Polyphenols are important compounds of the plant secondary metabolism, being involved in the plant response to abiotic and biotic stresses and conferring quality properties to fruits and vegetables. Their determination provides valuable information to be used in precision agriculture and in plant physiology studies. Non-destructive evaluation of polyphenols, present in leaf epidermises and fruit skins, can be determined indirectly by multispectral measurements of the chlorophyll fluorescence from the underlying cell layers. This technique, called the chlorophyll fluorescence excitation screening (ChlFES) method, is based on the spectral attenuation by superficial compounds of the incoming radiation impinging on chlorophyll molecules. Examples of the non-destructive monitoring of plant flavonoids response to different UV radiation regimes are reported. Application of the ChlFES to apples, olives, kiwifruits, plums and mainly wine grape to detect flavonoids and anthocyanins was aimed to select fruits with the highest nutraceutical value. In field appliance of the technique by portable fluorescence sensors allowed the control of the wine grape phenolic maturity during the season and the mapping of the grape phenolic content in the vineyard to perform selective harvest and then the production of top-quality wines. Furthermore, the estimate of the plant nutrient status as proximal sensing of the leaf nitrogen content was proved on different crops and proposed to drive precision fertilization.
Plasmonic particles like gold nanorods have aroused interest as contrast agents and labels for applications in biomedical optics and photonic sensing.
Here, we review our recent work on complementary use cases of gold nanorods: A concept of cellular vehiculation with tumor-tropic cells, such as immune system cells or stem cells for efficient delivery to the tumor microenvironment; Ways to improve the biosensors of the types in use to detect COVID-19, and in particular, to make the so-called molecular tests much faster with plasmonic PCR (Polymerase Chain Reaction), and the rapid antigen tests much more sensitive by multiplexing and machine learning.
Laser-generated fenestration is an alternative option for the intraoperative and selective modification of a endovascular endograft, especially in cases where patients are unsuitable for a standard endovascular aneurysms repair. Recently, diode laser approach has been proposed as a substitution of mechanical fenestration. In fact, using a near infrared wavelength (810 nm), the stent graft fabric can be successfully perforated. In this work we report an ex-vivo study providing the harmlessness of laser irradiation effects on biological tissue surrounding the endograft wall. 225 samples of human aortic tissue were irradiated varying energy and pulse duration of an 810 nm diode laser. Irradiated tissues were analyzed under histological examination. Thermal damage was evidenced in the 7.5% of the irradiated samples, typically in the contact area between the laser fiber tip and the aortic wall. These experiments suggest that the diode laser can be safely used for the proposed surgical application.
The increasing interest around imaging and microsurgery techniques based on the photoacoustic effect has boosted active research into the development of exogenous contrast agents that may enhance the potential of this innovative approach.
In this context, plasmonic particles as gold nanorods are achieving resounding interest, owing to their efficiency of photothermal conversion, intense optical absorbance in the near infrared region, inertness in the body and convenience for conjugation with ligands of molecular targets.
On the other hand, the photoinstability of plasmonic particles remains a remarkable obstacle. In particular, gold nanorods easily reshape into nanospheres and so lose their optical absorbance in the near infrared region, under exposure to few-ns-long laser pulses. This issue is attracting much attention and stimulating ad-hoc solutions, such as the addition of rigid shells and the optimization of multiple parameters.
In this contribution, we focus on the influence of the shape of gold nanorods on their photothermal behavior and photostability. We describe the photothermal process in the gold nanorods by modeling their optical absorption and consequent temperature dynamics as a function of their aspect ratio (length / diameter).
Our results suggest that increasing the aspect ratio does probably not limit the photostability of gold nanorods, while shifting the plasmonic peak towards wavelengths around 1100 nm, which hold more technological interest.
Photoacoustic imaging and microsurgery have recently attracted attention for applications in oncology. Here, we present a versatile set-up to trigger vapor microbubbles around plasmonic nanoparticles by a combined light-ultrasound excitation. This system enables the detection and parametrization of bubbles as a function of several variables, such us optical fluence, ultrasound intensity, nanoparticles concentration, thus providing useful directions to the development of new strategies for treatments based on optical cavitation.
