formation of perfusable lumens. We show that long, perfusable tubes only develop if hydrogel adhesiveness and degradability are fine-tuned to support the initial collective invasion of endothelial cells and, at the same time, allow for matrix remodeling to permit the opening of lumens. These studies provide a better understanding of how cell-matrix interactions regulate angiogenesis and, therefore, constitute an important step towards optimal design criteria for tissue-engineered materials that require vascularization.


Assuntos
Matriz Extracelular/química , Hidrogéis/química , Neovascularização Fisiológica , Engenharia Tecidual/métodos , Adesividade , Dextranos/química , Células Endoteliais da Veia Umbilical Humana , Humanos , Dispositivos Lab-On-A-Chip , Metacrilatos/química , Sulfonas/química , Engenharia Tecidual/instrumentação
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