Real-Time AI-Assisted Push-Broom Hyperspectral System for Precision Agriculture.

In the ever-evolving landscape of modern agriculture, the integration of advanced technologies has become indispensable for optimizing crop management and ensuring sustainable food production. This paper presents the development and implementation of a real-time AI-assisted push-broom hyperspectral system for plant identification. The push-broom hyperspectral technique, coupled with artificial intelligence, offers unprecedented detail and accuracy in crop monitoring. This paper details the design and construction of the spectrometer, including optical assembly and system integration. The real-time acquisition and classification system, utilizing an embedded computing solution, is also described. The calibration and resolution analysis demonstrates the accuracy of the system in capturing spectral data. As a test, the system was applied to the classification of plant leaves. The AI algorithm based on neural networks allows for the continuous analysis of hyperspectral data relative up to 720 ground positions at 50 fps.

3D-Printed Piezoelectret Based on Foamed Polylactic Acid for Energy-Harvesting and Sensing Applications.

Poly(lactic) acid (PLA) is a bio-compatible polymer widely used in additive manufacturing, and in the form of cellular foam it shows excellent mechanical and piezoelectric properties. This type of structure can be easily 3D-printed by Fusion Deposition Modelling (FDM) with commercially available composite filaments. In this work, we present mechanical and electrical investigations on 3D-printed low-cost and eco-friendly foamed PLA. The cellular microstructure and the foaming degree were tuned by varying extrusion temperature and flowrate. The maximum surface potential and charge stability of disk samples were found in correspondence of extrusion temperature between 230 and 240 °C with a flowrate of 53-44% when charging on a heated bed at 85 °C. The cells' morphology and correlated mechanical properties were analyzed and the measured piezoelectric d33 coefficient was found to be 212 pC/N. These findings show the importance of printing parameters and thermal treatment during the charging process in order to obtain the highest charge storage, stability and material flexibility. These results suggest that 3D-printed cellular PLA is a promising sustainable material for sensing and energy-harvesting applications.

Tissue fluidification promotes a cGAS-STING cytosolic DNA response in invasive breast cancer.

The process in which locally confined epithelial malignancies progressively evolve into invasive cancers is often promoted by unjamming, a phase transition from a solid-like to a liquid-like state, which occurs in various tissues. Whether this tissue-level mechanical transition impacts phenotypes during carcinoma progression remains unclear. Here we report that the large fluctuations in cell density that accompany unjamming result in repeated mechanical deformations of cells and nuclei. This triggers a cellular mechano-protective mechanism involving an increase in nuclear size and rigidity, heterochromatin redistribution and remodelling of the perinuclear actin architecture into actin rings. The chronic strains and stresses associated with unjamming together with the reduction of Lamin B1 levels eventually result in DNA damage and nuclear envelope ruptures, with the release of cytosolic DNA that activates a cGAS-STING (cyclic GMP-AMP synthase-signalling adaptor stimulator of interferon genes)-dependent cytosolic DNA response gene program. This mechanically driven transcriptional rewiring ultimately alters the cell state, with the emergence of malignant traits, including epithelial-to-mesenchymal plasticity phenotypes and chemoresistance in invasive breast carcinoma.

Cellular Mechanosensitivity: Validation of an Adaptable 3D-Printed Device for Microindentation.

Mechanotransduction refers to the cellular ability to sense mechanical stimuli from the surrounding environment and convert them into biochemical signals that regulate cellular physiology and homeostasis. Mechanosensitive ion channels (MSCs), especially ones of Piezo family (Piezo1 and Piezo2), play a crucial role in mechanotransduction. These transmembrane proteins directly react to mechanical cues by triggering the onset of an ionic current. The relevance of this mechanism in driving physiology and pathology is emerging, and there is a growing need for the identification of an affordable and reliable assay to measure it. Setting up a mechanosensitivity assay requires exerting a mechanical stimulus on single cells while observing the downstream effects of channels opening. We propose an open-hardware approach to stimulate single adherent cells through controlled microindentation, using a 3D-printed actuation platform. We validated the device by measuring the mechanosensitivity of a neural mice cell line where the expression level and activity of Piezo1 were genetically and pharmacologically manipulated. Moreover, this extremely versatile device could be integrated with different read-out technologies, offering a new tool to improve the understanding of mechanotransduction in living cells.

Non-contact elastography methods in mechanobiology: a point of view.

