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The use of softeners is essential for enhancing laundered fabrics and hair textures after washing. For these, products based on double‐tailed cationic surfactants are used to reduce friction and static electricity, resulting in softer and smoother fibers. These surfactants form lamellar phases in water, which can be turned into vesicles and other bilayer aggregates upon shearing, greatly impacting on the rheological properties of these formulations. This study aims at elucidating how some parameters of the formulation process impact bilayer structures formation and the product rheology, using di(hydrogenated tallow)dimethylammonium chloride (DHTDMAC) aqueous dispersions as model system. Small angle X‐ray scattering (SAXS) analyses revealed lamellar phases starting from 3% DHTDMAC, with a bilayer thickness of 1.90 ± 0.03 nm, indicating significant carbon chain interdigitation. At this concentration (3%), bilayers exhibited a repetition distance of 69 nm, unveiling a behavior close to the one predicted for infinite swelling, in which lamellar structures persisted even at high dilution. Temperature plays a significant role in the rheological behavior, with elevated temperatures favoring vesicle formation, resulting in reduced apparent viscosity due to lower resistance of vesicles to flow. Upon heating, differential scanning calorimetry (DSC) analyses revealed a transition from Lβ (gel) to Lα (fluid) structures between 28 and 41°C, which was further confirmed by X‐ray diffraction (XRD). Both structural and thermotropic features observed were discussed and compared to information reported for a high‐purity grade homologue of DHTDMAC, dioctadecyldimethylammonium chloride (DODAC) mixed with water. These findings deepen the understanding of fabric softener formulation and the impact of bilayer structures formation on their properties, and should be used to optimize new formulations, enhancing their overall performance and sensorial quality. [ABSTRACT FROM AUTHOR]

Abstract: Neurotechnology as a research area can be defined as the convergence of neuroscience and tissue engineering/regenerative medicine. Through directed global initiatives concentrated on a better understanding of the human brain, an exponential rise in innovative functional biomaterials for the symbiotic integration of man and machine has risen. Unfortunately, neurotechnology as with other disruptive technologies faces the daunting path of traversing the broad chasm between the bench (development of technology) and the bedside (application of technology). Clinical translation of medical devices intended to assess, monitor, and treat sensorimotor injuries must address a selection of design and functional constraints which are cost limiting from a traditional manufacturing perspective. As a highly versatile technology, 3D printing in combination with advanced functional materials can be used to manufacture scaffolds for tissue engineering the neural‐prosthesis interface as well as devices with predesigned capabilities of integrating spatial and temporal data sets usable in a diagnostic and therapeutic context. Therefore, recent neurotechnological advancements will be discussed in the realm of 3D printed functional materials (>2013) with a focus on their potential for clinical translation. [ABSTRACT FROM AUTHOR]

Chronic and acute osteochondral defects as a result of osteoarthritis and trauma present a common and serious clinical problem due to the tissue's inherent complexity and poor regenerative capacity. In addition, cells within the osteochondral tissue are in intimate contact with a 3D nanostructured extracellular matrix composed of numerous bioactive organic and inorganic components. As an emerging manufacturing technique, 3D printing offers great precision and control over the microarchitecture, shape, and composition of tissue scaffolds. Therefore, the objective of this study is to develop a biomimetic 3D printed nanocomposite scaffold with integrated differentiation cues for improved osteochondral tissue regeneration. Through the combination of novel nano-inks composed of organic and inorganic bioactive factors and advanced 3D printing, we have successfully fabricated a series of novel constructs which closely mimic the native 3D extracellular environment with hierarchical nanoroughness, microstructure, and spatiotemporal bioactive cues. Our results illustrate several key characteristics of the 3D printed nanocomposite scaffold to include improved mechanical properties as well as excellent cytocompatibility for enhanced human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and osteochondral differentiation in vitro. The present work further illustrates the effectiveness of the scaffolds developed here as a promising and highly tunable platform for osteochondral tissue regeneration. [ABSTRACT FROM AUTHOR]

