Correlative Raman-Electron-Light (CREL) Microscopy Analysis of Lipid Droplets in Melanoma Cancer Stem Cells.

Among all neoplasms, melanoma is characterized by a very high percentage of cancer stem cells (CSCs). Several markers have been proposed for their identification, and lipid droplets (LDs) are among them. Different techniques are used for their characterization such as mass spectrometry, imaging techniques, and vibrational spectroscopies. Some emerging experimental approaches for the study of LDs are represented by correlative light-electron microscopy and by correlative Raman imaging-scanning electron microscopy (SEM). Based on these scientific approaches, we developed a novel methodology (CREL) by combining Raman micro-spectroscopy, confocal fluorescence microscopy, and SEM coupled with an energy-dispersive X-ray spectroscopy module. This procedure correlated cellular morphology, chemical properties, and spatial distribution from the same region of interest, and in this work, we presented the application of CREL for the analysis of LDs within patient-derived melanoma CSCs (MCSCs).

Microfluidics for 3D Cell and Tissue Cultures: Microfabricative and Ethical Aspects Updates.

The necessity to improve in vitro cell screening assays is becoming ever more important. Pharmaceutical companies, research laboratories and hospitals require technologies that help to speed up conventional screening and therapeutic procedures to produce more data in a short time in a realistic and reliable manner. The design of new solutions for test biomaterials and active molecules is one of the urgent problems of preclinical screening and the limited correlation between in vitro and in vivo data remains one of the major issues. The establishment of the most suitable in vitro model provides reduction in times, costs and, last but not least, in the number of animal experiments as recommended by the 3Rs (replace, reduce, refine) ethical guiding principles for testing involving animals. Although two-dimensional (2D) traditional cell screening assays are generally cheap and practical to manage, they have strong limitations, as cells, within the transition from the three-dimensional (3D) in vivo to the 2D in vitro growth conditions, do not properly mimic the real morphologies and physiology of their native tissues. In the study of human pathologies, especially, animal experiments provide data closer to what happens in the target organ or apparatus, but they imply slow and costly procedures and they generally do not fully accomplish the 3Rs recommendations, i.e., the amount of laboratory animals and the stress that they undergo must be minimized. Microfluidic devices seem to offer different advantages in relation to the mentioned issues. This review aims to describe the critical issues connected with the conventional cells culture and screening procedures, showing what happens in the in vivo physiological micro and nano environment also from a physical point of view. During the discussion, some microfluidic tools and their components are described to explain how these devices can circumvent the actual limitations described in the introduction.

Direct Visualization and Identification of Membrane Voltage-Gated Sodium Channels from Human iPSC-Derived Neurons by Multiple Imaging and Light Enhanced Spectroscopy.

In this study, transmission electron microscopy atomic force microscopy, and surface enhanced Raman spectroscopy are combined through a direct imaging approach, to gather structural and chemical information of complex molecular systems such as ion channels in their original plasma membrane. Customized microfabricated sample holder allows to characterize Nav channels embedded in the original plasma membrane extracted from neuronal cells that are derived from healthy human induced pluripotent stem cells. The identification of the channels is accomplished by using two different approaches, one of them widely used in cryo-EM (the particle analysis method) and the other based on a novel Zernike Polynomial expansion of the images bitmap. This approach allows to carry out a whole series of investigations, one complementary to the other, on the same sample, preserving its state as close as possible to the original membrane configuration.

Micro/Nanopatterned Superhydrophobic Surfaces Fabrication for Biomolecules and Biomaterials Manipulation and Analysis.

Superhydrophobic surfaces display an extraordinary repulsion to water and water-based solutions. This effect emerges from the interplay of intrinsic hydrophobicity of the surface and its morphology. These surfaces have been established for a long time and have been studied for decades. The increasing interest in recent years has been focused towards applications in many different fields and, in particular, biomedical applications. In this paper, we review the progress achieved in the last years in the fabrication of regularly patterned superhydrophobic surfaces in many different materials and their exploitation for the manipulation and characterization of biomaterial, with particular emphasis on the issues affecting the yields of the fabrication processes and the quality of the manufactured devices.

Raman Spectroscopic Stratification of Multiple Myeloma Patients Based on Exosome Profiling.

