Development of Monolithic Glass Suspended Microchannel Resonators designed for bead-based bioassays

L'abstract è presente nell'allegato / the abstract is in the attachmen

Detection methodologies for microRNA biomarker profiling

Owing to their pivotal role as expression regulators, microRNAs (miRNAs) have different physiological roles and can be involved in the onset and progression of several diseases. For this reason, their altered presence can be predictive of a pathological state. Furthermore, the ubiquitous presence of these short RNA sequences in basically all body tissues and fluids makes them elite candidates as biomarkers. With this concept in mind, it is fundamental to have effective, sensitive, and selective techniques to perform their accurate detection and profiling. The goal of this chapter is to summarize the pros and cons of some of the available detection approaches used for miRNA profiling, starting from the most common unamplified/amplified probe-based methods to the advanced techniques based on biosensors and bioassays

Advanced ELISA-like Biosensing Based on Ultralarge-Pore Silica Microbeads

In this work, functionalized porous silica-based materials, widely used in the literature as drug and biomolecule nanocarriers, were innovatively used as an effective three-dimensional (3D) substrate for the development of a specific biomolecular assay showing great versatility in terms of detection performance. One-pot synthesis of ultralarge-pore silica microbeads was optimized to develop an enzyme-linked immunosorbent (ELISA)-like DNA detection assay. Cocondensation synthesis enabled introducing thiol functionalities into the silica framework while preserving both the high specific surface area (560 m2/g) and large pore size (17 nm average diameter), which are essential to guaranteeing high loading capability. Indeed, the bead-capturing ability was proved by developing an ELISA-like assay for the detection of short DNA sequences (≈20 bp), both in labeled and label-free configurations. In particular, the suppression of unspecific binding on the bead surface by testing two different blocking agents was a matter of interest. The detection performances were evaluated and compared to the ones obtained by following the same detection protocol on a standard flat surface (two-dimensional, 2D), which is most commonly used for this purpose. The bead-based assay showed a limit of detection two times lower than the flat-surface assay, confirming the promising capturing ability due to the larger active surface area. Furthermore, compared to traditional ELISA, the bead-based assay showed an intrinsic larger dynamic range that can be tailored depending on the final amount of beads used for the colorimetric quantification

Monolithic glass suspended microchannel resonators for enhanced mass sensing of liquids

Suspended microchannel resonators (SMRs) have been recently developed as highly sensitive platforms to study bacteria, cell populations, antibiotic resistance and other micron-sized analytes. Unfortunately, the time-consuming and challenging fabrication process represents the main drawback for the implementation of these platforms as new point-of-care devices. In this work, we show that femtosecond laser direct writing can be successfully implemented as a rapid and cost-effective 3D fabrication process able to define the suspended resonant structure and the embedded microfluidic channel in one-step, only. Furthermore, the use of a fused silica substrate guarantees a totally transparent resonator, a useful property in view of adding optical analyses to the mechanical one. The resonance properties of the fabricated SMRs were accurately characterized in terms of frequency, quality factor and Allan deviation, in different working conditions. The monolithic glass SMR is able to analyze with high precision liquids with different mass density, thanks to a density resolution (1.04·10-3 kg/m3) that is the highest among SMRs and microcapillaries used for this purpose. Finally, the effective biosensing capability is demonstrated by evaluating the microbial load of aqueous solutions containing different concentrations of P. fluorescens

Polymeric 3D Printed Functional Microcantilevers for Biosensing Applications

In this study, we show for the first time the production of mass-sensitive polymeric biosensors by 3D printing technology with intrinsic functionalities. We also demonstrate the feasibility of mass-sensitive biosensors in the form of microcantilever in a one-step printing process, using acrylic acid as functional comonomer for introducing a controlled amount of functional groups that can covalently immobilize the biomolecules onto the polymer. The effectiveness of the application of 3D printed microcantilevers as biosensors is then demonstrated with their implementation in a standard immunoassay protocol. This study shows how 3D microfabrication techniques, material characterization, and biosensor development could be combined to obtain an engineered polymeric microcantilever with intrinsic functionalities. The possibility of tuning the composition of the starting photocurable resin with the addition of functional agents, and consequently controlling the functionalities of the 3D printed devices, paves the way to a new class of mass-sensing microelectromechanical system devices with intrinsic properties