Search

Underwater adhesives are critical for many applications, including marine coatings, sealants, and medical devices. Research on natural underwater adhesives has shown that L-3,4-dihydroxyphenylalanine (DOPA) and amyloid nanostructures are vital to their adhesive abilities. The fusion of DOPA-containing chains and amyloid-forming peptides creates a new space for designing underwater adhesives capable of multi-surface adhesion. One critical question for this design is the interplay between the DOPA and amyloid-forming peptide regions. Here we investigate the effect of the sequence pattern of DOPA-containing chains on the aggregation conformation of conjugates. Discontinuous molecular dynamics simulations were performed for fourteen DOPA-amyloid conjugates with different sequence patterns along the DOPA-containing portion. The amyloid-forming portion is represented by KLVFFAE from the Aβ42 peptide. The structural properties of the DOPA-amyloid conjugates are characterised by the percentages of ordered secondary structures and residue-residue contact maps. The results showed that certain patterns of DOPA and glycine in the DOPA-containing tail allowed the KLVFFAE portions of the conjugates to form distinct ordered β-sheets, and the DOPA-containing portion and the KLVFFAE portion of the conjugates to remain separated both within the same chain and amongst different chains. Among the designs, the most promising sequences are KLVFFAE-G-YYGYYGYY (where Y represents DOPA) and KLVFFAE-G-YYYYGGGG. [ABSTRACT FROM AUTHOR]

Adhesives that can stick to multiple surface types in underwater and high moisture conditions are critical for various applications such as marine coatings, sealants, and medical devices. The analysis of natural underwater adhesives shows that L-3,4-dihydroxyphenylalanine (DOPA) and functional amyloid nanostructures are key components that contribute to the adhesive powers of these natural glues. The combination of DOPA and amyloid-forming peptides into DOPA-amyloid(-forming peptide) conjugates provides a new approach to design generic underwater adhesives. However, it remains unclear how the DOPA monomers may interact with amyloid-forming peptides and how these interactions may influence the adhesive ability of the conjugates. In this paper, we investigate the behavior of DOPA monomers, (glycine-DOPA)3 chains, and a KLVFFAE and DOPA-glycine chain conjugate in aqueous environments using molecular simulations. The DOPA monomers do not aggregate significantly at concentrations lower than 1.0M. Simulations of (glycine-DOPA)3 chains in water were done to examine the intra-molecular interactions of the chain, wherein we found that there were unlikely to be interactions detrimental to the adhesion process. After combining the alternating DOPA-glycine chain with the amyloid-forming peptide KLVFFAE into a single chain conjugate, we then simulated the conjugate in water and saw the possibility of both intra-chain folding and no chain folding in the conjugate. [ABSTRACT FROM AUTHOR]

Cone-jet electrospray has been proposed for various applications due to its ability to produce monodisperse droplets. The stable operation of the electrospray process is extremely important for quality assurance purposes, particularly for applications that require long-term operations. Typically, both the spray current and liquid meniscus shape are used to monitor the working condition of an electrospray. In practice, various factors (operational and environmental) could affect the electrospray operation. Thus, a new spray current control system was developed to improve the stability of a single capillary electrospray operated in the cone-jet mode. The new spray current control system has two control loops: the primary loop for spray current control and the auxiliary loop for meniscus image control. A simple method to characterize the shape of the liquid meniscus and to identify the operational mode of an electrospray was proposed and the performance of the proposed spray current control system was investigated. It was shown that, with the new control strategy, a single capillary electrospray system was able to continuously operate when encountering a severe perturbation (without the over-shooting caused by the previous control strategies) (i.e., the electrospray converged to the target spray current and liquid meniscus shape even when challenged by step perturbation on the spray liquid feeding flow rate). • A new strategy for the control of spray current in a single capillary electrospray is proposed. • The strategy consists of both primary and axillary loops for spray current and liquid meniscus controls, respectively. • A simple method to characterize the shape of liquid meniscus in the cone-jet mode is proposed. • The performance of new control system was evaluated. [ABSTRACT FROM AUTHOR]

Age-related functional decline of the nervous system is consistently observed, though cellular and molecular events responsible for this decline remain largely unknown. One of the most prevalent age-related functional declines is age-related hearing loss (presbycusis), a major cause of which is the loss of outer hair cells (OHCs) and spiral ganglion neurons. Previous studies have also identified an age-related functional decline in the medial olivocochlear (MOC) efferent system prior to age-related loss of OHCs. The present study evaluated the hypothesis that this functional decline of the MOC efferent system is due to age-related synaptic loss of the efferent innervation of the OHCs. To this end, we used a recently-identified transgenic mouse line in which the expression of yellow fluorescent protein (YFP), under the control of neuron-specific elements from the thy1 gene, permits the visualization of the synaptic connections between MOC efferent fibers and OHCs. In this model, there was a dramatic synaptic loss between the MOC efferent fibers and the OHCs in older mice. However, age-related loss of efferent synapses was independent of OHC status. These data demonstrate for the first time that age-related loss of efferent synapses may contribute to the functional decline of the MOC efferent system and that this synaptic loss is not necessary for age-related loss of OHCs. [ABSTRACT FROM AUTHOR]