Editorial: Electrospinning of Bioinspired Materials and Structures for Bioengineering and Advanced Biomedical Applications

The Research Topic “Electrospinning of Bioinspired Materials and Structures for Bioengineering and Advanced Biomedical Applications” includes submissions that relate to the “Biomaterials” and “Bionics and Biomimetics” sections of Frontiers in Bioengineering and Biotechnology. The collection aims to provide an overview of how electrospinning, inspired by nature, can reproduce the hierarchical structure and biomechanical properties of biological tissues, ranging from the nanoscale to the macroscale. The development of such innovative nanofibrous structures requires the improvement of both functionalization and biofabrication strategies, to enhance the scaffold bioactivity and to drive cells in the regeneration of the extracellular matrix (ECM) of the target tissues of interest. Recent technological advances have given rise to the availability of intelligent and smart biomaterials for the regeneration of innovative procedures for manufacturing nanometric structures, and methods for assembling multiscale hierarchical structures. Furthermore, imaging has improved considerably in the last few years, allowing multimodal imaging with nanometric resolution

Hierarchical fibrous structures for muscle-inspired soft-actuators:A review

Inspired by Nature, one of the most ambitious challenge in soft robotics is to design actuators capable of reaching performances comparable to the skeletal muscles. Considering the perfectly balanced features of natural muscular tissue in terms of linear contraction, force‐to‐weight ratio, scalability and morphology, scientists have been working for many years on mimicking this structure. Focusing on the biomimicry, this review investigates the state‐of‐the‐art of synthetic fibrous, muscle‐inspired actuators that, aiming to enhance their mechanical performances, are hierarchically designed from the nanoscale up to the macroscale. In particular, this review focuses on those hierarchical fibrous actuators that enhance their biomimicry employing a linear contraction strategy, closely resembling the skeletal muscles actuation system. The literature analysis shows that bioinspired artificial muscles, developed up to now, only in part comply with skeletal ones. The manipulation and control of the matter at the nanoscale allows to realize ordered structures, such as nanofibers, used as elemental actuators characterized by high strains but moderate force levels. Moreover, it can be foreseen that scaling up the nanostructured materials into micro‐ and macroscale hierarchical structures, it is possible to realize linear actuators characterized by suitable levels of force and displacement

MORPHOLOGICALLY BIO-INSPIRED HIERARCHICAL NYLON 6,6 ELECTROSPUN STRUCTURES FOR SOFT-ROBOTICS APPLICATIONS

The last decades have seen an increasing attention on a new, ground-breaking field, soft-robotics [1]. Soft-robotics tries to overcome the limits of classical rigid robots, developing bioinspired structures with compliant and soft materials. Skeletal muscle is a biological, hierarchically arranged fibrous structure (Fig A), suitable to inspire innovative soft actuators. The possibility to mimic muscles and soft tissues has been demonstrated through the use of the electrospinning technique [2]. The aim of the present study was to develop and characterize innovative muscle-inspired, hierarchically arranged electrospun structures made of Nylon 6,6 for soft-robotics applications. In order to mimic skeletal muscle myofibrils [3], mats of aligned Nylon 6,6 nanofibers were electrospun on a rotating drum collector. To reproduce skeletal muscle fibers and fascicles morphology [3], the mats were cut in stripes and wrapped up on the drum, producing bundles of axially aligned nanofibers. The bundles were then pulled out from the drum, obtaining ring-shaped bundles. To mimic a whole skeletal muscle with its epimysium membrane [3], 2-levels hierarchical structure was developed (Fig B). Several bundles were aligned and packed together using a nanofibrous sheath produced through an innovative electrospinning setup [4]. Finally, in order to mimic also the skeletal muscle fascicles and perimysium [3], a 3-levels hierarchical structure was obtained by grouping together three 2-levels hierarchical structures, produced as previously described, with an additional electrospun sheath (Fig C). A morphological investigation of the different electrospun structures was carried out with scanning electron microscopy (SEM) and high-resolution x-ray tomography (XCT). The alignment of the nanofibers of the electrospun sheaths and the internal bundles, was quantified with a previously validated methodology [5]. The bundles and the 2-levels hierarchical structures were also mechanically characterized with a monotonic tensile test. The level of alignment of the nanofibers in the sheaths has proved to be tuneable by modifying the electrospinning parameters. The electrospun sheaths are also capable to tighten the structures wrapped inside, reducing their cross-sectional area and improving the apparent mechanical strength and stiffness. The high-resolution imaging confirmed that the mean diameters of the different hierarchical structures were comparable to the corresponding structures of biological skeletal muscle [3]. The directionality analysis on both bundles and sheaths nanofibers showed comparable levels of alignment with corresponding skeletal muscles fibrous tissues [3]. The mechanical test on the structures revealed a non-linear behaviour typical of soft tissue. The 2- levels hierarchical structures showed mechanical properties roughly proportional to the number of single bundles incorporated (with a possible underestimation of the ultimate strength, due to a stress concentration at the grips). In conclusion, this innovative electrospinning approach to produce hierarchically-arranged structures will be suitable to develop muscle-inspired assemblies. We will explore the possibility of incorporating adequate contracting ability so as to build soft actuators

