Cell-based tissue reconstruction is an important field of regenerative medicine. Stem and progenitor cells derived from tooth-associated tissues have strong regeneration potential. However, their in vivo application requires the development of novel scaffolds that will provide a suitable three-dimensional (3D) environment allowing not only the survival of the cells but eliciting their proliferation and differentiation. Our aim was to study the viability and differentiation capacity of periodontal ligament cells (PDLCs) cultured on recently developed biocompatible and biodegradable poly(aspartamide) (PASP)-based hydrogels. Viability and behavior of PDLCs were investigated on PASP-based hydrogels possessing different chemical, physical and mechanical properties. Based on our previous results, the effect of thiol group density in the polymer matrix on cell viability, morphology and differentiation ability is in the focus of our article. The chemical composition and 3D structures of the hydrogels were determined by FT Raman spectroscopy and Scanning Electron Microscopy. Morphology of the cells was examined by phase contrast microscopy. To visualize cell growth and migration patterns through the hydrogels, two-photon microscopy were utilized. Cell viability analysis was performed according to a standardized protocol using WST-1 reagent. PDLCs were able to attach and grow on PASP-based hydrogels. An increase in gel stiffness enhanced adhesion and proliferation of the cells. However, the highest population of viable cells was observed on the PASP gels containing free thiol groups. The presence of thiol groups does not only enhance viability but also facilitates the osteogenic direction of the differentiating cells. These cell-gel structures seem to be highly promising for cell-based tissue reconstruction purposes in the field of regenerative medicine.

Background Current hand hygiene guidelines do not provide recommendations on a specific volume for the clinical hand rubbing procedure. According to recent studies volume should be adjusted in order to achieve complete coverage. However, hand size is a parameter that highly influences the hand coverage quality when using alcohol-based handrubs (ABHR). The purpose of this study was to establish a quantitative correlation between applied ABHR volume and achieved hand coverage. Method ABHR based hand hygiene events were evaluated utilizing a digital health device, the Semmelweis hand hygiene system with respect to coverage achieved on the skin surface. Medical students and surgical residents (N = 356) were randomly selected and given predetermined ABHR volumes. Additionally, hand sizes were calculated using specialized software developed for this purpose. Drying time, ABHR volume awareness, as well spillage awareness were documented for each hand hygiene event. Results Hand coverage achieved during a hand hygiene event strongly depends on the applied ABHR volume. At a 1 ml dose, the uncovered hand area was approximately 7.10%, at 2 ml it decreased to 1.68%, and at 3 ml it further decreased to 1.02%. The achieved coverage is strongly correlated to hand size, nevertheless, a 3 ml applied volume proved sufficient for most hand hygiene events (84%). When applying a lower amount of ABHR (1.5 ml), even people with smaller hands failed to cover their entire hand surface. Furthermore, a 3 ml volume requires more than the guideline prescribed 20–30 s to dry. In addition, results suggest that drying time is not only affected by hand size, but perhaps other factors may be involved as well (e.g., skin temperature and degree of hydration). ABHR volumes of 3.5 ml or more were inefficient, as the disinfectant spilled while the additional rubbing time did not improve hand coverage. Conclusions Hand sizes differ a lot among HCWs. After objectively measuring participants, the surface of the smallest hand was just over half compared to the largest hand (259 cm2 and 498 cm2, respectively). While a 3 ml ABHR volume is reasonable for medium-size hands, the need for an optimized volume of handrub for each individual is critical, as it offers several advantages. Not only it can ensure adequate hand hygiene quality, but also prevent unnecessary costs. Bluntly increasing the volume also increases spillage and therefore waste of disinfectant in the case of smaller hands. In addition, adherence could potentially decrease due to the required longer drying time, therefore, adjusting the dosage according to hand size may also increase the overall hand hygiene compliance.

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In this work two types of biodegradable polysuccinimide-based, electrospun fibrous membranes are presented. One contains disulfide bonds exhibiting a shorter (3 days) in vivo biodegradation time, while the other one has alkyl crosslinks and a longer biodegradation time (more than 7 days). According to the mechanical measurements, the tensile strength of the membranes is comparable to those of soft the connective tissues and visceral tissues. Furthermore, the suture retention test suggests, that the membranes would withstand surgical handling and in vivo fixation. The in vivo biocompatibility study demonstrates how membranes undergo in vivo hydrolysis and by the 3rd day they become poly(aspartic acid) fibrous membranes, which can be then enzymatically degraded. After one week, the disulfide crosslinked membranes almost completely degrade, while the alkyl-chain crosslinked ones mildly lose their integrity as the surrounding tissue invades them. Histopathology revealed mild acute inflammation, which diminished to a minimal level after seven days.