The pandemic showed how early screening and precise monitoring of the individual state of health is a must to avoid serious outbreaks, with all the consequences for the public health and the ...international society itself. Observing also parallel application external to viral or bacterial agents, pre-screening for neoplasms has proven time and time again to lesser the costs of treatment, with higher chances of survival for the patients involved. Nonetheless, the development of reliable, fast responding medical devices is not always easily carried out, given the various nature of the diseases and markers observed. Nanostructured chemoresistive sensors have proven time and time again their capability to detect small quantities (up to part per billions) of the most various and exotic mixtures of volatile organic compounds, for the widest variety of applications, and in particular in medical-screening fields, for both mundane and oncological pathologies, since the last two decades. In this work, a review on the topic, researching on multiple pathologies and microorganism (and their correlated markers) was conducted. The experimental results on the various volatile organic compounds of medical interest were analyzed, given from foreign works and the sensors developed from the team, targeting both pure biomarkers from gas tubes and various emanations from biological samples of human origins, like blood and tissue from surgeries. It was finally observed how different chemoresistive sensors have the capacity to proper distinguish healthy and diseased/tumor affected patients, even with concentration of the markers resembling early stages of the pathologies.
Despite the great progress in screening techniques and medical treatments, colorectal cancer remains one of the most widespread cancers in both sexes, with a high death rate. In this work, the ...volatile compounds released from human colon cancer tissues were detected by a set of four different chemoresistive sensors, made with a nanostructured powder of metal-oxide materials, inserted into an innovative patented device. The sensor responses to the exhalation of a primary cancer sample and of a healthy sample (both of the same weight, collected during colorectal surgery from the intestine of the same patient) were statistically analyzed. The sensors gave reversible, reproducible, and fast responses for at least one year of continuous use, making them quite superior in respect to the existing diagnostic methods. Preliminary results obtained using principal component analysis of the sensor responses to samples removed from 13 patients indicate that the nanostructured sensors employed in this study were able to distinguish between healthy and tumor tissue samples with coherent responses (the discrimination power of the most sensitive sensor was about 17%), highlighting a strong potential for clinical practice.
Among the various chemoresistive gas sensing properties studied so far, the sensing response reproducibility, i.e., the capability to reproduce a device with the same sensing performance, has been ...poorly investigated. However, the reproducibility of the gas sensing performance is of fundamental importance for the employment of these devices in on-field applications, and to demonstrate the reliability of the process development. This sensor property became crucial for the preparation of medical diagnostic tools, in which the use of specific chemoresistive gas sensors along with a dedicated algorithm can be used for screening diseases. In this work, the reproducibility of SmFeO3 perovskite-based gas sensors has been investigated. A set of four SmFeO3 devices, obtained from the same screen-printing deposition, have been tested in laboratory with both controlled concentrations of CO and biological fecal samples. The fecal samples tested were employed in the clinical validation protocol of a prototype for non-invasive colorectal cancer prescreening. Sensors showed a high reproducibility degree, with an error lower than 2% of the response value for the test with CO and lower than 6% for fecal samples. Finally, the reproducibility of the SmFeO3 sensor response and recovery times for fecal samples was also evaluated.
Preventive screening does not only allow to preemptively intervene on pathologies before they can harm the host; but also to reduce the costs of the intervention itself; boosting the efficiency of ...the NHS (National Health System) by saving resources for other purposes. To improve technology advancements in this field; user-friendly yet low-cost devices are required; and various applications for gas sensors have been tested and proved reliable in past studies. In this work; cell cultures and blood samples have been studied; using nanostructured chemoresistive sensors; to both verify if this technology can reliably detect tumor markers; and if correlations between responses from tumor line metabolites and the screening outcomes on human specimens could be observed. The results showed how sensors responded differently to the emanations from healthy and mutant (for cells) or tumor affected (for blood) samples, and how those results were consistent between them, since the tumoral specimens had higher responses compared to the ones of their healthy counterparts. Even though the patterns in the responses require a bigger population to be defined properly; it appeared that the different macro-groups between the same kind of samples are distinguishable from some of the sensors chosen in the study; giving promising outcomes for further research.
Numerous medical studies show that tumor growth is accompanied by protein changes that may lead to the peroxidation of the cell membrane with consequent emission of volatile organic compounds (VOCs) ...by breath or intestinal gases that should be seen as biomarkers for colorectal cancer (CRC). The analysis of VOCs represents a non-invasive and potentially inexpensive preliminary screening technique. An array of chemoresistive gas sensors based on screen-printed metal oxide semiconducting films has been selected to discriminate gases of oncological interest, e.g., 1-iodononane and benzene, widely assumed to be biomarkers of colorectal cancer, from those of interference in the gut, such as methane and nitric oxide.