Articular cartilage is prone to degeneration and possesses extremely poor self-healing capacity due to inherent low cell density and the absence of a vasculature network. Tissue engineered cartilage scaffolds show promise for cartilage repair. However, there still remains a lack of ideal biomimetic tissue scaffolds which effectively stimulate cartilage regeneration with appropriate functional properties. Therefore, the objective of this study is to develop a novel biomimetic and bioactive electrospun cartilage substitute by integrating cold atmospheric plasma (CAP) treatment with sustained growth factor delivery microspheres. Specifically, CAP was applied to a poly(ε-caprolactone) electrospun scaffold with homogeneously distributed bioactive factors (transforming growth factor-β1 and bovine serum albumin) loaded poly(lactic-co-glycolic) acid microspheres. We have shown that CAP treatment renders electrospun scaffolds more hydrophilic thus facilitating vitronectin adsorption. More importantly, our results demonstrate, for the first time, CAP and microspheres can synergistically enhance stem cell growth as well as improve chondrogenic differentiation of human marrow-derived mesenchymal stem cells (such as increased glycosaminoglycan, type II collagen, and total collagen production). Furthermore, CAP can substantially enhance 3D cell infiltration (over two-fold increase in infiltration depth after 1 day of culture) in the scaffolds. By integrating CAP, sustained bioactive factor loaded microspheres, and electrospinning, we have fabricated a promising bioactive scaffold for cartilage regeneration. [ABSTRACT FROM AUTHOR]

Cartilage tissue is a nanostructured tissue which is notoriously hard to regenerate due to its extremely poor inherent regenerative capacity and complex stratified architecture. Current treatment methods are highly invasive and may have many complications. Thus, the goal of this work is to use nanomaterials and nano/microfabrication methods to create novel biologically inspired tissue engineered cartilage scaffolds to facilitate human bone marrow mesenchymal stem cell (MSC) chondrogenesis. To this end we utilized electrospinning to design and fabricate a series of novel 3D biomimetic nanostructured scaffolds based on hydrogen (H2) treated multi-walled carbon nanotubes (MWCNTs) and biocompatible poly(L-lactic acid) (PLLA) polymers. Specifically, a series of electrospun fibrous PLLA scaffolds with controlled fiber dimension were fabricated in this study. In vitro MSC studies showed that stem cells prefer to attach in the scaffolds with smaller fiber diameter. More importantly, the MWCNT embedded scaffolds showed a drastic increase in mechanical strength and a compressive Young's modulus matching to natural cartilage. Furthermore, our MSC differentiation results demonstrated that incorporation of the H2 treated carbon nanotubes and poly-L-lysine coating can induce more chondrogenic differentiations of MSCs than controls. After two weeks of culture, PLLA scaffolds with H2 treated MWCNTs and poly-L-lysine can achieve the highest glycosaminoglycan synthesis, making them promising for further exploration for cartilage regeneration. [ABSTRACT FROM AUTHOR]

Albumin is the most abundant protein found in healing wounds. Traditional and chromatographic protein isotherms of albumin binding on modified cotton fibers are useful in understanding albumin binding to cellulose wound dressings. An important consideration in the design of cellulosic wound dressings is adsorption and accumulation of proteins like albumin at the solid–liquid interface of the biological fluid and wound dressing fiber. To better understand the effect of fiber charge and molecular modifications in cellulose-containing fibers on the binding of serum albumin as observed in protease sequestrant dressings, albumin binding to modified cotton fibers was compared with traditional and chromatographic isotherms. Modified cotton including carboxymethylated, citrate-crosslinked, dialdehyde and phosphorylated cotton, which sequester elastase and collagenase, were compared for their albumin binding isotherms. Albumin isotherms on citrate-cellulose, cross-linked cotton demonstrated a two-fold increased binding affinity over untreated cotton. A comparison of albumin binding between traditional, solution isotherms and chromatographic isotherms on modified cellulose yielded similar equilibrium constants. Application of the binding affinity of albumin obtained in the in vitro protein isotherm to the in vivo wound dressing uptake of the protein is discussed. The chromatographic approach to assessment of albumin isotherms on modified cellulose offers a more rapid approach to evaluating protein binding on modified cellulose over traditional solution approaches. [ABSTRACT FROM PUBLISHER]

