scholarly journals Significance of Crosslinking Approaches in the Development of Next Generation Hydrogels for Corneal Tissue Engineering

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 319
Author(s):  
Promita Bhattacharjee ◽  
Mark Ahearne
Keyword(s):  
Tissue Engineering ◽  
Chemical Structure ◽  
Biochemical Properties ◽  
Corneal Tissue ◽  
Future Prospects ◽  
Chemical Additives ◽  
Injectable Hydrogels ◽  
Corneal Regeneration ◽  
Key Factor ◽  
Fuchs Endothelial Dystrophy

Medical conditions such as trachoma, keratoconus and Fuchs endothelial dystrophy can damage the cornea, leading to visual deterioration and blindness and necessitating a cornea transplant. Due to the shortage of donor corneas, hydrogels have been investigated as potential corneal replacements. A key factor that influences the physical and biochemical properties of these hydrogels is how they are crosslinked. In this paper, an overview is provided of different crosslinking techniques and crosslinking chemical additives that have been applied to hydrogels for the purposes of corneal tissue engineering, drug delivery or corneal repair. Factors that influence the success of a crosslinker are considered that include material composition, dosage, fabrication method, immunogenicity and toxicity. Different crosslinking techniques that have been used to develop injectable hydrogels for corneal regeneration are summarized. The limitations and future prospects of crosslinking strategies for use in corneal tissue engineering are discussed. It is demonstrated that the choice of crosslinking technique has a significant influence on the biocompatibility, mechanical properties and chemical structure of hydrogels that may be suitable for corneal tissue engineering and regenerative applications.

Corneal epithelium tissue engineering: recent advances in regeneration and replacement of corneal surface

2020 ◽  
Author(s):  
Hamed Nosrati ◽  
Zahra Abpeikar ◽  
Zahra Gholami Mahmoudian ◽  
Mahdi Zafari ◽  
Jafar Majidi ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Corneal Transplantation ◽  
Cell Types ◽  
Biological Properties ◽  
Corneal Tissue ◽  
Corneal Surface ◽  
Infection Transmission ◽  
Tissue Microenvironment ◽  
Corneal Regeneration ◽  
Different Cell Types

Currently, many corneal diseases are treated by corneal transplantation, artificial corneal implantation or, in severe cases, keratoprosthesis. Owing to the shortage of cornea donors and the risks involved with artificial corneal implants, such as infection transmission, researchers continually seek new approaches for corneal regeneration. Corneal tissue engineering is a promising approach that has attracted much attention from researchers and is focused on regenerative strategies using various biomaterials in combination with different cell types. These constructs should have the ability to mimic the native tissue microenvironment and present suitable optical, mechanical and biological properties. In this article, we review studies that have focused on the current clinical techniques for corneal replacement. We also describe tissue-engineering and cell-based approaches for corneal regeneration.

A Brief Introduction to Porphyrin Compounds Used in Tumor Imaging and Therapies

2020 ◽  
Vol 20 ◽  
Author(s):  
Lili Pan ◽  
Yu Ma ◽  
Xiaoai Wu ◽  
Huawei Cai ◽  
Feng Qin ◽  
...  
Keyword(s):  
Tumor Imaging ◽  
Photoacoustic Imaging ◽  
Therapeutic Agents ◽  
Biochemical Properties ◽  
Therapeutic Effects ◽  
Future Prospects ◽  
Animal Tissues ◽  
Sonodynamic Therapy ◽  
Porphyrin Derivatives ◽  
Porphyrin Analogues

Abstract:: As a group of heterocyclic macrocycle organic natural compounds occurring universally in animal tissues and plants, porphyrins are composed of four modified pyrrole subunits. Porphyrin analogues/derivatives possess multiple biochemical properties because of their unique structures and have been extensively investigated in cancer treatment. Studies have shown that porphyrins and their derivatives have the ability to locate in tumor cells in a variety of human cancers, and these compounds not only exhibit potent therapeutic effects as photodynamic agents but also show promising properties in medicinal imaging, such as MRI, photoacoustic imaging, fluorescence imaging and PET/SPECT imaging. This paper reviews the recent reports of porphyrin derivatives as therapeutic agents used in tumor therapies, such as sonodynamic therapy, photodynamic therapy and radiotherapy, as well as imaging agents for multimodality tumor imaging. The limitations of porphyrin-based compounds in tumor treatments and future prospects are also summarized.

