Self-Cleaning Bending Sensors Based on Semitransparent ZnO Nanostructured Films

The design of multifunctional nanostructured materials is the key to the development of smart wearable devices. For instance, nanostructures endowed with both piezoelectric and photocatalytic activities could well be the workhorse for solar-light-driven self-cleaning wearable sensors. In this work, a simple strategy for the assembly of a flexible, semitransparent piezophotocatalytic system is demonstrated by leveraging rational wet chemistry synthesis of ZnO-based nanosheets/nanoflowers (NSs/NFs) under basic pH conditions onto flexible ITO/PET supports. A KMnO4 pretreatment before the ZnO synthesis (seeded ZnO) allows for the control of the density, size, and orientation of the NSs/NFs systems compared to the systems produced in the absence of seeding (seedless ZnO). The electrical response of the sensors is extracted at a 1 V bias as a function of bending in the interval between 0 and 90°, being the responsivity toward bending significantly enhanced by the KMnO4 treatment effect. The photocatalytic activity of the sensors is analyzed in aqueous solution (methylene blue, 25 μM) by a solar simulator, resulting in similar values between seedless and seeded ZnO. Upon bending the sensor, the photocatalytic activity of seedless ZnO is almost unaffected, whereas that of seeded ZnO is improved by about 25%. The sensor’s reusability and repeatability are tested in up to three different cycles. These results open up the way toward the seamless integration of bending sensitivity and photocatalysis into a single device

Self-cleaning ZnO/ITO/PET Bending Sensors

The design of multifunctional materials is of pivotal importance for developing wearable biosensors. In particular, the advancement in self-cleaning materials suitable for bending sensors, i.e. devices able to track human body movements for healthcare monitoring [1], has raised much interest in recent pandemic times. Such technology can be facilitated by leveraging piezo-photocatalytic cleaning effects under visible light [2]. Herein, we show a new class of ZnO-based nanosheets (NSs) synthesized in aqueous solution (85 °C, 24 hours) onto seeded or seedless ITO/PET surfaces that couple sensing to photocatalysis. UV-vis and FT-IR spectroscopies show the typical absorption peaks of ZnO. A nano-squared pattern is observed on ITO, likely resulting from mixed SnO2:ZnO nanocubic photocatalytic composites [3]. In the absence of the MnOOH seed layer film (seedless ZnO), NSs show flower-like morphology showing a significantly lower density (about twenty times) with respect to the seeded version. The electrical response of the sensors is extracted at a 1 V bias as a function of bending in the interval between 0° and 90°. The sensing response is dependent on the density of the ZnO NSs. Upon bending from 0° to 90°, the seedless ZnO sensors show 50-70 μA decrease, whereas the seeded ZnO sensors show a 180-200 μA decrease, which is about two times higher than the currently reported ZnO based bending sensors [4]. As a control, the bare ITO supports only show few μA decrease upon bending. The photocatalytic activity of the sensors is analysed in aqueous solution (methylene blue, 25 μM) at 1 Sun illumination. The seeded ZnO sensors show the best photocatalytic performances with respect to seedless ZnO and bare ITO. Upon bending the sensor inside the cuvette, the photocatalytic activities of bare ITO and seeded ZnO are improved (about 30%), whereas seedless ZnO is unaffected. After washing with deionized water, the sensors retain most of their photocatalytic activity. References [1] C. Chiappara, V. Campisciano, G. Arrabito, V. Errico, G. Saggio, G. Buscarino, M. Scopelliti, M. Gruttadauria, F. Giacalone, B. Pignataro, Bending Sensors Based on Thin Films of Semitransparent Bithiophene- Fulleropyrrolidine Bisadducts, ChemPlusChem 2020, 85, 2455. [2] S. C.Tu, Y.X. Guo, Y. H. Zhang, C. Hu, T. R. Zhang, T. Y. Ma, H. W. Huang, Piezocatalysis and Piezo- Photocatalysis: Catalysts Classification and Modification Strategy, Reaction Mechanism, and Practical Application. Adv. Funct. Mater. 2020, 30, 2005158. [3] R. Kumar, Ahmad Umar, Rajesh Kumar, M.S. Chauhan, Yas Al-Hadeethi, ZnO–SnO2 nanocubes for fluorescence sensing and dye degradation applications, Ceramics International, 2021, 47, 6201–6210. [4] M. Panth, B. Cook, M. Alamri, D. Ewing, A. Wilson, and J. Z. Wu, Flexible Zinc Oxide Nanowire Array/Graphene Nanohybrid for High-Sensitivity Strain Detection, ACS Omega 2020 5 (42), 27359-27367

Bone metastases in soft tissue sarcoma patients: a survey of natural history, prognostic value and treatment options

Background: We surveyed the natural history of bone metastases in patients affected by soft tissue sarcoma (STS). Methods: This multicenter retrospective observational study included 135 patients. Histological subtype, characteristics of bone metastases, treatment, skeletal related events (SREs) and disease outcome were recorded. Results: The most represented histological subtypes were leiomyosarcoma (27%) angiosarcoma (13%) and undifferentiated sarcoma (8%). Axial skeleton was the most common site for bone involvement (70%). In 27% of cases, bone metastases were present at the time of diagnosis. Fifty-four (40%) patients developed SREs and the median time to first SRE was 4 months (range 1-9). The most common SRE was the need for radiotherapy (28%) followed by pathological fracture (22%). Median survival after bone progression was 6 months (range 1-14). SREs were associated with decreased overall survival (OS) (P = 0.04). A subgroup analysis revealed that bisphosphonates significantly prolonged median time to first SRE (5 versus 2 months; P = 0.002) while they did not determine an improvement in OS, although a favourable trend was identified (median: 7 versus 5 months; P = 0.105). Conclusions: This study illustrates the burden of bone disease from STS and supports the use of bisphosphonates in this setting

Bone metastases in soft tissue sarcoma: a survey of natural history, prognostic value and treatment options

We surveyed the natural history of bone metastases in patients affected by soft tissue sarcoma (STS)