Nano-roughened Surface Research Articles

Single-cell fluid-based force spectroscopy reveals near lipid size nano-topography effects on neural cell adhesion.

Nano-roughness has shown great potential in enhancing high-fidelity electrogenic cell interfaces, owing to its characteristic topography comparable to proteins and lipids, which influences a wide range of cellular mechanical responses. Gaining a comprehensive understanding of how cells respond to nano-roughness at the single-cell level is not only imperative for implanted devices but also essential for tissue regeneration and interaction with complex biomaterial surfaces. In this study, we quantify cell adhesion and biomechanics of single cells to nano-roughened surfaces by measuring neural cell adhesion and biomechanics via fluidic-based single-cell force spectroscopy (SCFS). For this, we introduce nanoscale topographical features on polyimide (PI) surfaces achieving roughness up to 25 nm without chemical modifications. Initial adhesion experiments show cell-specific response to nano-roughness for neuroblastoma cells (SH-SY5Y) compared to human astrocytes (NHA) around 15 and 20 nm surface roughness. In addition, our SCFS measurements revealed a remarkable 2.5-fold increase in adhesion forces (150-164 nN) for SH-SY5Y cells cultured on roughened PI (rPI) surfaces compared to smooth surfaces (60-107 nN). Our data also shows that cells can distinguish changes in nano-roughness as small 2 nm (close to the diameter of a single lipid) and show roughness dependence adhesion while favoring 15 nm. Notably, this enhanced adhesion is accompanied by increased cell elongation upon cell detachment without any significant differences in cell area spreading. The study provides valuable insights into the interplay between nano-topography and cellular responses and offers practical implications for designing biomaterial surfaces with enhanced cellular interactions.

Bioinspired Redwood-Like Scaffolds Coordinated by In Situ-Generated Silica-Containing Hybrid Nanocoatings Promote Angiogenesis and Osteogenesis both In Vitro and In Vivo.

Inspired by natural redwood and bone, a biomimetic strategy is presented to develop a highly bioactive redwood-like nanocomposite via radial freeze casting of biocompatible hydrogels followed by the in situ coprecipitation of a Si-containing CaP hybrid nanocoating (SCPN). The engineered material displays radially aligned macrochannels and a porous network structure similar to those of natural redwood. In addition to acting as a mechanical reinforcement, introducing SCPNs into the weak redwood-like scaffold yields not only a nanoroughened surface topography, a low swelling ratio, retarded enzymatic degradation, and enhanced protein absorption abilities but also the sustained sequential release of Si and Ca ions, thereby providing essential biophysical and biochemical cues for effective bone regeneration. Benefiting from the redwood-like structures and bioactive SCPNs, the biomimetic materials create a favorable microenvironment for promoting the initial adhesion, spreading, proliferation, and migration of bone marrow-derived mesenchymal stem cells and human umbilical vein endothelial cells. Furthermore, the in vitro and in vivo data showed that the biocompatible redwood-like scaffold with precipitated SCPN can synergistically promote osteogenesis and angiogenesis in their aligned direction. Collectively, this work presents a novel bioinspired redwood-like material with multifunctional properties that provides new insight into bone defect repair.

Therapeutic tissue regenerative nanohybrids self-assembled from bioactive inorganic core / chitosan shell nanounits

Natural inorganic/organic nanohybrids are a fascinating model in biomaterials design due to their ultra-microstructure and extraordinary properties. Here, we report unique-structured nanohybrids through self-assembly of biomedical inorganic/organic nanounits, composed of bioactive inorganic nanoparticle core (hydroxyapatite, bioactive glass, or mesoporous silica) and chitosan shell - namely Chit@IOC. The inorganic core thin-shelled with chitosan could constitute as high as 90%, strikingly contrasted with the conventional composites. The Chit@IOC nanohybrids were highly resilient under cyclic load and resisted external stress almost an order of magnitude effectively than the conventional composites. The nanohybrids, with the nano-roughened surface topography, could accelerate the cellular responses through stimulated integrin-mediated focal adhesions. The nanohybrids were also able to load multiple therapeutic molecules in the core and shell compartment and then release sequentially, demonstrating controlled delivery systems. The nanohybrids compartmentally-loaded with therapeutic molecules (dexamethasone, fibroblast growth factor 2, and phenamil) were shown to stimulate the anti-inflammatory, pro-angiogenic and osteogenic events of relevant cells. When implanted in the in vivo calvarium defect model with 3D-printed scaffold forms, the therapeutic nanohybrids were proven to accelerate new bone formation. Overall, the nanohybrids self-assembled from Chit@IOC nanounits, with their unique properties (ultrahigh inorganic content, nano-topography, high resilience, multiple-therapeutics delivery, and cellular activation), can be considered as promising 3D tissue regenerative platforms.

