Rapid and simple single-chamber nucleic acid detection system prepared through nature-inspired surface engineering

Background: Nucleic acid (NA)-based diagnostics enable a rapid response to various diseases, but current techniques often require multiple labor-intensive steps, which is a major obstacle to successful translation to a clinical setting. Methods: We report on a surface-engineered single-chamber device for NA extraction and in situ amplification without sample transfer. Our system has two reaction sites: A NA extraction chamber whose surface is patterned with micropillars and a reaction chamber filled with reagents for in situ polymerase-based NA amplification. These two sites are integrated in a single microfluidic device; we applied plastic injection molding for cost-effective, mass-production of the designed device. The micropillars were chemically activated via a nature-inspired silica coating to possess a specific affinity to NA. Results: As a proof-of-concept, a colorimetric pH indicator was coupled to the on-chip analysis of NA for the rapid and convenient detection of pathogens. The NA enrichment efficiency was dependent on the lysate incubation time, as diffusion controls the NA contact with the engineered surface. We could detect down to 1×103 CFU by the naked eye within one hour of the total assay time. Conclusion: We anticipate that the surface engineering technique for NA enrichment could be easily integrated as a part of various types of microfluidic chips for rapid and convenient nucleic acid-based diagnostics. © 2021 Ivyspring International Publisher. All rights reserved.1

Gold Nanoparticle-Enhanced and Roll-to-Roll Nanoimprinted LSPR Platform for Detecting Interleukin-10

Localized surface plasmon resonance (LSPR) is a powerful platform for detecting biomolecules including proteins, nucleotides, and vesicles. Here, we report a colloidal gold (Au) nanoparticle-based assay that enhances the LSPR signal of nanoimprinted Au strips. The binding of the colloidal Au nanoparticle on the Au strip causes a red-shift of the LSPR extinction peak, enabling the detection of interleukin-10 (IL-10) cytokine. For LSPR sensor fabrication, we employed a roll-to-roll nanoimprinting process to create nanograting structures on polyethylene terephthalate (PET) film. By the angled deposition of Au on the PET film, we demonstrated a double-bent Au structure with a strong LSPR extinction peak at ~760 nm. Using the Au LSPR sensor, we developed an enzyme-linked immunosorbent assay (ELISA) protocol by forming a sandwich structure of IL-10 capture antibody/IL-10/IL-10 detection antibody. To enhance the LSPR signal, we introduced colloidal Au nanocube (AuNC) to be cross-linked with IL-10 detection antibody for immunogold assay. Using IL-10 as a model protein, we successfully achieved nanomolar sensitivity. We confirmed that the shift of the extinction peak was improved by 450% due to plasmon coupling between AuNC and Au strip. We expect that the AuNC-assisted LSPR sensor platform can be utilized as a diagnostic tool by providing convenient and fast detection of the LSPR signal. © Copyright © 2020 Baek, Song, Lee, Kim, Kim, Wi, Ok, Park, Hong, Kwak, Lee and Nam.1

G-SNAP: A gelation-based single-step naked-eye assay platform mediated by biomarker-triggered enzymatic quinone tanning

Here, we report a novel strategy for rapid and convenient biomarker detection through the naked eye by temporally controlling nature-inspired quinone tanning in a biomarker-specific manner. Quinone tanning is one of the smartest strategies for crosslinking biopolymers chosen by living organisms because of its high efficiency under ambient conditions, arising from the low redox potential of catechol moieties and the high reactivity of the quinone states. However, this efficient mechanism ironically makes it difficult to control the reaction temporally under the desired conditions. Herein, we suggest a dual-enzyme system triggered by biomarker metabolism that can temporally switch on quinone tanning, resulting in rapid sol-gel transition of catechol-conjugated biopolymers. Gelation is a visible indication of the presence of biomarkers, even when dissolved in colored media such as blood and urine. As a demonstration, we established a gelation-based single-step naked-eye assay platform (G-SNAP) for rapid and convenient glucose sensing. The optimized system could detect up to 7 mM glucose in human serum within 1 h by a simple capillary test visualized with the naked eye. The dual enzyme cascade G-SNAP, one for biomarker recognition and the other for quinone tanning, not only allows for signal amplification due to a high turnover rate but also ensures high intrinsic specificity for biomarkers without interference even in complex bio-fluids. © 2022 Elsevier B.V.FALS

