Effect of different D-amino acids on biofilm formation of mixed microorganisms

This study aimed to determine the effects of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine on biofilm formation of mixed microorganisms. Results showed that, in the attachment stage, D-amino acids caused significant reduction in adhesion efficiency of mixed microorganisms to membrane surface. Moreover, D-amino acids have a promoting effect on the reversible adhesion of mixed microorganisms. The addition of D-amino acid generally inhibited the biofilm biomass, of which D-tyrosine has the best inhibition effect. With the effect of D-tyrosine, D-aspartic acid, D-tryptophan and D-leucine, the protein in extracellular polymeric substance (EPS) decreased by 8.21%, 7.65%, 3.51% and 11.31%, respectively. The carbohydrates in EPS decreased by 29.53%, 21.44%, 14.60% and 10.54%, respectively. The results of excitation-emission matrix spectra (EEMs) suggested that the structural properties of the tyrosine-like proteins, tryptophan-like protein and humic-like acid might have changed by the D-amino acids.

Hydrogel tapes for fault-tolerant strong wet adhesion

Fast and strong bio-adhesives are in high demand for many biomedical applications, including closing wounds in surgeries, fixing implantable devices, and haemostasis. However, most strong bio-adhesives rely on the instant formation of irreversible covalent crosslinks to provide strong surface binding. Repositioning misplaced adhesives during surgical operations may cause severe secondary damage to tissues. Here, we report hydrogel tapes that can form strong physical interactions with tissues in seconds and gradually form covalent bonds in hours. This timescale-dependent adhesion mechanism allows instant and robust wet adhesion to be combined with fault-tolerant convenient surgical operations. Specifically, inspired by the catechol chemistry discovered in mussel foot proteins, we develop an electrical oxidation approach to controllably oxidize catechol to catecholquinone, which reacts slowly with amino groups on the tissue surface. We demonstrate that the tapes show fast and reversible adhesion at the initial stage and ultrastrong adhesion after the formation of covalent linkages over hours for various tissues and electronic devices. Given that the hydrogel tapes are biocompatible, easy to use, and robust for bio-adhesion, we anticipate that they may find broad biomedical and clinical applications.

Hydrogel tapes for fault-tolerant strong wet adhesion

Fast and strong bio-adhesives are in high demand for many biomedical applications, including closing wounds in surgeries, fixing implantable devices, and haemostasis. However, most strong bio-adhesives rely on the instant formation of irreversible covalent crosslinks to provide strong surface binding. Repositioning misplaced adhesives during surgical operations may cause severe secondary damage to tissues. Here, we report hydrogel tapes that can form strong physical interactions with tissues in seconds and gradually form covalent bonds in hours. This timescale-dependent adhesion mechanism allows instant and robust wet adhesion to be combined with fault-tolerant convenient surgical operations. Specifically, inspired by the catechol chemistry discovered in mussel foot proteins, we develop an electrical oxidation approach to controllably oxidize catechol to catecholquinone, which reacts slowly with amino groups on the tissue surface. We demonstrate that the tapes show fast and reversible adhesion at the initial stage and ultrastrong adhesion after the formation of covalent linkages over hours for various tissues and electronic devices. Given that the hydrogel tapes are biocompatible, easy to use, and robust for bio-adhesion, we anticipate that they may find broad biomedical and clinical applications.

Strategies for Interfering With Bacterial Early Stage Biofilms

Biofilm-related bacteria show high resistance to antimicrobial treatments, posing a remarkable challenge to human health. Given bacterial dormancy and high expression of efflux pumps, persistent infections caused by mature biofilms are not easy to treat, thereby driving researchers toward the discovery of many anti-biofilm molecules that can intervene in early stage biofilms formation to inhibit further development and maturity. Compared with mature biofilms, early stage biofilms have fragile structures, vigorous metabolisms, and early attached bacteria are higher susceptibility to antimicrobials. Thus, removing biofilms at the early stage has evident advantages. Many reviews on anti-biofilm compounds that prevent biofilms formation have already been done, but most of them are based on compound classifications to introduce anti-biofilm effects. This review discusses the inhibitory effects of anti-biofilm compounds on early stage biofilms formation from the perspective of the mechanisms of action, including hindering reversible adhesion, reducing extracellular polymeric substances production, interfering in the quorum sensing, and modifying cyclic di-GMP. This information can be exploited further to help researchers in designing new molecules with anti-biofilm activity.

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature

Highlights Shape memory self-soldering tape used as conductive interconnecting material. Perfect shape and conductivity memory performance and anti-fatigue performance. Reversible strong-to-weak adhesion switched by temperature. Abstract With practical interest in the future applications of next-generation electronic devices, it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements. Herein, we design highly stretchable shape memory self-soldering conductive (SMSC) tape with reversible adhesion switched by temperature, which is composed of silver particles encapsulated by shape memory polymer. SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%. It also exhibits an initial conductivity of 2772 S cm−1 and a maximum tensile strain of ~ 100%. The maximum conductivity could be increased to 5446 S cm−1 by decreasing the strain to 17%. Meanwhile, SMSC tape can easily realize a heating induced reversible strong-to-weak adhesion transition for self-soldering circuit. The combination of stable conductivity, excellent shape memory performance, and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously. This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.

Applications of Bioinspired Reversible Dry and Wet Adhesives: A Review

Bioinspired adhesives that emulate the unique dry and wet adhesion mechanisms of living systems have been actively explored over the past two decades. Synthetic bioinspired adhesives that have recently been developed exhibit versatile smart adhesion capabilities, including controllable adhesion strength, active adhesion control, no residue remaining on the surface, and robust and reversible adhesion to diverse dry and wet surfaces. Owing to these advantages, bioinspired adhesives have been applied to various engineering domains. This review summarizes recent efforts that have been undertaken in the application of synthetic dry and wet adhesives, mainly focusing on grippers, robots, and wearable sensors. Moreover, future directions and challenges toward the next generation of bioinspired adhesives for advanced industrial applications are described.