Cell-laden methacrylated gelatin (GelMA) hydrogels with high (approximately 90%) transparency were prepared to mimic the natural form and function of corneal stroma. They were synthesized from GelMA with a methacrylation degree of 70% as determined by nuclear magnetic resonance. Hydrogels were strong enough to withstand handling. Stability studies showed that 87% of the GelMA hydrogels remained after 21 days in phosphate buffered saline (PBS). Cell viability in the first 2 days was over 90% for the human keratocytes loaded in the gels as determined with the live-dead analysis. Cells in the hydrogel elongated and connected to each other as observed by confocal laser scanning microscopy (CLSM) images and scanning electron microscope analysis after 3 weeks in the culture medium and cells were seen to be distributed throughout the hydrogel bulk. Cells were found to synthesize collagen Types I and V, decorin, and biglycan (representative collagens and proteoglycans of human corneal stroma, respectively) showing that keratocytes maintained their functions and preserved their phenotypes in the hydrogels. Transparency of cell-loaded and cell-free hydrogels after 21 days was found to be over 90% at all time points in the visible light range and was comparable to the transparency of the native cornea. The corneal stroma equivalent produced in this study that has cells entrapped in it leads to a product with homogenous distribution of cells. It was transparent at the very beginning and is expected to allow better vision than nontransparent substrates. It, therefore, has a significant potential to be used as an alternative to the current products used to treat corneal blindness.
The
detection of nucleic acids and their mutation derivatives is
vital for biomedical science and applications. Although many nucleic
acid biosensors have been developed, they often require pretreatment
processes, such as target amplification and tagging probes to nucleic
acids. Moreover, current biosensors typically cannot detect sequence-specific
mutations in the targeted nucleic acids. To address the above problems,
herein, we developed an electrochemical nanobiosensing system using
a phenomenon comprising metal ion intercalation into the targeted
mismatched double-stranded nucleic acids and a homogeneous Au nanoporous
electrode array (Au NPEA) to obtain (i) sensitive detection of viral
RNA without conventional tagging and amplifying processes, (ii) determination
of viral mutation occurrence in a simple detection manner, and (iii)
multiplexed detection of several RNA targets simultaneously. As a
proof-of-concept demonstration, a SARS-CoV-2 viral RNA and its mutation
derivative were used in this study. Our developed nanobiosensor exhibited
highly sensitive detection of SARS-CoV-2 RNA (∼1 fM detection
limit) without tagging and amplifying steps. In addition, a single
point mutation of SARS-CoV-2 RNA was detected in a one-step analysis.
Furthermore, multiplexed detection of several SARS-CoV-2 RNAs was
successfully demonstrated using a single chip with four combinatorial
NPEAs generated by a 3D printing technique. Collectively, our developed
nanobiosensor provides a promising platform technology capable of
detecting various nucleic acids and their mutation derivatives in
highly sensitive, simple, and time-effective manners for point-of-care
biosensing.
Treatment of chronic skin wound such as diabetic ulcers, burns, pressure wounds are challenging problems in the medical area. The aim of this study was to design a bilayer skin equivalent mimicking the natural one to be used as a tissue engineered skin graft for use in the treatments of problematic wounds, and also as a model to be used in research related to skin, such as determination of the efficacy of transdermal bioactive agents on skin cells and treatment of acute skin damages that require immediate response. In this study, the top two layers of the skin were mimicked by producing a multilayer construct combining two different porous polymeric scaffolds: as the dermis layer a sodium carboxymethyl cellulose (NaCMC) hydrogel on which fibroblasts were added, and as the epidermis layer collagen (Coll) or chondroitin sulfate-incorporated collagen (CollCS) on which keratinocytes were added. The bilayer construct was designed to allow cross-talk between the two cell populations in the subsequent layers and achieves paracrine signalling. It had interconnected porosity, high water content, appropriate stability and elastic moduli. Expression of vascular endothelial growth factor (VEGF), basic-fibroblast growth factor (bFGF) and Interleukin 8 (IL-8), and the production of collagen I, collagen III, laminin and transglutaminase supported the attachment and proliferation of cells on both layers of the construct. Attachment and proliferation of fibroblasts on NaCMC were lower compared to performance of keratinocyte on collagen where keratinocytes created a dense and a stratified layer similar to epidermis. The resulting constructs succesfully mimicked in vitro the natural skin tissue. They are promising as grafts for use in the treatment of deep wounds and also as models for the study of the efficacy of bioactive agents on the skin.
Recent research effort in biomaterial development has largely focused on engineering bio-instructive materials to stimulate specific cell signaling. Assessing the biological performance of these materials using time-consuming and trial-and-error traditional...
Three-dimensional
(3D) printing has emerged as a valuable tool
in medicine over the past few decades. With a growing number of applications
using this advanced processing technique, new polymer libraries with
varied properties are required. Herein, we investigate tyrosol-based
poly(ester-arylate)s as biodegradable inks in fused deposition modeling
(FDM). Tyrosol-based polycarbonates and polyesters have proven to
be useful biomaterials due to their excellent tunability, nonacidic
degradation components, and the ability to be functionalized. Polymers
are synthesized by polycondensation between a custom diphenol and
commercially available diacids. Thermal properties, degradation rates,
and mechanical properties are all tunable based on the diphenol and
diacid chosen. Evaluation of material print as it relates to chemical
structure, molecular weight, and thermal properties was explored.
Higher-molecular-weight polymers greater than 50 kDa exhibit thermal
degradation during printing and at some points are too viscous to
print. It was determined that polymers with lower processing temperatures
and molecular weights were printable regardless of the structure.
An exception to this was pHTy6 that was printed at 65 kDa with minimal
degradation. This is most likely due to its low melting temperature
and, as a result, lower printing temperatures. Additionally, chemical
improvements were made to incorporate thiol–alkene click chemistry
as a means for postprint curing. Low-molecular-weight pHTy6 was end-capped
with alkene functionality. This material was then formulated with
either a dithiol for chain extension or tetrathiol for cross-linking.
Scaffolds were cured after printing for 5, 15, 30 and 60 min intervals
where longer cure times resulted in a tougher material. This design
builds on the library of biologically active materials previously
explored and aims to bring new biomaterials to the field of 3D-printed
personal medicine.
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