ABSTRACT
There is increasing evidence that cancer progression is linked to tissue viscoelasticity, which challenges the commonly accepted notion that stiffness is the main mechanical hallmark of cancer. However, this new insight has not reached widespread clinical use, as most clinical trials focus on the application of tissue elasticity and stiffness in diagnostic, therapeutic, and surgical planning. Therefore, there is a need to advance the fundamental understanding of the effect of viscoelasticity on cancer progression, to develop novel mechanical biomarkers of clinical significance. Tissue viscoelasticity is largely determined by the extracellular matrix (ECM), which can be simulated in vitro using hydrogel-based platforms. Since the mechanical properties of hydrogels can be easily adjusted by changing parameters such as molecular weight and crosslinking type, they provide a platform to systematically study the relationship between ECM viscoelasticity and cancer progression. This review begins with an overview of cancer viscoelasticity, describing how tumor cells interact with biophysical signals in their environment, how they contribute to tumor viscoelasticity, and how this translates into cancer progression. Next, an overview of clinical trials focused on measuring biomechanical properties of tumors is presented, highlighting the biomechanical properties utilized for cancer diagnosis and monitoring. Finally, this review examines the use of biofabricated tumor models for studying the impact of ECM viscoelasticity on cancer behavior and progression and it explores potential avenues for future research on the production of more sophisticated and biomimetic tumor models, as well as their mechanical evaluation.
ABSTRACT
This work identifies and describes different material-scaffold geometry combinations for cartilage tissue engineering (CTE). Previously reported potentially interesting scaffold geometries were tuned and printed using bioresorbable polycaprolactone and poly(lactide-b-ethylene) block copolymer. Medical grades of both polymers were 3D printed with fused filament fabrication technology within an ISO 7 classified cleanroom. Resulting scaffolds were then optically, mechanically and biologically tested. Results indicated that a few material-scaffold geometry combinations present potential for excellent cell viability as well as for an enhance of the chondrogenic properties of the cells, hence suggesting their suitability for CTE applications.
Subject(s)
Cartilage, Articular , Tissue Engineering , Absorbable Implants , Dioxanes , Ethylene Glycol , Polyesters , Polymers , Printing, Three-Dimensional , Tissue Engineering/methods , Tissue ScaffoldsABSTRACT
Free chlorine is the most commonly used water disinfectant. Measuring its concentration during and after water treatment is crucial to ensure its effectiveness. However, many of the existing methods do not allow for continuous on-line monitoring. Here we demonstrate a solid state chemiresistive sensor using graphene-like carbon (GLC) that overcomes that issue. GLC films that were either bare or non-covalently functionalized with the redox-active phenyl-capped aniline tetramer (PCAT) were successfully employed to quantify aqueous free chlorine, although functionalized devices showed better performance. The response of the sensors to increasing concentrations of free chlorine followed a Langmuir adsorption isotherm in the two tested ranges: 0.01-0.2 ppm and 0.2-1.4 ppm. The limit of detection was estimated to be 1 ppb, permitting the detection of breaches in chlorine filters. The devices respond to decreasing levels of free chlorine without the need for a reset, allowing for the continuous monitoring of fluctuations in the concentration. The maximum sensor response and saturation concentration were found to depend on the thickness of the GLC film. Hence, the sensitivity and dynamic range of the sensors can be tailored to different applications by adjusting the thickness of the films. Tap water samples from a residential area were tested using these sensors, which showed good agreement with standard colorimetric measurement methods. The devices did not suffer from interferences in the presence of ions commonly found in drinking water. Overall, these sensors are a cost-effective option for the continuous automated monitoring of free chlorine in drinking water.
ABSTRACT
Three-dimensional bioprinting combined with natural hydrogels is a promising technology for the treatment of several pathologies and different tissue regeneration. One of the most studied tissues is cartilage, a complex and avascular tissue that displays a limited self-repair capacity after injuries. Herein, the development of alginate-based hydrogels and scaffolds containing different microstructure is presented and the printability of alginate by 3D bioprinting is studied. Rheological characterization was performed for the determination of viscosity and viscoelastic properties of hydrogels and mechanical characterization was carried out for the determination of compressive modulus of alginate hydrogels. All these characteristics were correlated with alginate behaviour during 3D bioprinting process. For the printability evaluation filament diameter, perimeter of the pores, area of the pores and shrinkage of alginate scaffolds were measured. The results demonstrate that alginate microstructure has a great influence on its printability and on hydrogels' physicochemical properties. Molecular weight of alginate determines its viscosity while M/G ratio determines cross-linking conditions and mechanical properties that vary with cross-linking density. These results suggest the importance of an exhaustive control of the viscoelastic and mechanical properties of alginate hydrogels to obtain structures with high resolution and precision.