Use of Polycaprolactone in Corneal Tissue Engineering: A Review

2021 ◽  
pp. 102402
Author(s):  
Amin Orash Mahmoud Salehi ◽  
Saeed Heidari Keshel ◽  
Farshid Sefat ◽  
Lobat Tayebi
Keyword(s):  
Tissue Engineering ◽  
Corneal Tissue

Characterization of a Novel Collagen Scaffold for Corneal Tissue Engineering

2016 ◽  
Vol 22 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Jie Zhang ◽  
Aran M.G. Sisley ◽  
Alexander J. Anderson ◽  
Andrew J. Taberner ◽  
Charles N.J. McGhee ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Collagen Scaffold ◽  
Corneal Tissue

scholarly journals High-Resolution Bioprinting of Recombinant Human Collagen Type III

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2973
Author(s):  
Rory Gibney ◽  
Jennifer Patterson ◽  
Eleonora Ferraris
Keyword(s):  
Tissue Engineering ◽  
High Resolution ◽  
Collagen Type ◽  
Thin Layers ◽  
Corneal Tissue ◽  
Collagen Type Iii ◽  
Type Iii ◽  
Pure Collagen ◽  
Human Collagen ◽  
Visible Wavelengths

The development of commercial collagen inks for extrusion-based bioprinting has increased the amount of research on pure collagen bioprinting, i.e., collagen inks not mixed with gelatin, alginate, or other more common biomaterial inks. New printing techniques have also improved the resolution achievable with pure collagen bioprinting. However, the resultant collagen constructs still appear too weak to replicate dense collagenous tissues, such as the cornea. This work aims to demonstrate the first reported case of bioprinted recombinant collagen films with suitable optical and mechanical properties for corneal tissue engineering. The printing technology used, aerosol jet® printing (AJP), is a high-resolution printing method normally used to deposit conductive inks for electronic printing. In this work, AJP was employed to deposit recombinant human collagen type III (RHCIII) in overlapping continuous lines of 60 µm to form thin layers. Layers were repeated up to 764 times to result in a construct that was considered a few hundred microns thick when swollen. Samples were subsequently neutralised and crosslinked using EDC:NHS crosslinking. Nanoindentation and absorbance measurements were conducted, and the results show that the AJP-deposited RHCIII samples possess suitable mechanical and optical properties for corneal tissue engineering: an average effective elastic modulus of 506 ± 173 kPa and transparency ≥87% at all visible wavelengths. Circular dichroism showed that there was some loss of helicity of the collagen due to aerosolisation. SDS-PAGE and pepsin digestion were used to show that while some collagen is degraded due to aerosolisation, it remains an inaccessible substrate for pepsin cleavage.

scholarly journals Marine Polysaccharides in Pharmaceutical Applications: Fucoidan and Chitosan as Key Players in the Drug Delivery Match Field

Marine Drugs ◽  
2019 ◽  
Vol 17 (12) ◽  
pp. 654 ◽  
Author(s):  
Ana Isabel Barbosa ◽  
Ana Joyce Coutinho ◽  
Sofia A. Costa Lima ◽  
Salette Reis
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Biomedical Applications ◽  
Chemical Structure ◽  
Final Section ◽  
Biological Properties ◽  
Production Methods ◽  
Bioactive Properties ◽  
Wide Range ◽  
Per Se