Robotic surgery is a reality in several surgical fields, such as in gastrointestinal surgery. In ophthalmic surgery the required high spatial precision is limiting the application of robotic system, and even if several attempts have been designed in the last 10 years, only some application in retinal surgery were tested in animal models. The combination of photonics and robotics can really open new frontiers in minimally invasive surgery, improving the precision, reducing tremor, amplifying scale of motion, and automating the procedure. In this manuscript we present the preliminary results in developing a vision guided robotic platform for laser-assisted anterior eye surgery. The robotic console is composed by a robotic arm equipped with an "end effector" designed to deliver laser light to the anterior corneal surface. The main intended application is for laser welding of corneal tissue in laser assisted penetrating keratoplasty and endothelial keratoplasty. The console is equipped with an integrated vision system. The experiment originates from a clear medical demand in order to improve the efficacy of different surgical procedures: when the prototype will be optimized, other surgical areas will be included in its application, such as neurosurgery, urology and spinal surgery.
Robotic surgery is a reality in several surgical fields, such as in gastrointestinal surgery. In ophthalmic surgery the required high spatial precision is limiting the application of robotic system, and even if several attempts have been designed in the last 10 years, only some application in retinal surgery were tested in animal models. The combination of photonics and robotics can really open new frontiers in minimally invasive surgery, improving the precision, reducing tremor, amplifying scale of motion, and automating the procedure. In this manuscript we present the preliminary results in developing a vision guided robotic platform for laser-assisted anterior eye surgery. The robotic console is composed by a robotic arm equipped with an "end effector" designed to deliver laser light to the anterior corneal surface. The main intended application is for laser welding of corneal tissue in laser assisted penetrating keratoplasty and endothelial keratoplasty. The console is equipped with an integrated vision system. The experiment originates from a clear medical demand in order to improve the efficacy of different surgical procedures: when the prototype will be optimized, other surgical areas will be included in its application, such as neurosurgery, urology and spinal surgery.
Imaging and microsurgery procedures based on the photoacoustic effect have recently attracted much attention for cancer treatment. Light absorption in the nanosecond regime triggers thermoelastic processes that induce ultrasound emission and even cavitation. The ultrasound waves may be detected to reconstruct images, while cavitation may be exploited to kill malignant cells. The potential of gold nanorods as contrast agents for photoacoustic imaging has been extensively investigated, but still little is known about their use to trigger cavitation. Here, we investigated the influence of environment thermal properties on the ability of gold nanorods to trigger cavitation by probing the photoacoustic emission as a function of the excitation fluence. We are confident that these results will provide useful directions to the development of new strategies for therapies based on the photoacoustic effect.
Endovascular abdominal aortic aneurysms repair (EVAR) involves the minimally invasive implantation of a stent-graft
within the aorta to exclude the aneurysm from the circulation thus preventing its rupture. The feasibility of such
operation is highly dependent on the aorta morphology and in general the presence of one/both renal arteries emerging
from the aneurysm is the absolute limit for the implantation of a standard stent-graft. Consequently, classical intervention
methods involve the implantation of a custom-made graft with fenestrations, leading to extremely complicated surgeries
with high risks for the patient and high costs. Recent techniques introduced the use of standard grafts (i.e. without
fenestrations) in association with mechanical in-situ fenestration, but this procedure is limited principally by the
brittleness and low stability of the environment, in addition to the difficulty of controlling the guidance of the
endovascular tools due to the temporarily block of the blood flow. In this work we propose an innovative EVAR strategy,
which involves in-situ fenestration with a fiber guided laser tool, controlled via an electromagnetic navigation system.
The fiber is sensorized to be tracked by means of the driving system and, using a 3D model of the patient anatomy, the
surgeon can drive the fiber to the aneurysm, where the stent has been previously released, to realize the proper
fenestration(s). The design and construction of the catheter laser tool will be presented, togheter with preliminary
fenestration tests on graft-materials, including the effects due to the presence of blood and tissues.
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