An impedimetric study of DNA hybridization on paper-supported inkjet-printed gold electrodes

Disposable biosensors based on metal nanoparticles

The coronavirus disease2019 (COVID-19) pandemic has highlighted the need for disposable biosensors that can detect viruses in infected patients quickly due to fast response and also at a low cost.The present review provides an overview of the applications of disposable biosensors based on metal nanoparticles in enzymatic and non-enzymatic sensors with special reference to glucose and H₂O₂, immunosensors as well as genosensors (DNA biosensors in which the recognized event consists of the hybridization reaction)for point-of-care diagnostics. The disposable biosensors for COVID19 have also been discussed.

Inkjet-Printing of Nanoparticle Gold and Silver Ink on Cyclic Olefin Copolymer for DNA-Sensing Applications

Inkjet technology as a maskless, direct-writing technology offers the potential for structured deposition of functional materials for the realization of electrodes for, e.g., sensing applications. In this work, electrodes were realized by inkjet-printing of commercial nanoparticle gold ink on planar substrates and, for the first time, onto the 2.5D surfaces of a 0.5 mm-deep microfluidic chamber produced in cyclic olefin copolymer (COC). The challenges of a poor wetting behavior and a low process temperature of the COC used were solved by a pretreatment with oxygen plasma and the combination of thermal (130 °C for 1 h) and photonic (955 mJ/cm²) steps for sintering. By performing the photonic curing, the resistance could be reduced by about 50% to 22.7 µΩ cm. The printed gold structures were mechanically stable (optimal cross-cut value) and porous (roughness factors between 8.6 and 24.4 for 3 and 9 inkjet-printed layers, respectively). Thiolated DNA probes were immobilized throughout the porous structure without the necessity of a surface activation step. Hybridization of labeled DNA probes resulted in specific signals comparable to signals on commercial screen-printed electrodes and could be reproduced after regeneration. The process described may facilitate the integration of electrodes in 2.5D lab-on-a-chip systems.

The selection of highly specific and selective aptamers using modified SELEX and their use in process analytical techniques for Lucentis bioproduction

Aptamers for Lucentis were selected using 10 rounds of a modified and highly stringent SELEX process. Affinity column chromatography was used for the binding, partitioning, and elution steps, and the regeneration of ssDNA was performed via asymmetric PCR in the SELEX process. The interaction of aptamers with Lucentis was studied by means of the HADDOCK web server docking program. In addition, the secondary structures of aptamers were interrogated using the mfold web server to check common regions responsible for better affinity towards Lucentis. The two best aptamers for Lucentis (aptamers 1 and 25) were found to have dissociation constant (K_d) values between 23 and 35 nM by means of thermofluorimetric and non-faradaic impedance spectroscopy (NFIS) analysis. The low dissociation constants in the nanomolar range showed the high specificities of the aptamers for Lucentis. Selectivity tests were also performed using both aptamers with different proteins in which negligible responses were obtained from interfering proteins with respect to Lucentis. Although neither of the two aptamers showed prominent responses to the interfering proteins, slightly better selectivity was shown by aptamer 1. The same aptamers were tested for their application in the detection of Lucentis in spiked and real media broth samples. For this detection test, interdigitated (IDT) gold electrodes on a glass substrate were fabricated using standard photolithography and thermal deposition techniques. NFIS measurements were used for the label-free detection of Lucentis in samples. The linear ranges of detection for aptamers 1 and 25 were found to be 22–100 nM and 40–100 nM, respectively. The LODs for aptamers 1 and 25 were calculated to be 22 nM and 40 nM, respectively, which were significantly better than the values from a HPLC-based detection method (about 240 nM). The real sample analysis results were cross-checked via a standard HPLC method, and better correlation was found between the HPLC and aptamer 1 results than the aptamer 25 results; hence, aptamer 1 can be further analyzed and tested for use in affinity column chromatography and detection-kit/chip-based PAT for Lucentis bioproduction.

Highly specific and selective aptamers for Lucentis were selected using 10 rounds of a modified and highly stringent SELEX process.

Low-cost Paper Analytical Devices for Environmental and Biomedical Sensing Applications

Over the last decade, the fabrication of analytical devices utilizing microfluidic structures and lab-on-a-chip platforms has shown breakthrough advancements, both for environmental and biological applications. The ASSURED criteria (affordable, sensitive, specific, user-friendly, robust, equipment-free, delivered), developed by the WHO for diagnostics devices, point towards the need of paper-based analytical devices (PAD) for diagnostics. On the other hand, cost-effective PADs owing the great advantage of affordable applicability in both resource-rich and -limited settings are recently employed for on-site environmental monitoring. In this book chapter, we will discuss about the brief history of paper analytical devices, fabrications, need, and its environmental and biomedical applications.