Multiple myeloma (MM) is a hematological malignancy characterized by abnormal plasma cell proliferation within the bone marrow which leads to progressive bone marrow failure, skeletal osteolytic lesions, and renal insufficiency, thus severely affecting the quality of life. MM is always preceded by monoclonal gammopathy of uncertain significance (MGUS), which progresses to asymptomatic-MM (aMM) or symptomatic-MM (sMM) at a rate of 1% per year. Despite impressive progress in the therapy of the disease, MM remains incurable. Based on these premises, the identification of biomarkers of MGUS progression to MM is a crucial issue in disease management. In this regard, exosomes (EXs) and their precious biomolecular cargo could play a pivotal role in MM detection, stratification, and follow-up. Raman spectroscopy, a label- and manipulation-free technique, and its enhanced version, surface-enhanced Raman spectroscopy (SERS), have been used for characterizing MGUS, aMM, and sMM patient-derived EXs. Here, we have demonstrated the capability of Raman spectroscopy for discriminating EXs along the progression from MGUS to aMM and sMM, thus providing useful clinical indications for patient care. The used SERS devices, based on random nanostructures, have shown good potential in terms of sensitivity, but further developments are needed for achieving reproducible and quantitative SERS results.

A Disposable Passive Microfluidic Device for Cell Culturing.

In this work, a disposable passive microfluidic device for cell culturing that does not require any additional/external pressure sources is introduced. By regulating the height of fluidic columns and the aperture and closure of the source wells, the device can provide different media and/or drug flows, thereby allowing different flow patterns with respect to time. The device is made of two Polymethylmethacrylate (PMMA) layers fabricated by micro-milling and solvent assisted bonding and allows us to ensure a flow rate of 18.6 µl/ℎ - 7%/day, due to a decrease of the fluid height while the liquid is driven from the reservoirs into the channels. Simulations and experiments were conducted to characterize flows and diffusion in the culture chamber. Melanoma tumor cells were used to test the device and carry out cell culturing experiments for 48 hours. Moreover, HeLa, Jurkat, A549 and HEK293T cell lines were cultivated successfully inside the microfluidic device for 72 hours.

Influence of the Fabrication Accuracy of Hot-Embossed PCL Scaffolds on Cell Growths.

Polycaprolactone (PCL) is a biocompatible and biodegradable polymer widely used for the realization of 3D scaffold for tissue engineering applications. The hot embossing technique (HE) allows the obtainment of PCL scaffolds with a regular array of micro pillars on their surface. The main drawback affecting this kind of micro fabrication process is that such structural superficial details can be damaged when detaching the replica from the mold. Therefore, the present study has focused on the optimization of the HE processes through the development of an analytical model for the prediction of the demolding force as a function of temperature. This model allowed calculating the minimum demolding force to obtain regular micropillars without defects. We demonstrated that the results obtained by the analytical model agree with the experimental data. To address the importance of controlling accurately the fabricated microstructures, we seeded on the PCL scaffolds human stromal cell line (HS-5) and monocytic leukemia cell line (THP-1) to evaluate how the presence of regular or deformed pillars affect cells viability. In vitro viability results, scanning electron and fluorescence microscope imaging analysis show that the HS-5 preferentially grows on regular microstructured surfaces, while the THP-1 on irregular microstructured ones.

Emerging Designs of Electronic Devices in Biomedicine.

A long-standing goal of nanoelectronics is the development of integrated systems to be used in medicine as sensor, therapeutic, or theranostic devices. In this review, we examine the phenomena of transport and the interaction between electro-active charges and the material at the nanoscale. We then demonstrate how these mechanisms can be exploited to design and fabricate devices for applications in biomedicine and bioengineering. Specifically, we present and discuss electrochemical devices based on the interaction between ions and conductive polymers, such as organic electrochemical transistors (OFETs), electrolyte gated field-effect transistors (FETs), fin field-effect transistor (FinFETs), tunnelling field-effect transistors (TFETs), electrochemical lab-on-chips (LOCs). For these systems, we comment on their use in medicine.

Kinetic Rate Constants of Gold Nanoparticle Deposition on Silicon.

