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Diatomaceous earth, or diatomite, is produced through the accumulation of diatom (Bacillariophyceae) skeletons (i.e. cell walls called frustules) made of amorphous silica. The porous, highly symmetrical structure and microscopic size of diatom cell walls make them ideal constituents of sensing devices and analytical chips. Here, we propose chemical methods to purify diatom frustules extracted from diatomaceous earth. Using photo deposition techniques, we grow gold nanoparticles on the surface of diatom skeletons and within the pores of the skeletons, where the size and density of nanoparticles can be controlled by changing the parameters of the synthesis. Resulting devices have an internal porous structure that can harvest molecules from a solution, and an external shell of gold nanoparticles that amplifies the electromagnetic field generated by the measurement laser in Raman or other spectroscopies. The combination of these effects enables the analysis of biological specimens, chemical analytes and pollutants in extremely low abundance ranges. The devices were demonstrated in the analysis of Bovine Serum Albumin in water with a concentration of 100 aM, and mineral oil with a concentration of 50 ppm. Keywords: Diatomite, Diatoms, Photo-deposition, Gold nanoparticles, SERS, Bio-sensors

Electroless deposition on patterned silicon substrates enables the formation of metal nanomaterials with tight control over their size and shape. In the technique, metal ions are transported by diffusion from a solution to the active sites of an autocatalytic substrate where they are reduced as metals upon contact. Here, using diffusion limited aggregation models and numerical simulations, we derived relationships that correlate the cluster size distribution to the total mass of deposited particles. We found that the ratio ξ between the rates of growth of two different metals depends on the ratio γ between the rates of growth of clusters formed by those metals through the linearity law ξ = 14(γ − 1). We then validated the model using experiments. Different from other methods, the model derives k using as input the geometry of metal nanoparticle clusters, decoded by SEM or AFM images of samples, and a known reference.

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 &micro, L/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 &micro, m/min, comparable with the rates present in scientific literature.

Porous silicon is a nano material in which pores with different sizes, densities and depths are infiltrated in conventional silicon imparting it augmented properties including biodegradability, biocompatibility, photoluminescence. Here, we realized porous silicon substrates in which the pore size and the fractal dimension were varied over a significant range. We loaded the described substrates with a PtCl(O,O'-acac)(DMSO) antitumor drug and determined its release profile as a function of pore size over time up to 15days. We observed that the efficacy of delivery augments with the pore size moving from small (~8nm, efficiency of delivery ~0.2) to large (~55nm, efficiency of delivery ~0.7). Then, we verified the adhesion of MCF-7 breast cancer cells on the described substrates with and without the administration of the antitumor drug. This permitted to decouple and understand the coincidental effects of nano-topography and a controlled dosage of drugs on cell adhesion and growth. While large pore sizes guarantee elevated drug dosages, large fractal dimensions boost cell adhesion on a surface. For the particular case of tumor cells and the delivery of an anti-tumor drug, substrates with a small fractal dimension and large pore size hamper cell growth. The competition between nano-topography and a controlled dosage of drugs may either accelerate or block the adhesion of cells on a nanostructured surface, for applications in tissue engineering, regenerative medicine, personalized lab-on-a-chips, and the rational design of implantable drug delivery systems. Display Omitted We realized porous silicon substrates with a varying pore size and fractal dimension.We loaded the substrates with an antitumor drug and determined its release profile over time.We verified the adhesion of MCF-7 cancer cells on the porous substrates.We decoupled the effects of nano-topography and drug delivery on cell adhesion.Large pore sizes boost drug release, large fractal dimensions accelerate cell adhesion.

Secretome of primary cultures is an accessible source of biological markers compared to more complex and less decipherable mixtures such as serum or plasma. The protonation state (PS) of secretome reflects the metabolism of cells and can be used for cancer early detection. Here, we demonstrate a superhydrophobic organic electrochemical device that measures PS in a drop of secretome derived from liquid biopsies. Using data from the sensor and principal component analysis (PCA), we developed algorithms able to efficiently discriminate tumour patients from non-tumour patients. We then validated the results using mass spectrometry and biochemical analysis of samples. For the 36 patients across three independent cohorts, the method identified tumour patients with high sensitivity and identification as high as 100% (no false positives) with declared subjects at-risk, for sporadic cancer onset, by intermediate values of PS. This assay could impact on cancer risk management, individual’s diagnosis and/or help clarify risk in healthy populations., Diagnostics: Proton state of secreted proteins in blood helps identify cancer A blood test that measures whether molecules secreted by cells contain titratable proton atoms can accurately discriminate between patients who have cancer and those who don’t. Titratable species may in turn influence the protonation state of a solution, i.e. the number of protons added to and the net charge of that solution. A team led by Natalia Malara from University Magna Graecia in Catanzaro, Italy and Enzo Di Fabrizio from the King Abdullah University of Science and Technology in Thuwal, Saudi Arabia, Francesco Gentile from the University Federico II in Naples, Italy, and Nicola Coppedè from the Institute of Materials for Electronics and Magnetism in Parma, Italy, created an eletrochemical device that can detect faulty metabolism by quantifying the proportion of secreted proteins with and without extra protons—an indicator of abnormal cell division, proliferation and invasion. The researchers tested the device on blood samples from patients with solid tumors and healthy controls. The method identified cancer patients with a high degree of accuracy. If the findings are confirmed in larger trials, the test could help with the screening, diagnosis and management of cancer.

