A 433-MHz surface acoustic wave sensor with Ni-TiO2-poly(L-lysine) composite film for dopamine determination

Multifunctional Mesoporous Titanium Dioxide Nanodrug for Corneal Haze Treatment and Its Mechanism

Preventing and treating corneal haze is essential after corneal surface refractive surgery. However, the high intraocular pressure that results after applying traditional anti-inflammatory corticosteroids has attracted great attention. Therefore, we synthesized a multifunctional nanomedicine (Tet@TiO2) with controlled drug release, inflammation targeting, and good biocompatibility for corneal haze treatment. In this study, we discovered that Tet@TiO2 and tetrandrine (Tet), but not TiO2, displayed a characteristic absorption peak at 282 nm. Three weeks after transepithelial photorefractive keratectomy surgery, the Tet@TiO2 group displayed significant decreases in nuclear volume, corneal cell edema, type I and III collagen fiber expression, normal organelle morphology, and collagen fiber arrangement. Compared with those in the control and TiO2 groups, the α-smooth muscle actin, connective tissue growth factor, and type III collagen fibers in the Tet@TiO2 group decreased more significantly after fluorometholone eye drop and Tet treatment, indicating that Tet@TiO2 can effectively inhibit the expression of these inflammatory factors during corneal haze formation. Moreover, Tet@TiO2 showed good, sustained antibacterial properties. More importantly, we found that Tet@TiO2 could effectively down-regulate the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and B-cell lymphoma-2 (Bcl-2) and up-regulate the expression of Bcl-2-associated X protein (Bax) by modulating the inflammatory PI3K-AKT-Bax/Bcl-2 signaling pathway after corneal surface refractive surgery to effectively prevent and treat corneal haze by reducing the expression of inflammatory factors.

The Application of Commercial Surface Acoustic Wave Radio Communication Filters as Transducers for DMMP Sensors

In the present study, we used two popular radio communication SAW resonators as a base for gas sensors and tested their performance. Taking into account issues related to sensor sensitivity, the possibility of applying a sensor layer, the availability of devices, and other related issues, we selected two popular single-port resonators with center frequencies of 315 and 433 MHz (models R315 and R433, respectively) for testing purposes. Both resonators were equipped with a sensitive film of hexafluoroisopropanol-substituted polydimethylsiloxane, a material that selectively absorbs molecules with a high ability to form basic hydrogen bonds. Fabricated sensors were used to detect trace amounts of dimethyl methylphosphonate (DMMP) vapor, which has often been used in similar studies as a nerve chemical warfare agent simulant. Sensors using both devices loaded with sensor layers of an optimal thickness rapidly reacted to a gas containing DMMP at a concentration of 3 mg/m3, generating a stable analytical signal ranging from several to several dozen kilohertz. In the case of R433, the frequency signal was 20.5 kHz at 1 min from the beginning of exposure to DMMP. The obtained results showed that the used transducers exhibited good performance as a base for gas sensors. Finally, their suitability for sensing applications was confirmed by a comparison with the results obtained in previous similar studies.

Acoustic Biosensors and Microfluidic Devices in the Decennium: Principles and Applications

Lab-on-a-chip (LOC) technology has gained primary attention in the past decade, where label-free biosensors and microfluidic actuation platforms are integrated to realize such LOC devices. Among the multitude of technologies that enables the successful integration of these two features, the piezoelectric acoustic wave method is best suited for handling biological samples due to biocompatibility, label-free and non-invasive properties. In this review paper, we present a study on the use of acoustic waves generated by piezoelectric materials in the area of label-free biosensors and microfluidic actuation towards the realization of LOC and POC devices. The categorization of acoustic wave technology into the bulk acoustic wave and surface acoustic wave has been considered with the inclusion of biological sample sensing and manipulation applications. This paper presents an approach with a comprehensive study on the fundamental operating principles of acoustic waves in biosensing and microfluidic actuation, acoustic wave modes suitable for sensing and actuation, piezoelectric materials used for acoustic wave generation, fabrication methods, and challenges in the use of acoustic wave modes in biosensing. Recent developments in the past decade, in various sensing potentialities of acoustic waves in a myriad of applications, including sensing of proteins, disease biomarkers, DNA, pathogenic microorganisms, acoustofluidic manipulation, and the sorting of biological samples such as cells, have been given primary focus. An insight into the future perspectives of real-time, label-free, and portable LOC devices utilizing acoustic waves is also presented. The developments in the field of thin-film piezoelectric materials, with the possibility of integrating sensing and actuation on a single platform utilizing the reversible property of smart piezoelectric materials, provide a step forward in the realization of monolithic integrated LOC and POC devices. Finally, the present paper highlights the key benefits and challenges in terms of commercialization, in the field of acoustic wave-based biosensors and actuation platforms.