The Effect of Keratinized Mucosa on Peri-Implant Health and Patient-Reported Outcome Measures: A Systematic Review and Meta-Analysis

Objectives: The aim of this systematic review was to analyze the effect of keratinized mucosa (KM) on different peri-implant health-related parameters and on patient-reported outcome measures (PROMs). Material and methods: Randomized controlled trials, cohort, cross-sectional and case-control human studies with a follow-up period of at least 6 months comparing two groups of patients with presence or absence of KM, or with KM < 2 mm or & GE;2 mm were included. Primary outcomes were implant failures, PROMs and BoP (BoP/mBI). Additional outcomes were PPD, plaque accumulation (mPI/PI), gingival inflammation (GI/mGI), marginal bone loss (MBL), soft tissue recession (REC) and biological complications. Results: Fifteen studies were included (one RCT, two cohort prospective and twelve cross-sectional). Meta-analysis was performed for cross-sectional studies. Implant failure and complications were not presented as outcome measures, and five studies analyzed PROMs. Results from the meta-analysis reported no evidence of any statistical significant difference between groups in PPD, BoP and MBL, while a statistical significant difference in GI/BI, PI and REC was present in favor of the group with KW & GE; 2 mm. More biological complications were present in the group with no KM/KM < 2 mm but few cases were present to draw any conclusions. Although a meta-analysis could not be performed, a consistent trend toward the worst pain/discomfort in KM < 2 mm was observed. Conclusions: No clear evidence was found supporting the role of KM in peri-implant health and PROMs, even if more plaque and marginal inflammation were present in the KM < 2 mm group. Clinical relevance: KM could have a role in patients with erratic maintenance and patient comfort

Multimorbidity burden and dementia risk in older adults : The role of inflammation and genetics

Funding: Swedish National study on Aging and Care; Ministry of Health and Social Affairs; Swedish Research Council, Grant/Award Number: 2016-00981; Swedish Research Council for Health,Working Life andWelfare, Grant/Award Number: 2017-01764; Italian Ministry of Health, Grant/Award Number: PE-2016-02364885We investigate dementia risk in older adults with different disease patterns and explore the role of inflammation and apolipoprotein E (APOE) genotype. A total of 2,478 dementia-free participants with two or more chronic diseases (ie, multimorbidity) part of the Swedish National study on Aging and Care in Kungsholmen (SNAC-K) were grouped according to their multimorbidity patterns and followed to detect clinical dementia. The potential modifier effect of C-reactive protein (CRP) and apolipoprotein E (APOE) genotype was tested through stratified analyses. People with neuropsychiatric, cardiovascular, and sensory impairment/cancer multimorbidity had increased hazards for dementia compared to the unspecific (Hazard ration (HR) 1.66, 95% confidence interval [CI] 1.13-2.42; 1.61, 95% CI 1.17-2.29; 1.32, 95% CI 1.10-1.71, respectively). Despite the lack of statistically significant interaction, high CRP increased dementia risk within these patterns, and being APOE ε4 carriers heightened dementia risk for neuropsychiatric and cardiovascular multimorbidity. Individuals with neuropsychiatric, cardiovascular, and sensory impairment/cancer patterns are at increased risk for dementia and APOE ε4, and inflammation may further increase the risk. Identifying such high-risk groups might allow tailored interventions for dementia prevention