Diatom shells are a natural, theoretically unlimited material composed of silicon dioxide, with regular patterns of pores penetrating through their surface. For their characteristics, diatom shells show promise to be used as low cost, highly efficient drug carriers, sensor devices or other micro-devices. Here, we demonstrate diatom shells functionalized with gold nanoparticles for the harvesting and detection of biological analytes (bovine serum albumin—BSA) and chemical pollutants (mineral oil) in low abundance ranges, for applications in bioengineering, medicine, safety, and pollution monitoring. Electronic supplementary material The online version of this article (10.1186/s11671-018-2507-4) contains supplementary material, which is available to authorized users.

Neural cells are the smallest building blocks of the central and peripheral nervous systems. Information in neural networks and cell-substrate interactions have been heretofore studied separately. Understanding whether surface nano-topography can direct nerve cells assembly into computational efficient networks may provide new tools and criteria for tissue engineering and regenerative medicine. In this work, we used information theory approaches and functional multi calcium imaging (fMCI) techniques to examine how information flows in neural networks cultured on surfaces with controlled topography. We found that substrate roughness S a affects networks topology. In the low nano-meter range, S a = 0–30 nm, information increases with S a . Moreover, we found that energy density of a network of cells correlates to the topology of that network. This reinforces the view that information, energy and surface nano-topography are tightly inter-connected and should not be neglected when studying cell-cell interaction in neural tissue repair and regeneration.

The study and the comprehension of the mechanism of cell adhesion and cell interaction with a substrate is a key point when biology and medicine meet engineering. This is the case of several biomedical applications, from regenerative medicine and tissue engineering to lab on chip and many others, in which the realization of the appropriate artificial surface allows the control of cell adhesion and proliferation.In this context, we aimed to design and develop a fabrication method of mesoporous (MeP) silicon substrates, doped with gold nanoparticles, in which we combine the capability of porous surfaces to support cell adhesion with the SERS capabilities of gold nanoparticles, to understand the chemical mechanisms of cell/surface interaction.MeP Si surfaces were realized by anodization of a Si wafer, creating the device for cell adhesion and growth. Gold nanoparticles were deposited on porous silicon by an electroless technique. We thus obtained devices with superior SERS capabilities, whereby cell activity may be controlled using Raman spectroscopy. MCF-7 breast cancer cells were cultured on the described substrates and SERS maps revealing the different expression and distribution of adhesion molecules were obtained by Raman spectroscopic analyses. Display Omitted designing and developing of a fabrication method of mesoporous (MeP) silicon substrates decorated with gold nanoparticlesthese devices are able to support cell adhesion and proliferation and simultaneously they works as SERS substratesSERS Raman analysis of cells cultured on MeP Si substrates provide indication about cells behaviour on them.

Recent progresses in nanotechnology fabrication gives the opportunity to build highly functional nano-devices. 3D structures based on noble metals or covered by them can be realized down to the nano-scales, obtaining different devices with the functionalities of plasmonic nano-lenses or nano-probes. Here, nano-cones decorated with silver nano-grains were fabricated using advanced nano-fabrication techniques. In fabricating the cones, the angle of the apex was varied over a significant range and, in doing so, different geometries were realized. In depositing the silver nano-particles, the concentration of solution was varied, whereby different growth conditions were realized. The combined effect of tip geometry and growth conditions influences the size and distribution of the silver nano grains. The tips have the ability to guide or control the growth of the grains, in the sense that the nano-particles would preferentially distribute along the cone, and especially at the apex of the cone, with no o minor concentration effects on the substrate. The arrangement of metallic nano-particles into three-dimensional (3D) structures results in a Surface Enhanced Raman Spectroscopy (SERS) device with improved interface with analytes compared to bi-dimensional arrays of metallic nanoparticles. In the future, similar devices may find application in microfluidic devices, and in general in flow chambers, where the system can be inserted as to mimic a a nano-bait, for the recognition of specific biomarkers, or the manipulation and chemical investigation of single cells directly in native environments with good sensitivity, repeatability and selectivity.