We fabricated gold nanoparticles on nanoporous silicon microparticles using electroless deposition in a hydrofluoric acid solution containing gold chloride. The reaction was followed by UV spectrometer analysis of the absorbance of the solution (proportional to the nanoparticle concentration) for two temperatures (20 and 50 °C). The results indicate that the process is autocatalytic, described by a pseudo-first-order reaction, the apparent rate constant kobs of which was determined by utilizing UV spectrometer data. We found that the reaction rate constant at 20 °C is 7 × 10-3 s-1 and that at 50 °C is 2.9 × 10-2 s-1. Scanning electron microscope (SEM) analysis of samples and diffusion-limited aggregation (DLA) simulations were used to validate the results. This study aims to resolve the kinetics of the electroless deposition of gold on silicon at the nanoscale, in the present state of art missing a quantitative characterization, for certain conditions of growth and given values of temperature and concentration of the reagents. Results may have applications to the synthesis of gold nanoparticles and their use as nanosensors, drug delivery systems, or metal nanometamaterials with advanced optical properties.

A Passive Microfluidic Device for Chemotaxis Studies.

This work presents a disposable passive microfluidic system, allowing chemotaxis studies, through the generation of a concentration gradient. The device can handle liquid flows without an external supply of pressure or electric gradients, but simply using gravity force. It is able to ensure flow rates of 10 µL/h decreasing linearly with 2.5% in 24 h. The device is made of poly(methylmethacrylate) (PMMA), a biocompatible material, and it is fabricated by micro-milling and solvent assisted bonding. It is assembled into a mini incubator, designed properly for cell biology studies in passive microfluidic devices, which provides control of temperature and humidity levels, a contamination-free environment for cells with air and 5% of CO2. Furthermore, the mini incubator can be mounted on standard inverted optical microscopes. By using our microfluidic device integrated into the mini incubator, we are able to evaluate and follow in real-time the migration of any cell line to a chemotactic agent. The device is validated by showing cell migration at a rate of 0.36 µm/min, comparable with the rates present in scientific literature.

Key Role of Cytochrome C for Apoptosis Detection Using Raman Microimaging in an Animal Model of Brain Ischemia with Insulin Treatment.

Brain ischemia represents a leading cause of death and disability in industrialized countries. To date, therapeutic intervention is largely unsatisfactory and novel strategies are required for getting better protection of neurons injured by cerebral blood flow restriction. Recent evidence suggests that brain insulin leads to protection of neuronal population undergoing apoptotic cell death via modulation of oxidative stress and mitochondrial cytochrome c (CytC), an effect to be better clarified. In this work, we investigate on the effect of insulin given intracerebroventricular (ICV) before inducing a transient global ischemia by bilateral occlusion of the common carotid arteries (BCCO) in Mongolian gerbils (MG). The transient (3 min) global ischemia in MG is observed to produce neurodegenerative effect mainly into CA3 hippocampal region, 72 h after cerebral blood restriction. Intracerebroventricular microinfusion of insulin significantly prevents the apoptosis of CA3 hippocampal neurons. Histological observation, after hematoxylin and eosin staining, puts in evidence the neuroprotective role of insulin, but Raman microimaging provides a clearer insight in the CytC mechanism underlying the apoptotic process. Above all, CytC has been revealed to be an outstanding, innate Raman marker for monitoring the cells status, thanks to its resonant scattering at 530 nm of incident wavelength and to its crucial role in the early stages of cells apoptosis. These data support the hypothesis of an insulin-dependent neuroprotection and antiapoptotic mechanism occurring in the brain of MG undergoing transient brain ischemia. The observed effects occurred without any peripheral change on serum glucose levels, suggesting an alternative mechanism of insulin-induced neuroprotection.

Waveguiding and SERS Simplified Raman Spectroscopy on Biological Samples.