Multimorbidity Patterns and 6-Year Risk of Institutionalization in Older Persons: The Role of Social Formal and Informal Care

Abstract Objectives The aim was to evaluate patterns of multimorbidity that increase the risk of institutionalization in older persons, also exploring the potential buffering effect of formal and informal care. Design Prospective cohort study. Setting and Participants The population-based Swedish National study on Aging and Care in Kungsholmen, Stockholm, Sweden. Measures In total, 2571 community-dwelling older adults were grouped at baseline according to their underlying multimorbidity patterns, using a fuzzy c-means cluster algorithm, and followed up for 6 years to test the association between multimorbidity patterns and institutionalization. Results Six patterns of multimorbidity were identified: psychiatric diseases; cardiovascular diseases, anemia, and dementia; metabolic and sleep disorders; sensory impairments and cancer; musculoskeletal, respiratory, and gastrointestinal diseases; and an unspecific pattern including diseases of which none were overrepresented. In total, 110 (4.3%) participants were institutionalized during the follow-up, ranging from 1.7% in the metabolic and sleep disorders pattern to 8.4% in the cardiovascular diseases, anemia, and dementia pattern. Compared with the unspecific pattern, only the cardiovascular diseases, anemia, dementia pattern was significantly associated with institutionalization [relative risk ratio (RRR) = 2.23; 95% confidence interval (CI) 1.07‒4.65)], after adjusting for demographic characteristics and disability status at baseline. In stratified analyses, those not receiving formal care in the psychiatric diseases pattern (RRR 3.34; 95% CI 1.20‒9.32) and those not receiving formal or informal care in the 'cardiovascular diseases, anemia, dementia' pattern (RRR 2.99; 95% CI 1.20‒7.46; RRR 2.79; 95% CI 1.16‒6.71, respectively) had increased risks of institutionalization. Conclusions and Implications Older persons suffering from specific multimorbidity patterns have a higher risk of institutionalization, especially if they lack formal or informal care. Interventions aimed at preventing the clustering of diseases could reduce the associated burden on residential long-term care. Formal and informal care provision may be effective strategies in reducing the risk of institutionalization

Search for Neutral Heavy Leptons Produced in Z Decays

Weak isosinglet Neutral Heavy Leptons ($\nu_m$) have been searched for using data collected by the DELPHI detector corresponding to $3.3\times 10^{6}$ hadronic~Z$^{0}$ decays at LEP1. Four separate searches have been performed, for short-lived $\nu_m$ production giving monojet or acollinear jet topologies, and for long-lived $\nu_m$ giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio $BR($Z$^0\rightarrow \nu_m \overline{\nu})$ of about $1.3\times10^{-6}$ at 95\% confidence level for $\nu_m$ masses between 3.5 and 50 GeV/$c^2$. Outside this range the limit weakens rapidly with the $\nu_m$ mass. %Special emphasis has been given to the search for monojet--like topologies. One event %has passed the selection, in agreement with the expectation from the reaction: %$e^+e^- \rightarrow\ell \bar\ell \nu\bar\nu$. The results are also interpreted in terms of limits for the single production of excited neutrinos