Fabrication of micro–nano-roughened surface with superhydrophobic character on an aluminium alloy surface by a facile chemical etching process

In the present work, we have fabricated a superhydrophobic surface on aluminium alloy 2024 through a simple immersion chemical etching method in hydrochloric acid followed by a functionalization step in stearic acid solution. The impact of etching time on water contact angle was investigated and a contact angle of $$\sim $$ 167 $$^{{\circ }}$$ was reached on the superhydrophobic surface, which was etched for 4 min. Morphology of the surface was evaluated by scanning electron microscopy and the surface chemical analysis was performed by energy-dispersive X-ray spectroscopy and Raman spectroscopy. We show that the fabricated superhydrophobic samples can besides water, also repel other liquids. We also demonstrate the self-cleaning properties of the fabricated samples using graphite particles as contaminants. Ultimately, we assessed the corrosion resistance properties of the fabricated surfaces by the potentiodynamic polarization method. The superhydrophobic surface exhibited increased corrosion potential and polarization resistance along with reduced corrosion current density, all of which are indicative of a significant improvement in corrosion performance of the superhydrophobic surface in comparison with typical aluminium 2024. The cheap and facile superhydrophobic surface fabrication method presented in this study can be applied to large scale samples with no need for electricity or expensive raw materials.

Distinguishment of populated metastatic cancer cells from primary ones based on their invasion to endothelial barrier by biosensor arrays fabricated on nanoroughened poly(methyl methacrylate)

Determining the migratory and invasive capacity of cancer cells as well as clarifying the underlying mechanisms are most relevant for developing biosensors in cancer diagnosis, prognosis, drug development and treatment. Intravasation of metastatic cells into blood stream initiated by their invasion to vascular layer would be a significant characteristic of metastasis. Many types of biochemical and bioelectrical sensors were developed for early detection of metastasis. The simplicity of the setup, the ease of the readout, detection of the trace of rare metastatic cells and the feasibility to perform the assay with standard laboratory equipment are some of the challenges limiting the usability of the sensors in tracing the metastasis. Here we describe a biosensor based on recently reported metastatic diagnosis assay; Metas-Chip, with the assistance of nanoroughened Poly-methyl methacrylate (PMMA) layer to diagnose populated metastatic breast cells from primary cancerous ones. Retraction and detachment of Human Umbilical Vein Endothelial Cells (HUVECs) invaded by metastatic cells as a recently found phenomena is the mechanism of the action. A population of HUVECs would be detached from the gold microelectrodes, patterned on nanoroughened surface, which would lead to large changes in impedance. Here, applying biocompatible and patternable nanoroughened surface instead of using adhesive layers which might produce electrical noises resulted in great sensitivity and detectivity of the sensor. Apart from the tight interaction between endothelial cells and nanocontacts of the electrodes, using low concentration (10%) of tumor cells in this invasion assay, might enhance its application in clinical trials.

Nanotechnology-Based Strategies for Early Cancer Diagnosis Using Circulating Tumor Cells as a Liquid Biopsy.

Circulating tumor cells (CTCs) are cancer cells that shed from a primary tumor and circulate in the bloodstream. As a form of “tumor liquid biopsy”, CTCs provide important information for the mechanistic investigation of cancer metastasis and the measurement of tumor genotype evolution during treatment and disease progression. However, the extremely low abundance of CTCs in the peripheral blood and the heterogeneity of CTCs make their isolation and characterization major technological challenges. Recently, nanotechnologies have been developed for sensitive CTC detection; such technologies will enable better cell and molecular characterization and open up a wide range of clinical applications, including early disease detection and evaluation of treatment response and disease progression. In this review, we summarize the nanotechnology-based strategies for CTC isolation, including representative nanomaterials (such as magnetic nanoparticles, gold nanoparticles, silicon nanopillars, nanowires, nanopillars, carbon nanotubes, dendrimers, quantum dots, and graphene oxide) and microfluidic chip technologies that incorporate nanoroughened surfaces and discuss their key challenges and perspectives in CTC downstream analyses, such as protein expression and genetic mutations that may reflect tumor aggressiveness and patient outcome.