Biomarkers detection at an ultra-low concentration in biofluids (blood, serum, saliva, etc.) is a key point for the early diagnosis success and the development of personalized therapies. However, it remains a challenge due to limiting factors like (i) the complexity of analyzed media, and (ii) the aspecificity detection and the poor sensitivity of the conventional methods. In addition, several applications require the integration of the primary sensors with other devices (microfluidic devices, capillaries, flasks, vials, etc.) where transducing the signal might be difficult, reducing performances and applicability. In the present work, we demonstrate a new class of optical biosensor we have developed integrating an optical waveguide (OWG) with specific plasmonic surfaces. Exploiting the plasmonic resonance, the devices give consistent results in surface enhanced Raman spectroscopy (SERS) for continuous and label-free detection of biological compounds. The OWG allows driving optical signals in the proximity of SERS surfaces (detection area) overcoming spatial constraints, in order to reach places previously optically inaccessible. A rutile prism couples the remote laser source to the OWG, while a Raman spectrometer collects the SERS far field scattering. The present biosensors were implemented by a simple fabrication process, which includes photolithography and nanofabrication. By using such devices, it was possible to detect cell metabolites like Phenylalanine (Phe), Adenosine 5-triphosphate sodium hydrate (ATP), Sodium Lactate, Human Interleukin 6 (IL6), and relate them to possible metabolic pathway variation.

Development of 3D PVA scaffolds for cardiac tissue engineering and cell screening applications.

The aim of this study was the design of a 3D scaffold composed of poly(vinyl) alcohol (PVA) for cardiac tissue engineering (CTE) applications. The PVA scaffold was fabricated using a combination of gas foaming and freeze-drying processes that did not need any cross-linking agents. We obtained a biocompatible porous matrix with excellent mechanical properties. We measured the stress-strain curves of the PVA scaffolds and we showed that the elastic behavior is similar to that of the extracellular matrix of muscles. The SEM observations revealed that the scaffolds possess micro pores having diameters ranging from 10 µm to 370 µm that fit to the dimensions of the cells. A further purpose of this study was to test scaffolds ability to support human induced pluripotent stem cells growth and differentiation into cardiomyocytes. As the proliferation tests show, the number of live stem cells on the scaffold after 12 days was increased with respect to the initial number of cells, revealing the cytocompatibility of the substrate. In addition, the differentiated cells on the PVA scaffolds expressed anti-troponin T, a marker specific of the cardiac sarcomere. We demonstrated the ability of the cardiomyocytes to pulse within the scaffolds. In conclusion, the developed scaffold show the potential to be used as a biomaterial for CTE applications.

Two sides of the same coin? Unraveling subtle differences between human embryonic and induced pluripotent stem cells by Raman spectroscopy.

BACKGROUND: Human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells, hold enormous promise for many biomedical applications, such as regenerative medicine, drug testing, and disease modeling. Although induced pluripotent stem cells resemble embryonic stem cells both morphologically and functionally, the extent to which these cell lines are truly equivalent, from a molecular point of view, remains controversial. METHODS: Principal component analysis and K-means cluster analysis of collected Raman spectroscopy data were used for a comparative study of the biochemical fingerprint of human induced pluripotent stem cells and human embryonic stem cells. The Raman spectra analysis results were further validated by conventional biological assays. RESULTS: Raman spectra analysis revealed that the major difference between human embryonic stem cells and induced pluripotent stem cells is due to the nucleic acid content, as shown by the strong positive peaks at 785, 1098, 1334, 1371, 1484, and 1575 cm-1, which is enriched in human induced pluripotent stem cells. CONCLUSIONS: Here, we report a nonbiological approach to discriminate human induced pluripotent stem cells from their native embryonic stem cell counterparts.

Fabrication and Applications of Micro/Nanostructured Devices for Tissue Engineering.

Nanotechnology allows the realization of new materials and devices with basic structural unit in the range of 1-100 nm and characterized by gaining control at the atomic, molecular, and supramolecular level. Reducing the dimensions of a material into the nanoscale range usually results in the change of its physiochemical properties such as reactivity, crystallinity, and solubility. This review treats the convergence of last research news at the interface of nanostructured biomaterials and tissue engineering for emerging biomedical technologies such as scaffolding and tissue regeneration. The present review is organized into three main sections. The introduction concerns an overview of the increasing utility of nanostructured materials in the field of tissue engineering. It elucidates how nanotechnology, by working in the submicron length scale, assures the realization of a biocompatible interface that is able to reproduce the physiological cell-matrix interaction. The second, more technical section, concerns the design and fabrication of biocompatible surface characterized by micro- and submicroscale features, using microfabrication, nanolithography, and miscellaneous nanolithographic techniques. In the last part, we review the ongoing tissue engineering application of nanostructured materials and scaffolds in different fields such as neurology, cardiology, orthopedics, and skin tissue regeneration.

Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers.

In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels- where the cells can flow one-by-one -, allowing single cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm of the each cell. Experiments are performed on red blood cells (RBCs), peripheral blood lymphocytes (PBLs) and myelogenous leukemia tumor cells (K562).

Detection of single amino acid mutation in human breast cancer by disordered plasmonic self-similar chain.

Control of the architecture and electromagnetic behavior of nanostructures offers the possibility of designing and fabricating sensors that, owing to their intrinsic behavior, provide solutions to new problems in various fields. We show detection of peptides in multicomponent mixtures derived from human samples for early diagnosis of breast cancer. The architecture of sensors is based on a matrix array where pixels constitute a plasmonic device showing a strong electric field enhancement localized in an area of a few square nanometers. The method allows detection of single point mutations in peptides composing the BRCA1 protein. The sensitivity demonstrated falls in the picomolar (10(-12) M) range. The success of this approach is a result of accurate design and fabrication control. The residual roughness introduced by fabrication was taken into account in optical modeling and was a further contributing factor in plasmon localization, increasing the sensitivity and selectivity of the sensors. This methodology developed for breast cancer detection can be considered a general strategy that is applicable to various pathologies and other chemical analytical cases where complex mixtures have to be resolved in their constitutive components.

Mechanical stress downregulates MHC class I expression on human cancer cell membrane.

In our body, cells are continuously exposed to physical forces that can regulate different cell functions such as cell proliferation, differentiation and death. In this work, we employed two different strategies to mechanically stress cancer cells. The cancer and healthy cell populations were treated either with mechanical stress delivered by a micropump (fabricated by deep X-ray nanolithography) or by ultrasound wave stimuli. A specific down-regulation of Major Histocompatibility Complex (MHC) class I molecules expression on cancer cell membrane compared to different kinds of healthy cells (fibroblasts, macrophages, dendritic and lymphocyte cells) was observed, stimulating the cells with forces in the range of nano-newton, and pressures between 1 and 10 bar (1 bar = 100.000 Pascal), depending on the devices used. Moreover, Raman spectroscopy analysis, after mechanical treatment, in the range between 700-1800 cm(-1), indicated a relative concentration variation of MHC class I. PCA analysis was also performed to distinguish control and stressed cells within different cell lines. These mechanical induced phenotypic changes increase the tumor immunogenicity, as revealed by the related increased susceptibility to Natural Killer (NK) cells cytotoxic recognition.

Folic acid functionalized surface highlights 5-methylcytosine-genomic content within circulating tumor cells.

Although the detection of methylated cell free DNA represents one of the most promising approaches for relapse risk assessment in cancer patients, the low concentration of cell-free circulating DNA constitutes the biggest obstacle in the development of DNA methylation-based biomarkers from blood. This paper describes a method for the measurement of genomic methylation content directly on circulating tumor cells (CTC), which could be used to deceive the aforementioned problem. Since CTC are disease related blood-based biomarkers, they result essential to monitor tumor's stadiation, therapy, and early relapsing lesions. Within surface's bio-functionalization and cell's isolation procedure standardization, the presented approach reveals a singular ability to detect high 5-methylcytosine CTC-subset content in the whole CTC compound, by choosing folic acid (FA) as transducer molecule. Sensitivity and specificity, calculated for FA functionalized surface (FA-surface), result respectively on about 83% and 60%. FA-surface, allowing the detection and characterization of early metastatic dissemination, provides a unique advance in the comprehension of tumors progression and dissemination confirming the presence of CTC and its association with high risk of relapse. This functionalized surface identifying and quantifying high 5-methylcytosine CTC-subset content into the patient's blood lead significant progress in cancer risk assessment, also providing a novel therapeutic strategy.

Selective on site separation and detection of molecules in diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles.

Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film adsorbs the low molecular weight content of the solution and, (iii) at a smaller nanometric scale, the aggregates of silver nano-particles would measure the target molecules with unprecedented sensitivity. In the results, we demonstrated how this scheme can be utilized to isolate and detect small molecules in a diluted solution in very low abundance ranges. The presented platform, coupled to Raman or other spectroscopy techniques, is a realistic candidate for the protein expression profiling of biological fluids.