Nature‐Inspired Adhesive Catecholamines for Highly Concentrated Colorimetric Signal in Spatial Biomarker Labeling

Colorants have been utilized for precise biomarker detection in rapid and convenient colorimetric bioassays. However, the diffusion of colorants in solution often results in poor sensitivity, which is a major obstacle to the clinical translation of current colorants. To address this issue, in the current study, a unique colorant is developed that possesses adhesiveness for concentration near the target biomarker, avoiding diffusion. In nature, the synergistic interplay between catechol and amine functional groups is thought to be key for the unique mechanism of marine mussel adhesion. In addition, polymerized catecholamines are found in nature as biopigments, that is, in melanin. The dual role of catechol/catecholamine moieties in natural organics inspire to design novel colorimetric bioassays based on an adhesive colorant. Horseradish peroxidase (HRP) is used to initiate in situ polymerization of the catecholic precursors with amine-containing additive molecules and simultaneously attach them near the HRP-labeled biomarkers. This novel catecholamine-based adhesive colorant provides an excellent quantitative (naked-eye) visible signal and it also generates superb spatial information on the biomarkers on complex surfaces (e.g., cell membranes). © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimFALS

Controlling mechanical properties of bio-inspired hydrogels by modulating nano-scale, inter-polymeric junctions

Quinone tanning is a well-characterized biochemical process found in invertebrates, which produce diverse materials from extremely hard tissues to soft water-resistant adhesives. Herein, we report new types of catecholamine PEG derivatives, PEG-NH-catechols that can utilize an expanded spectrum of catecholamine chemistry. The PEGs enable simultaneous participation of amine and catechol in quinone tanning crosslinking. The intermolecular reaction between PEG-NH-catechols forms a dramatic nano-scale junction resulting in enhancement of gelation kinetics and mechanical properties of PEG hydrogels compared to results obtained by using PEGs in the absence of amine groups. Therefore, the study provides new insight into designing new crosslinking chemistry for controlling nano-scale chemical reactions that can broaden unique properties of bulk hydrogels

Dialysis-derived urchin-like supramolecular assembly of tannic acid and paclitaxel with high porosity

Co-crystallization of active pharmaceutical ingredients (APIs) with pharmaceutically acceptable additives has emerged as an alternative to current drug delivery systems for hydrophobic drugs, due to their high drug loading efficiency. During this process, we herein report that tannic acid (TA) can be used as an amphiphilic stabilizer for the model drug, paclitaxel (PTX), that results in the shape and morphology variations of the synthesized microstructures, depending on the synthetic environment. We observed that rapid co-precipitation of PTX and TA via dialysis in water resulted in unprecedented urchin-like supramolecular microstructures with high porosity. On the other hand, slow co-precipitation for several hours under static conditions without dialysis exhibited bundles of straight TA-coated PTX fibers without any pores. This was plausibly due to the dynamic change of both the building block concentration and the solvent composition occurring during the transition of the kinetic product to the thermodynamic product. Interestingly, the synthesized urchin-like porous structure further rapidly transformed into a spherical shape through the interaction with serum proteins by remodeling of the non-covalent interactions, which contributed to the overall therapeutic efficacy tested in vitro. Our results provide knowledge on the self-assembly behavior of the hydrophobic drug and amphiphilic stabilizer under dynamic conditions, and contribute to the development of novel strategies in designing drug formulations. This journal is © The Royal Society of Chemistry.1

Recent advances in melanin-like nanomaterials in biomedical applications: a mini review

