Fusing Peptide Epitopes for Advanced Multiplex Serological Testing for SARS-CoV-2 Antibody Detection.

The tragic COVID-19 pandemic, which has seen a total of 655 million cases worldwide and a death toll of over 6.6 million seems finally tailing off. Even so, new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to arise, the severity of which cannot be predicted in advance. This is concerning for the maintenance and stability of public health, since immune evasion and increased transmissibility may arise. Therefore, it is crucial to continue monitoring antibody responses to SARS-CoV-2 in the general population. As a complement to polymerase chain reaction tests, multiplex immunoassays are elegant tools that use individual protein or peptide antigens simultaneously to provide a high level of sensitivity and specificity. To further improve these aspects of SARS-CoV-2 antibody detection, as well as accuracy, we have developed an advanced serological peptide-based multiplex assay using antigen-fused peptide epitopes derived from both the spike and the nucleocapsid proteins. The significance of the epitopes selected for antibody detection has been verified by in silico molecular docking simulations between the peptide epitopes and reported SARS-CoV-2 antibodies. Peptides can be more easily and quickly modified and synthesized than full length proteins and can, therefore, be used in a more cost-effective manner. Three different fusion-epitope peptides (FEPs) were synthesized and tested by enzyme-linked immunosorbent assay (ELISA). A total of 145 blood serum samples were used, compromising 110 COVID-19 serum samples from COVID-19 patients and 35 negative control serum samples taken from COVID-19-free individuals before the outbreak. Interestingly, our data demonstrate that the sensitivity, specificity, and accuracy of the results for the FEP antigens are higher than for single peptide epitopes or mixtures of single peptide epitopes. Our FEP concept can be applied to different multiplex immunoassays testing not only for SARS-CoV-2 but also for various other pathogens. A significantly improved peptide-based serological assay may support the development of commercial point-of-care tests, such as lateral-flow-assays.

Selectively Positioned Catechol Moiety Supports Ultrashort Self-Assembling Peptide Hydrogel Adhesion for Coral Restoration.

Coral reef survival is threatened globally. One way to restore this delicate ecosystem is to enhance coral growth by the controlled propagation of coral fragments. To be sustainable, this technique requires the use of biocompatible underwater adhesives. Hydrogels based on rationally designed ultrashort self-assembling peptides (USP) are of great interest for various biological and environmental applications, due to their biocompatibility and tunable mechanical properties. Implementing superior adhesion properties to the USP hydrogel compounds is crucial in both water and high ionic strength solutions and is relevant in medical and marine environmental applications such as coral regeneration. Some marine animals secrete large quantities of the aminoacids dopa and lysine to enhance their adhesion to wet surfaces. Therefore, the addition of catechol moieties to the USP sequence containing lysine (IIZK) should improve the adhesive properties of USP hydrogels. However, it is challenging to place the catechol moiety (Do) within the USP sequence at an optimal position without compromising the hydrogel self-assembly process and mechanical properties. Here, we demonstrate that, among three USP hydrogels, DoIIZK is the least adhesive and that the adhesiveness of the IIZDoK hydrogel is compromised by its poor mechanical properties. The best adhesion outcome was achieved using the IIZKDo hydrogel, the only one to show equally sound adhesive and mechanical properties. A mechanistic understanding of this outcome is presented here. This property was confirmed by the successful gluing of coral fragments by means of IIZKDo hydrogel that are still thriving after more than three years since the deployment. The validated biocompatibility of this underwater hydrogel glue suggests that it could be advantageously implemented for other applications, such as surgical interventions.

Dipeptide-Based Photoreactive Instant Glue for Environmental and Biomedical Applications.

Nature-inspired smart materials offer numerous advantages over environmental friendliness and efficiency. Emulating the excellent adhesive properties of mussels foot proteins, where the lysine is in close proximity with the 3,4-dihydroxy-l-phenylalanine (DOPA), we report the synthesis of a novel photocurable peptide-based adhesive consisting exclusively of these two amino acids. Our adhesive is a highly concentrated aqueous solution of a monomer, a cross-linker, and a photoinitiator. Lap-shear adhesion measurements on plastic and glass surfaces and comparison with different types of commercial adhesives showed that the adhesive strength of our glue is comparable when applied in air and superior when used underwater. No toxicity of our adhesive was observed when the cytocompatibility on human dermal fibroblast cells was assessed. Preliminary experiments with various tissues and coral fragments showed that our adhesive could be applied to wound healing and coral reef restoration. Given the convenience of the facile synthesis, biocompatibility, ease of application underwater, and high adhesive strength, we expect that our adhesive may find application, but not limited, to the biomedical and environmental field.

Fabrication of a Lateral Flow Assay for Rapid In-Field Detection of COVID-19 Antibodies Using Additive Manufacturing Printing Technologies.

The development of lateral flow immunoassay (LFIA) using three-dimensional (3D) printing and bioprinting technologies can enhance and accelerate the optimization process of the fabrication. Therefore, the main goal of this study is to investigate methods to speed up the developing process of a LFIA as a tool for community screening. To achieve this goal, an in-house developed robotic arm and microfluidic pumps were used to print the proteins during the development of the test. 3D printing technologies were used to design and print the housing unit for the testing strip. The proposed design was made by taking into consideration the environmental impact of this disposable medical device.

Ecologically Friendly Biofunctional Ink for Reconstruction of Rigid Living Systems Under Wet Conditions.

The development of three-dimensional (3D)-printable inks is essential for several applications, from industrial manufacturing to novel applications for biomedical engineering. Remarkably, biomaterials for tissue engineering applications can be expanded to other new horizons; for instance, restoration of rigid living systems as coral reefs is an emergent need derived from recent issues from climate change. The coral reefs have been endangered, which can be observed in the increasing bleaching around the world. Very few studies report eco-friendly inks for matter since most conventional approaches require synthetic polymer, which at some point could be a pollutant depending on the material. Therefore, there is an unmet need for cost-effective formulations from eco-friendly materials for 3D manufacturing to develop carbonate-based inks for coral reef restoration. Our value proposition derives from technologies developed for regenerative medicine, commonly applied for human tissues like bone and cartilage. In our case, we created a novel biomaterial formulation from biopolymers such as gelatin methacrylate, poly (ethylene glycol diacrylate), alginate, and gelatin as scaffold and binder for the calcium carbonate and hydroxyapatite bioceramics needed to mimic the structure of rigid structures. This project presents evidence from 2D/3D manufacturing, chemical, mechanical, and biological characterization, which supports the hypothesis of its utility to aid in the fight to counteract the coral bleaching that affects all the marine ecosystem, primarily when this is supported by solid research in biomaterials science used for living systems, it can extend tissue engineering into new approaches in different domains such as environmental or marine sciences.