In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biomedical research. It is now widely recognized that living cells respond not only to chemical stimuli (for example drugs), but they are also able to decipher mechanical cues, such as the rigidity of the underlying matrix or the presence of shear forces. Probing the viscoelastic properties of cells and their local microenvironment with sub-micrometer resolution is required to study this complex interplay and dig deeper into the mechanobiology of single cells. Current approaches to measure mechanical properties of adherent cells mainly rely on the exploitation of miniaturized indenters, to poke single cells while measuring the corresponding deformation. This method provides a neat implementation of the everyday approach to measure mechanical properties of a material, but it typically results in a very low throughput and invasive experimental protocol, poorly translatable towards three-dimensional living tissues and biological constructs. To overcome the main limitations of nanoindentation experiments, a radical paradigm change is foreseen, adopting next generation contact-less methods to measure mechanical properties of biological samples with sub-cell resolution. Here we briefly introduce the field of single cell mechanical characterization, and we concentrate on a promising high resolution optical elastography technique, Brillouin spectroscopy. This non-contact technique is rapidly emerging as a potential breakthrough innovation in biomechanics, but the application to single cells is still in its infancy.

Bioinspired Reactive Interfaces Based on Layered Double Hydroxides-Zn Rich Hydroxyapatite with Antibacterial Activity.

This work is focused on the preparation and multi-technique characterization of potentially biocompatible reactive interfaces obtained by combining layered double hydroxides (LDHs) and hydroxyapatite (HA). Antimicrobial and osteoinductive metallic ions as Zn2+ and Ga3+ were chosen as intralayer constituents of LDH to obtain ZnAl and ZnAlGa systems. These LDHs, exchanged with dihydrogenphosphate anions, promoted the precipitation of HA on the LDH surface yielding HA@LDH composites. X-ray diffraction quantitative analysis, through the Rietveld refinement method, coupled with elemental analysis and micro-Raman spectroscopy showed the formation of a mixed Ca-Zn HA phase. Scanning electron microscopy revealed that HA, in the presence of LDH, grew preferentially along its a-axis, thus crystallizing mainly in the form of flake crystals. LDH and HA@LDH composites showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at not cytotoxic concentrations for human osteoblasts (hFob 1.19), especially when Ga cations were present in the LDH structure. The effect of the presence of HA in the composites on the bone-bonding ability and on human osteoblast proliferation was also investigated. The HA seemed to reduce the toxicity of the LDH toward human osteoblast while did not affect the bone-bonding ability. This multidisciplinary study provides the bio-chemical, structural characterization of new LDH and HA@LDH composites, evaluating also their bioactivity to be potentially applicable to titanium-based prostheses.

Bio-mechanical characterization of a CAD/CAM PMMA resin for digital removable prostheses.

OBJECTIVE: To compare the mechanical and biological features of a polymethylmethacrylate (PMMA) disc for CAD/CAM prostheses (test samples, TG) with a traditional resin (control samples, CG). METHODS: Mechanical analysis was performed using Dynamic Mechanical Analysis (DMA) and Brillouin's micro-spectroscopy. Human keratinocyte morphology and adhesion were analyzed by scanning electronic microscopy (SEM), cytotoxicity by the MTT assay, apoptosis by flow cytometry and p53, p21 and bcl2 gene expression by real time PCR. RESULTS: TG exhibited a higher elastic modulus than CG (range 5100-5500 ± 114.3 MPa vs 3000-3300 ± 99.97 MPa). The Brillouin frequency was found at ωB= (15.50 ± 0.05) GHz for TG and at ωB_1 = (15.50 ± 0.05) GHz and ωB_2 = (15.0 ± 0.1) GHz for CG where two peaks were always present independently of the sample point. SEM analysis revealed that keratinocytes on TG disks appeared to be flattened with lamellipodia. Keratinocytes on CG disks rose above the substrate with cytoplasmatic filaments. MTT viability data at 3 h and 24 h showed TG was significantly less cytotoxic than CG (p < 0.001). No significant differences emerged in apoptosis on CG and TG. Real-time PCR showed p53 expression increased after 3 h by about 9-fold in keratinocytes on TG (p < 0.001) and about 5-fold in those on CG (p < 0.001). High p53 expression persisted after 24 h on both disks. No significant variations were observed in p21 and bcl2 expression at any time-point. SIGNIFICANCE: PMMA resins, as used in CAD/CAM technology, displayed suitable biocompatible and mechanical properties for removable prostheses.

