Rapid, continuous additive manufacturing by volumetric polymerization inhibition patterning.

Contemporary, layer-wise additive manufacturing approaches afford sluggish object fabrication rates and often yield parts with ridged surfaces; in contrast, continuous stereolithographic printing overcomes the layer-wise operation of conventional devices, greatly increasing achievable print speeds and generating objects with smooth surfaces. We demonstrate a novel method for rapid and continuous stereolithographic additive manufacturing by using two-color irradiation of (meth)acrylate resin formulations containing complementary photoinitiator and photoinhibitor species. In this approach, photopatterned polymerization inhibition volumes generated by irradiation at one wavelength spatially confine the region photopolymerized by a second concurrent irradiation wavelength.

Extracellular matrix regulation of fibroblast function: redefining our perspective on skin aging.

The dermal extracellular matrix (ECM) comprises the bulk of skin and confers strength and resiliency. In young skin, fibroblasts produce and adhere to the dermal ECM, which is composed primarily of type I collagen fibrils. Adherence allows fibroblasts to spread and exert mechanical force on the surrounding ECM.

Alopecia and platelet-derived therapies.

Background: Platelet rich plasma (PRP) injections have emerged as a promising regenerative therapy for androgenetic alopecia (AGA). To date, injections of both autologous native and activated PRP have been administered to hair loss patients, and positive results have been observed. However, little to no work has yet to be seen wherein PRP treatments are combined with hair restoration surgeries.

Evaluation of Not-Activated and Activated PRP in Hair Loss Treatment: Role of Growth Factor and Cytokine Concentrations Obtained by Different Collection Systems.

Platelet rich plasma (PRP) was tested as a potential therapy for androgenetic alopecia (AGA) through two different clinical protocols in which one population (18 participants) received half-head treatment with autologous non-activated PRP (A-PRP) produced by CPunT Preparation System (Biomed Device, Modena, Italy) and the other half-head with placebo, and a second separated population in which all participants (n = 6, 3 participants per group) received treatment with calcium-activated PRP (AA-PRP) produced from one of two different PRP collection devices (Regen Blood Cell Therapy or Arthrex Angel System). For the A-PRP study, three treatments were administered over 30-day intervals. Trichoscan analysis of patients, three months post-treatment, showed a clinical improvement in the number of hairs in the target area (36 ± 3 hairs) and in total hair density (65±  5 hair cm2), whereas negligible improvements in hair count (1.

Bactericidal Hydrogels via Surface Functionalization with Cecropin A.

The immobilization of antimicrobial peptides (AMPs) to surfaces, enabling their utilization in biosensor and antibacterial/antifouling coating applications, is typically performed using rigid, solid support materials such as glass or gold and may require lengthy, temperamental protocols. Here, we employ a hydrogel immobilization platform to afford facile fabrication and surface functionalization while offering improved biocompatibility for evaluating the influence of linker length, surface density, and AMP conjugation site on retained peptide activity. Rapid, interfacial photo-polymerization using the radical-mediated thiol-ene addition mechanism was used to generate cross-linked, polymeric coatings bearing residual thiol moieties on prefabricated poly(ethylene glycol) (PEG)-based hydrogel supports.

Thiol-ene functionalized siloxanes for use as elastomeric dental impression materials.

Objectives: Thiol- and allyl-functionalized siloxane oligomers are synthesized and evaluated for use as a radical-mediated, rapid set elastomeric dental impression material. Thiol-ene siloxane formulations are crosslinked using a redox-initiated polymerization scheme, and the mechanical properties of the thiol-ene network are manipulated through the incorporation of varying degrees of plasticizer and kaolin filler. Formulations with medium and light body consistencies are further evaluated for their ability to accurately replicate features on both the gross and microscopic levels.

Redox Initiation of Bulk Thiol-Ene Polymerizations.

The unique formation-structure-property attributes and reaction behavior of the thiol-ene "click" reaction have been explored extensively for photochemically and thermally initiated reactions but have been much less explored for redox initiation. Therefore, the objective of this work is to characterize fully the impact of the initiation system, monomer structure, degree of functionalization, and inhibitor level on the redox-mediated thiol-ene polymerization rate and behavior. Moreover, this study confirms the ability of redox initiation to achieve full conversion of desired thiol-ene "click" products for small molecules in solution.

Synthesis and Characterization of Thiol-Ene Functionalized Siloxanes and Evaluation of their Crosslinked Network Properties.

Three types of linear thiol-functionalized siloxane oligomers and three types of ene-functionalized oligomers were synthesized and subsequently photopolymerized. Within each type of thiol-functionalized oligomer, the ratio of mercaptan repeat units to non-reactive phenyl repeat units was varied to manipulate both the crosslink density and the degree of secondary interactions through pi-pi stacking. Similarly, the repeat units of the three ene-functionalized oligomers are composed of allyl-functional monomers, benzene-functional monomers, and octyl-functional monomers in varying ratios of benzene:octyl but with a constant fraction of allyl moieties.

Comparison of manufacturer-recommended exposure durations with those determined using biaxial flexure strength and scraped composite thickness among a variety of light-curing units.

Statement Of The Problem: Manufacturer-recommended exposure durations for light-curing units are often understated and might not have true clinical relevance.

Purpose: To compare composite depths of cure among exposure durations provided by the manufacturer and those obtained when optimizing exposure duration for biaxial flexural strength or for composite compule-scraping tests when using different light-curing units.

Methods/materials: A hybrid composite (Prodigy, A3, Kerr, Orange, CA, USA) was exposed to different light-curing units (all manufactured by Kerr Demetron) (conventional quartz-tungsten-halogen [QTH], conventional blue light-emitting diode [LED(CONV)] or a high-intensity blue LED light [LED(HIGH)]) for various amounts of time, including that recommended by the manufacturer for the given light.