Although the determination of pH is a standard laboratory measurement, new techniques capable of measuring pH are being developed to facilitate modern technological advances. Bio-industrial processing, tissue engineering, and intracellular environments impose unique measurement requirements on probes of pH. We describe a fiber optic-based platform, which measures the heat released by chromophores upon absorption of light. The optical fibers feature fiber Bragg gratings (FBG) whose Bragg peak redshifts with increasing temperature. Using anthocyanins (pH-sensitive chromophores found in many plants), we are able to correlate visible light absorption by a solution of anthocyanins to heat released and changes in FBG signal over a pH range of 2.5–10. We tested the ability of this platform to act as a sensor coating the fiber within a layer of crosslinked polyethylene glycol diacrylate (PEG-DA). Incorporating the anthocyanins into the PEG, we find that the signal magnitude increases over the observed signal at the same pH in solution. Our results indicate that this platform is viable for assessing pH in biological samples and point at ways to optimize performance. [ABSTRACT FROM AUTHOR]

Background: Brachytherapy of thin skin tumors using beta particles can protect underlying sensitive structures such as the bone because of the rapid dose falloff of this type of radiation in tissue. The current work describes a skin brachytherapy applicator, based on beta radiation, that can provide the needed cell‐killing radiation dose matched to the shape of individual skin tumors. Materials and methods: The applicator and its template were fabricated using 3D printing technology. Any clinically approved beta‐emitting isotope in the form of a radioactive gel could theoretically be used in this applicator. Monte Carlo simulations were employed to study the capability of the applicator in conforming dose distribution based on the shape of the tumor. Dose profile in the shallow depth, transverse dose profiles at different depths, and the percent depth dose from this applicator were calculated. The radioisotope of choice for our calculations was Yttrium‐90 (Y‐90). Results: Using the proposed applicator, it is possible to create a desired dose profile matching the tumor surface shape. Conclusion: The short‐range of the beta radiation, together with the dose conforming capability of the applicator, may lead to minimal interactions with the healthy tissue around the skin lesion. [ABSTRACT FROM AUTHOR]

Three-dimensional printing/additive manufacturing (3DP/AM) for tissue engineering and regenerative medicine (TE/RM) applications is a multifaceted research area encompassing biology, material science, engineering, and the clinical sciences. Although being quite mature as a research area, only a handful of clinical cases have been reported and even fewer commercial products have made it to the market. The regulatory pathway and costs associated with the introduction of bioresorbable materials for TE/RM have proven difficult to overcome, but greater access to 3DP/AM has spurred interest in the processing and availability of existing and new bioresorbable materials. For this purpose, herein, we introduce a series of medical-grade filaments for fused deposition modelling/fused filament fabrication (FDM/FFF) based on established and Federal Drug Administration (FDA)-approved polymers. Manufacturability, mechanical characterization, and accelerated degradation studies have been conducted to evaluate the suitability of each material for TE/RM applications. The comparative data serves to introduce these materials, as well as a benchmark to evaluate their potential in hard and soft tissue engineering from a physicochemical perspective. [ABSTRACT FROM AUTHOR]

