• biomedical devices
• bioresorbable sensor
• in-vivo applications
• layer-by-layer nanoassembly
• porous silicon
• sensor

In this doctoral thesis, a biodegradable chemical sensor is presented for in-vivo pH monitoring. It is created using nanostructured porous silica functionalized through the layer-by-layer technique, employing engineered polymers labelled with fluorophores. The sensor exhibits a significant increase in fluorescent signals, varying in intensity in response to pH fluctuations. The underlying principle relies on fluorescence self-quenching, determined by the increase, and decrease in distance between the fluorophore molecules, depending on the polymer's swelling degree. The pH sensor has been successfully tested in-vivo, demonstrating outstanding performance and ensuring complete biodegradability and biocompatibility in animals.
Using the same technique, a wearable biocompatible sensor has been fabricated: a sensor with a wireless optoelectronic system for real time pH monitoring. The device is capable of wirelessly transmitting pH variation data to an external application, facilitating correlation with potential pathologies.
Lastly, a fully biodegradable and biocompatible implantable sensor has been developed, capable of selectively binding fluorescence drugs and amplifying their fluorescence signal. Specifically, the sensor tracks doxorubicin, a chemotherapeutic antibiotic used to treat various cancers that can be toxic to healthy cells due to its non-selective mechanism of action. Nanostructured porous silicon was utilized for its significant capabilities in chemical and biological detection. The structure was chemically modified to create a doxorubicin-selective sensor, demonstrating excellent performance in in-vitro tests with solutions mimicking bodily fluids and in-vivo tests following intravenous doxorubicin injections in animals.
All presented implantable sensors have proven to be biocompatible and completely biodegradable in in-vivo tests on animals.