The use of marine-origin polysaccharides has increased in recent research because they are abundant, cheap, biocompatible, and biodegradable. These features motivate their application in nanotechnology as drug delivery systems; in tissue engineering, cancer therapy, or wound dressing; in biosensors; and even water treatment. Given the physicochemical and bioactive properties of fucoidan and chitosan, a wide range of nanostructures has been developed with these polysaccharides per se and in combination. This review provides an outline of these marine polysaccharides, including their sources, chemical structure, biological properties, and nanomedicine applications; their combination as nanoparticles with descriptions of the most commonly used production methods; and their physicochemical and biological properties applied to the design of nanoparticles to deliver several classes of compounds. A final section gives a brief overview of some biomedical applications of fucoidan and chitosan for tissue engineering and wound healing.

scholarly journals Truncated Prosequence of Rhizopus oryzae Lipase: Key Factor for Production Improvement and Biocatalyst Stability

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 961 ◽  
Author(s):  
Josu López-Fernández ◽  
Juan J. Barrero ◽  
M. Dolors Benaiges ◽  
Francisco Valero
Keyword(s):  
Amino Acids ◽  
Ionic Strength ◽  
Rhizopus Oryzae ◽  
Lipase Production ◽  
Biochemical Properties ◽  
Mature Sequence ◽  
Rhizopus Oryzae Lipase ◽  
Batch Cultures ◽  
Production Improvement ◽  
Key Factor

Recombinant Rhizopus oryzae lipase (mature sequence, rROL) was modified by adding to its N-terminal 28 additional amino acids from the C-terminal of the prosequence (proROL) to obtain a biocatalyst more suitable for the biodiesel industry. Both enzymes were expressed in Pichia pastoris and compared in terms of production bioprocess parameters, biochemical properties, and stability. Growth kinetics, production, and yields were better for proROL harboring strain than rROL one in batch cultures. When different fed-batch strategies were applied, lipase production and volumetric productivity of proROL-strain were always higher (5.4 and 4.4-fold, respectively) in the best case. rROL and proROL enzymatic activity was dependent on ionic strength and peaked in 200 mM Tris-HCl buffer. The optimum temperature and pH for rROL were influenced by ionic strength, but those for proROL were not. The presence of these amino acids altered lipase substrate specificity and increased proROL stability when different temperature, pH, and methanol/ethanol concentrations were employed. The 28 amino acids were found to be preferably removed by proteases, leading to the transformation of proROL into rROL. Nevertheless, the truncated prosequence enhanced Rhizopus oryzae lipase heterologous production and stability, making it more appropriate as industrial biocatalyst.

scholarly journals Biomimetic vs. Direct Approach to Deposit Hydroxyapatite on the Surface of Low Melting Point Polymers for Tissue Engineering

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2162
Author(s):  
Andri K. Riau ◽  
Subbu S. Venkatraman ◽  
Jodhbir S. Mehta
Keyword(s):  
Tissue Engineering ◽  
Surrounding Tissue ◽  
Processing Temperature ◽  
Corneal Tissue ◽  
Cellular Functions ◽  
Advantages And Disadvantages ◽  
Phase Coating ◽  
Polymeric Substrates ◽  
Immobilization Techniques ◽  
High Processing

Polymers are widely used in many applications in the field of biomedical engineering. Among eclectic selections of polymers, those with low melting temperature (Tm < 200 °C), such as poly(methyl methacrylate), poly(lactic-co-glycolic acid), or polyethylene, are often used in bone, dental, maxillofacial, and corneal tissue engineering as substrates or scaffolds. These polymers, however, are bioinert, have a lack of reactive surface functional groups, and have poor wettability, affecting their ability to promote cellular functions and biointegration with the surrounding tissue. Improving the biointegration can be achieved by depositing hydroxyapatite (HAp) on the polymeric substrates. Conventional thermal spray and vapor phase coating, including the Food and Drug Administration (FDA)-approved plasma spray technique, is not suitable for application on the low Tm polymers due to the high processing temperature, reaching more than 1000 °C. Two non-thermal HAp coating approaches have been described in the literature, namely, the biomimetic deposition and direct nanoparticle immobilization techniques. In the current review, we elaborate on the unique features of each technique, followed by discussing the advantages and disadvantages of each technique to help readers decide on which method is more suitable for their intended applications. Finally, the future perspectives of the non-thermal HAp coating are given in the conclusion.

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