Abstract Bioelectronic devices enable efficient and effective communication between medical devices and human tissue in order to directly treat patients with various neurological disorders. Due to the mechanical similarity to human tissue, hydrogel-based electronic devices are considered to be promising for biological signal recording and stimulation of living tissues. Here, we report the first three-dimensionally (3D) printable conductive hydrogel that can be photocrosslinked while retaining high electrical conductivity. In addition, we prepared dorsal root ganglion (DRG) cell-encapsulated gelatin methacryloyl (GelMA) hydrogels which were integrated with the 3D printed conductive structure and evaluated for efficiency neural differentiation under electrical stimulation (ES). For enhanced electrical conductivity, a poly(3,4-ethylenedioxythiophene) (PEDOT): polystyrene sulfonate (PSS) aqueous solution was freeze-dried and mixed with polyethylene glycol diacrylate (PEGDA) as the photocurable polymer base. Next, the conductive hydrogel was patterned on the substrate by using a table-top stereolithography (SLA) 3D printer. The fabricated hydrogel was characterized for electrochemical conductivity. After printing with the PEDOT:PSS conductive solution, the patterned hydrogel exhibited decreased printing diameters with increasing of PEDOT:PSS concentration. Also, the resultant conductive hydrogel had significantly increased electrochemical properties with increasing PEDOT:PSS concentration. The 3D printed conductive hydrogel provides excellent structural support to systematically transfer the ES toward encapsulated DRG cells for enhanced neuronal differentiation. The results from this study indicate that the conductive hydrogel can be useful as a 3D printing material for electrical applications. Highlights • 3D printed conductive hydrogel significantly improved the electrical potential for neuronal differentiation. [ABSTRACT FROM AUTHOR]

There is an urgent need in the field of soft tissue engineering (STE) to develop biomaterials exhibiting a high degree of biological and mechanical functionality as well as modularity so that they can be tailored according to patient-specific requirements. Recently, biomimetic soft network composites (SNC) consisting of a water-swollen hydrogel matrix and a reinforcing fibrous network fabricated by melt electrospinning writing technology have demonstrated exceptional mechanical and biological properties, thus becoming strong candidates for STE applications. However, there is a lack of design approaches to tailor and optimize their properties in a non-empirical way. To address this challenge, we propose a numerical model-based approach for the rational design of patient-specific SNC for tissue engineering applications. The approach is rooted in an in silico design library that allows for the selection of biomaterial and architecture combinations for the target application, resulting in reduced time, manpower and costs. To demonstrate the validity of the design strategy, a multiphasic SNC with predefined zone-specific properties that captured the complex zonal mechanical and compositional features of articular cartilage was developed based on the natural design of the native tissue. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Voronoi structure was used to design a patient specific bone scaffold matched to a critical-sized femur defect. • Crucial surgical requirements and manufacturing constraints necessary to facilitate clinical translation of a scaffold design workflow have been accommodated. • Geometrically comparing digitized 3D prints against their designed model is an effective method to assess the fabrication accuracy of scaffolds. • Finite element method models were able to accurately predict the failure locations of the scaffold identified via the compression test. The Voronoi design was utilized for a biodegradable patient-specific bone scaffold with macro pores (>4 mm) for the surgical treatment of a critical-sized bone defect. We have focused on the relationship between scaffold design and mechanical properties. Through a combination of experiments and simulations and have presented morphological and mechanical property maps of scaffold designs based on the Voronoi tessellation. Fused filament fabrication (FFF) was explored as the method of fabrication and prototypes were printed in commercial grade Polylactic Acid (PLA). The subsequent in-silico morphology assessment revealed that the pore sizes ranged from 4.0 to 11.8 mm with a total porosity of 71%. The morphological maps capture the distinct geometry shift between as-designed and as-manufactured scaffolds with an average agreement of 76% where most of the deviations were caused by complications innate to 3D printing. Finite element method models were developed to evaluate mechanical properties and the failure locations of the scaffold were accurately predicted, which was validated by the subsequent quasi-static compression test. This study revealed the potential of the Voronoi tessellation to design patient specific bone scaffolds with macro pore sizes that mimic trabecular bone geometry and concluded that FFF is a suitable method of fabrication for it. [ABSTRACT FROM AUTHOR]