Tailored Approaches in Drug Development and Diagnostics: From Molecular Design to Biological Model Systems

Approaches to increase the efficiency in developing drugs and diagnostics tools, including new drug delivery and diagnostic technologies, are needed for improved diagnosis and treatment of major diseases and health problems such as cancer, inflammatory diseases, chronic wounds, and antibiotic resistance. Development within several areas of research ranging from computational sciences, material sciences, bioengineering to biomedical sciences and bioimaging is needed to realize innovative drug development and diagnostic (DDD) approaches. Here, an overview of recent progresses within key areas that can provide customizable solutions to improve processes and the approaches taken within DDD is provided. Due to the broadness of the area, unfortunately all relevant aspects such as pharmacokinetics of bioactive molecules and delivery systems cannot be covered. Tailored approaches within (i) bioinformatics and computer-aided drug design, (ii) nanotechnology, (iii) novel materials and technologies for drug delivery and diagnostic systems, and (iv) disease models to predict safety and efficacy of medicines under development are focused on. Current developments and challenges ahead are discussed. The broad scope reflects the multidisciplinary nature of the field of DDD and aims to highlight the convergence of biological, pharmaceutical, and medical disciplines needed to meet the societal challenges of the 21st century.

A Novel Impedimetric Microfluidic Analysis System for Transgenic Protein Cry1Ab Detection

Impedimetric analysis method is an important tool for food safety detection. In this work, a novel impedimetric microfluidic analysis system consisted of a printed gold electrode chip and a microfluidic flow cell was developed for sensitive and selective detection of transgenic protein Cry1Ab. Anti-Cry1Ab aptamer coated magnetic beads were used to recognize transgenic protein Cry1Ab and form Cry1Ab-aptamer modified magnetic beads. After separation, the obtained Cry1Ab-aptamer modified magnetic beads were dissolved in 0.01 M mannitol and followed by injection into the microfluidic flow cell for impedimetric measurement. At the frequency of 358.3 Hz, the impedance signal shows a good linearity with the concentrations of Cry1Ab protein at a range from 0 to 0.2 nM, and the detection limit is 0.015 nM. The results demonstrate that the impedimetric microfluidic analysis system provides an alternative way to enable sensitive, rapid and specific detection of transgenic protein Cry1Ab.

Fabrication of Inkjet-Printed Gold Nanostar Patterns with Photothermal Properties on Paper Substrate

Inkjet printing technology has brought significant advances in patterning various functional materials that can meet important challenges in personalized medical treatments. Indeed, patterning of photothermal active anisotropic gold nanoparticles is particularly promising for the development of low-cost tools for localized photothermal therapy. In the present work, stable inks containing PEGylated gold nanostars (GNSs) were prepared and inkjet printed on a pigment-coated paper substrate. A significant photothermal effect (ΔT ≅ 20 °C) of the printed patterns was observed under near infrared (NIR) excitation of the localized surface plasmon resonance (LSPR) of the GNS with low laser intensity (I ≅ 0.2 W/cm(2)). Besides the pronounced photothermal effect, we also demonstrated, as an additional valuable effect, the release of a model fluorescent thiol-terminated Bodipy dye (BDP-SH) from the printed gold surface, both under bulk heating and NIR irradiation. These preliminary results suggest the way of the development of a new class of low-cost, disposable, and smart devices for localized thermal treatments combined with temperature-triggered drug release.

Low-cost bioanalysis on paper-based and its hybrid microfluidic platforms

Low-cost assays have broad applications ranging from human health diagnostics and food safety inspection to environmental analysis. Hence, low-cost assays are especially attractive for rural areas and developing countries, where financial resources are limited. Recently, paper-based microfluidic devices have emerged as a low-cost platform which greatly accelerates the point of care (POC) analysis in low-resource settings. This paper reviews recent advances of low-cost bioanalysis on paper-based microfluidic platforms, including fully paper-based and paper hybrid microfluidic platforms. In this review paper, we first summarized the fabrication techniques of fully paper-based microfluidic platforms, followed with their applications in human health diagnostics and food safety analysis. Then we highlighted paper hybrid microfluidic platforms and their applications, because hybrid platforms could draw benefits from multiple device substrates. Finally, we discussed the current limitations and perspective trends of paper-based microfluidic platforms for low-cost assays.

On the Slow Diffusion of Point-of-Care Systems in Therapeutic Drug Monitoring

Recent advancements in point-of-care (PoC) technologies show great transformative promises for personalized preventative and predictive medicine. However, fields like therapeutic drug monitoring (TDM), that first allowed for personalized treatment of patients' disease, still lag behind in the widespread application of PoC devices for monitoring of patients. Surprisingly, very few applications in commonly monitored drugs, such as anti-epileptics, are paving the way for a PoC approach to patient therapy monitoring compared to other fields like intensive care cardiac markers monitoring, glycemic controls in diabetes, or bench-top hematological parameters analysis at the local drug store. Such delay in the development of portable fast clinically effective drug monitoring devices is in our opinion due more to an inertial drag on the pervasiveness of these new devices into the clinical field than a lack of technical capability. At the same time, some very promising technologies failed in the clinical practice for inadequate understanding of the outcome parameters necessary for a relevant technological breakthrough that has superior clinical performance. We hope, by over-viewing both TDM practice and its yet unmet needs and latest advancement in micro- and nanotechnology applications to PoC clinical devices, to help bridging the two communities, the one exploiting analytical technologies and the one mastering the most advanced techniques, into translating existing and forthcoming technologies in effective devices.

Inkjet printing of conductive inks with high lateral resolution on omniphobic "R(F) paper" for paper-based electronics and MEMS

The use of omniphobic "fluoroalkylated paper" as a substrate for inkjet printing of aqueous inks that are the precursors of electrically conductive patterns is described. By controlling the surface chemistry of the paper, it is possible to print high resolution, conductive patterns that remain conductive after folding and exposure to common solvents.