Transition across a sharp interface: Data from Raman and Brillouin imaging spectroscopy.

Brillouin and Raman imaging are powerful techniques for the investigation of complex materials and they are widely used in material science and biophysics [1], [2], [3], [4], [5], [6], [7]. When dealing with microstructures, the results interpretation requires an accurate understanding of the interaction processes in presence of acoustic and chemical boundaries between different materials [8], [9], [10], [11], [12], [13], [14], [15]. The data here reported are obtained while scanning with sub-micron resolution the sharp interfaces between vitreous-SiO2/Water and Polyethylene (PET)/Glycerol. Molecular and acoustic vibrations were observed by means of a recently developed micro-spectrometer, which acquires simultaneously Raman and Brillouin spectra on the same point with high spatial and spectral resolution [3]. Two external optic configurations were adopted in order to evidence the dependency of the measurements on the optical scattering volume. The evolution of the detected phonon modes, propagating and not propagating, is obtained by a direct observation of the raw data for the two interfaces, which present different acoustic mismatch. These experimental records can be exploited by researchers employing Raman and Brillouin imaging to discuss the resolution limit of the techniques and to compare the effect of different experimental set-ups. Moreover, thanks to their high spectral resolution they can be useful to researchers working on acoustic phonon transport at interfaces to model the dependency of transmission of long wavelength phonons on the acoustic mismatch.

Correlative Brillouin and Raman spectroscopy data acquired on single cells.

The distribution of chemical species and the mechanical modulation inside a single cell or tissue are of fundamental importance to characterize their physiological activity or their pathological conditions [1-4]. Here we analyse these properties by means of label free, non invasive, spectroscopic methods. In particular, we use a recently developed micro-spectrometer, which acquires simultaneously Raman and Brillouin spectra on the same point with subcellular resolution [5]. The techniques ability to analyse the chemical composition and the mechanical properties of single cells has been tested on NIH/3T3 murine fibroblast cells grown in adhesion on silicon substrates. Here we report the data acquired from fixed cells after their oncogenic transformation. Mechanical and chemical evolution is evident by direct inspection of raw data. Sharing our experimental records can be valuable for researchers interested in the analysis of single cells by Raman and Brillouin spectroscopy in order: i) to compare data acquired by different set-ups and ii) to correctly model the fitting functions.

Non-contact mechanical and chemical analysis of single living cells by microspectroscopic techniques.

Innovative label-free microspectroscopy, which can simultaneously collect Brillouin and Raman signals, is used to characterize the viscoelastic properties and chemical composition of living cells with sub-micrometric resolution. The unprecedented statistical accuracy of the data combined with the high-frequency resolution and the high contrast of the recently built experimental setup permits the study of single living cells immersed in their buffer solution by contactless measurements. The Brillouin signal is deconvoluted in the buffer and the cell components, thereby revealing the mechanical heterogeneity inside the cell. In particular, a 20% increase is observed in the elastic modulus passing from the plasmatic membrane to the nucleus as distinguished by comparison with the Raman spectroscopic marker. Brillouin line shape analysis is even more relevant for the comparison of cells under physiological and pathological conditions. Following oncogene expression, cells show an overall reduction in the elastic modulus (15%) and apparent viscosity (50%). In a proof-of-principle experiment, the ability of this spectroscopic technique to characterize subcellular compartments and distinguish cell status was successfully tested. The results strongly support the future application of this technique for fundamental issues in the biomedical field.

Raman micro-spectroscopy: a powerful tool for the monitoring of dynamic supramolecular changes in living cells.

Cellular imaging techniques have become powerful tools in cell biology. With respect to others, the techniques based on vibrational spectroscopy present a clear advantage: the molecular composition and the modification of subcellular compartments can be obtained in label-free conditions. In fact, from the evolution of positions, intensities and line widths of Raman and infrared bands in the cell spectra, characteristic information on cellular activities can be achieved, and particularly, cellular death can be investigated. In this work we present the time evolution of the Raman spectra of single live Jurkat cells (T-lymphocyte) by looking at the high frequency part of their Raman spectra, that is the CH stretching region, around 3000cm(-1). In particular, investigation into the composition or rearrangement of CH bounds, markers of cellular membrane fatty acids, can represent an important method to study and to recognize cell death. The experimental procedure we used, together with the analysis of these high frequency vibrational bands, may represent a new, improved and advantageous approach to this kind of study.