Background: Melanins are a group of biopigments in microorganisms that generate a wide range of colorants. Due to their multifunctionality, including ultraviolet protection, radical scavenging, and photothermal conversion, in addition to their intrinsic biocompatibility, natural melanins and synthetic melanin-like nanomaterials have been suggested as novel nano-bio platforms in biomedical applications. Main body: Recent approaches in the synthesis of melanin-like nanomaterials and their biomedical applications have briefly been reviewed. Melanin-like nanomaterials have been suggested as endogenous chromophores for photoacoustic imaging and radical scavengers for the treatment of inflammatory diseases. The photothermal conversion ability of these materials under near-infrared irradiation allows hyperthermia-mediated cancer treatments, and their intrinsic fluorescence can be an indicator in biosensing applications. Furthermore, catechol-rich melanin and melanin-like nanomaterials possess a versatile affinity for various functional organic and inorganic additives, allowing the design of multifunctional hybrid nanomaterials that expand their range of applications in bioimaging, therapy, theranostics, and biosensing. Conclusion: Melanin-like natural and synthetic nanomaterials have emerged; however, the under-elucidated chemical structures of these materials are still a major obstacle to the construction of novel nanomaterials through bottom-up approaches and tuning the material properties at the molecular level. Further advancements in melanin-based medical applications can be achieved with the incorporation of next-generation chemical and molecular analytical tools. © 2019 The Author(s).TRU

A nature-inspired protective coating on soft/wet biomaterials for SEM by aerobic oxidation of polyphenols

Phenolamine networks are one of the major structural components in the insect exoskeletons called cuticles. An insect cuticle-inspired surface protective coating named "aerobic oxidation of polyphenol leading to artificial exoskeleton", APPLE, is reported. The coating layer can be formed on any solid surface, because the oxygen in the air triggers the formation of the APPLE coating. The oxidized pyrogallol, called pyrogallol-quinone, is rapidly reacted with polyamine to form mechanically robust organic thin film networks. As some insect cuticles can be directly imaged under extreme conditions, such as in the vacuum chamber of a scanning electron microscope (SEM) without conventional metal deposition, the surface morphology of APPLE-coated materials (particularly soft ones) can also be imaged by SEM without conventional metal deposition. The APPLE coating is a pure organic flexible layer which is formed within a couple of minutes. Another advantage of the APPLE layer is the suppression of the vapor gas emission from the soft materials, allowing SEM imaging of wet samples such as hydrogels and living tissues. Considering that the traditional studies of phenolic molecules focus mostly on surface functionalization, our study opens a new research direction in which such phenolic coatings might be useful for applications in extreme conditions.TRU

Material-Selective Polydopamine Coating in Dimethyl Sulfoxide

Polydopamine coating is known to be performed in a material-independent manner and has become a popular tool when designing a surface-functionalization strategy of a given material. Studies to improve polydopamine coatings have been reported, aiming to reduce the coating time (by transition metals, oxidants, applied voltages, or microwave irradiation), control surface roughness using catechol derivatives, and vary the ad-layer molecules formed on an underlying polydopamine layer. However, none of the techniques have changed the most important intrinsic property of polydopamine, the surface-independent coating. Currently, no method has been reported to modify this property to create a material-selective 'smart' polydopamine coating. Herein, we report a method with polydopamine to differentiate the chemistry of surfaces. We found that the polydopamine coating was largely inhibited on silicon-containing surfaces such as Si wafers and quartz crystals in a dimethyl sulfoxide (DMSO)/phosphatebuffered saline (PBS) cosolvent, while the coating properties on other materials remained mostly unchanged. Among the various interface bonding mechanisms of coordination, namely, cation-π, π-π stacking, and hydrogen-bonding interactions, the DMSO/PBS cosolvent effectively inhibits hydrogen-bond formation between catechol and SiO2, resulting in surface-selective 'smart' polydopamine coatings. The new polydopamine coating is useful for functionalizing patterned surfaces such as Au patterns on SiO2 substrates. Considering that Si wafer is the most widely used substrate, the surface-selective polydopamine coating technique described herein opens up a new direction in surface functionalization and interface chemistry. © 2020 American Chemical Society.FALS