Colorectal and gastric malignant neoplasms (1) produce tumor markers of various nature (a) that, being vascularized, pollute the blood stream (2). These markers are detected with a device (3) hosting ...nanostructured chemoresistive sensors (4), by sampling blood specimens from human donors and putting them into the device specimen chamber. A filtered airflow brings the markers released to the sensitive chambers, where sensors reacts to their presence. Sensor responses are then analyzed via statistical methods (i.e. Principal Component Analysis), allowing to identify, in this work, if the specimen is sampled from a healthy or tumor affected donor.
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•A device encasing chemoresistive sensors was used to monitor tumor markers.•Different tumor markers are emanated from the blood samples, forming odor patterns.•Single sensor approach showed promising yet modest results with ST25 650 + Au sensor.•PCA approach showed good discrimination between “healthy” and “tumor” populations.
Nowadays, the demand for devices capable of efficiently identifying the presence of various biomarkers in human body, connected to a wide variety of pathologies, is progressively increasing. Chemoresistive semiconductor sensors, capable of changing their conductance depending on the chemical reactions between their surface and gaseous analytes, could be a suitable choice for medical devices implementation. In this work, a prototype based on an array of nanostructured sensors was tested, in order to detect the presence of airborne tumor markers in blood samples. These chemicals were conveyed to sensors with an air-flow circuit, equipped with antibacterial filters to maintain the sterility of the system. Resulting signals were acquired, processed and plotted thanks to a custom-made software, realized in Labview®. Statistics on these signals was performed by means of Principal Component Analysis. Both male and female subjects, ranging between 21 to 91 years of age, have accepted to participate in this study, donating their blood samples. Donors were patients affected by colorectal and stomach cancers, at different stages of evolution, and/or having differently localized metastasis, and a healthy control group. The results have shown that the processed sensor responses, well discriminate healthy and tumor affected subjects. Obtained results can be also employed to assess the level of tumor growth and vascularization.
The detection of volatile organic compounds (VOCs) exhaled by human body fluids is a recent and promising method to reveal tumor formations. In this feasibility study, a patented device, based on ...nanostructured chemoresistive gas sensors, was employed to explore the gaseous exhalations of tumoral, immortalized, and healthy cell lines, with the aim of distinguishing their VOC patterns. The analysis of the device output to the cell VOCs, emanated at different incubation times and initial plating concentrations, was performed to evaluate the device suitability to identify the cell types and to monitor their growth. The sensors ST25 (based on tin and titanium oxides), STN (based on tin, titanium, and niobium oxides), and TiTaV (based on titanium, tantalum and vanadium oxides) used here, gave progressively increasing responses upon the cell density increase and incubation time; the sensor W11 (based on tungsten oxide) gave instead unreliable responses to all cell lines. All sensors (except for W11) gave large and consistent responses to RKO and HEK293 cells, while they were less responsive to CHO, A549, and CACO-2 ones. The encouraging results presented here, although preliminary, foresee the development of sensor arrays capable of identifying tumor presence and its type.
Among the various chemoresistive gas sensing properties studied so far, the sensing response reproducibility, i.e., the capability to reproduce a device with the same sensing performance, has been ...poorly investigated. However, the reproducibility of the gas sensing performance is of fundamental importance for the employment of these devices in on-field applications, and to demonstrate the reliability of the process development. This sensor property became crucial for the preparation of medical diagnostic tools, in which the use of specific chemoresistive gas sensors along with a dedicated algorithm can be used for screening diseases. In this work, the reproducibility of SmFeO
perovskite-based gas sensors has been investigated. A set of four SmFeO
devices, obtained from the same screen-printing deposition, have been tested in laboratory with both controlled concentrations of CO and biological fecal samples. The fecal samples tested were employed in the clinical validation protocol of a prototype for non-invasive colorectal cancer prescreening. Sensors showed a high reproducibility degree, with an error lower than 2% of the response value for the test with CO and lower than 6% for fecal samples. Finally, the reproducibility of the SmFeO
sensor response and recovery times for fecal samples was also evaluated.
One of the greatest goals in medicine is early-stage detection of tumors, to allow physicians and surgeons to apply the available therapies, which are usually successful on small volume cancers only. ......
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