Preparation and characterization of spiral-like micro-struts with nano-roughened surface for enhancing the proliferation and differentiation of preosteoblasts

Factors that are important for the development of tissue-engineered scaffolds include an appropriate selection of the physiochemical structure and surface characteristics to achieve the desired cellular responses depending on the target tissue or organ. In this study, we designed the linear polycaprolactone (PCL) strut, a spiral-like PCL strut that was fabricated using a 3D melt-printing system and a modified spiral-like PCL strut via a 3D melt-printing/plasma-etching process. The surface-roughened spiral-like strut showed significantly enhanced wettability and protein absorption abilities, which were closely related to cellular activities compared to those of linear and spiral-like struts. The in vitro cellular activities using the preosteoblasts (MC3T3-E1) indicated that the newly designed surface-modified spiral-like structure showed significantly higher metabolic activities and mineralization compared to those of conventionally 3D-printed struts.

Nanoscale heterogeniety and workfunction variations in ZnO thin films

Nano-roughened, sol–gel derived polycrystalline ZnO thin films prepared by a thermal ramping procedure were found to exhibit different work function values on a sub-micrometer scale. By Kelvin probe force microscopy (KPFM) two distinct nanoscale regions with work function differing by over 0.1eV were detected which did not coincide with the nano-roughened surface topography. In contrast, a flat ZnO surface displayed a single, uniform distribution. Ultraviolet photoelectron spectroscopy (UPS) studies showed that the average workfunction across a flat ZnO surface was 3.7eV while ZnO with a nano-roughened morphology had a lower workfunction of 3.4eV with indications of electronic heterogeneity across the surface, supporting the KPFM results. Scanning Auger Nanoprobe measurements showed that the chemical composition was uniform across the surface in all samples, suggesting the work function heterogeneity was due to variations in crystallinity or crystal orientation on the surface of these thin films. Such heterogeneity in the electronic properties of materials in thin film devices can significantly influence the interfacial charge transport across materials.

Superhydrophobic Surfaces Boost Fibril Self-Assembly of Amyloid β Peptides.

Amyloid β (Aβ) peptides are the main constituents of Alzheimer's amyloid plaques in the brain. Here we report how the unique microfluidic flows exerted by droplets sitting on superhydrophobic surfaces can influence the aggregation mechanisms of several Aβ fragments by boosting their fibril self-assembly. Aβ(25-35), Aβ(1-40), and Aβ(12-28) were dried both on flat hydrophilic surfaces (contact angle (CA) = 37.3°) and on nanostructured superhydrophobic ones (CA = 175.8°). By embedding nanoroughened surfaces on top of highly X-ray transparent Si3N4 membranes, it was possible to probe the solid residues by raster-scan synchrotron radiation X-ray microdiffraction (μXRD). As compared to residues obtained on flat Si3N4 membranes, a general enhancement of fibrillar material was detected for all Aβ fragments dried on superhydrophobic surfaces, with a particular emphasis on the shorter ones. Indeed, both Aβ(25-35) and Aβ(12-28) showed a marked crystalline cross-β phase with varying fiber textures. The homogeneous evaporation rate provided by these nanostructured supports, and the possibility to use transparent membranes, can open a wide range of in situ X-ray and spectroscopic characterizations of amyloidal peptides involved in neurodegenerative diseases and for the fabrication of amyloid-based nanodevices.

Nanotextured Si Solar Cells on Microtextured Pyramidal Surfaces by Silver-assisted Chemical Etching Process

We investigated nanotextured Si solar cells using the silver-assisted chemical etching process. The nanotexturing process is very sensitive to the concentration of chemical etching solution. The high concentration process results in a nanowire formation for the nanosurfaces and causes severe surface damage to the top region of the micropyramids. These nanowires show excellent light absorption in photoreflectance spectra and radiative light emission in photoluminescence spectra. However, the low concentration process forms a nano-roughened surface and provides high minority carrier lifetimes. The nano-roughened surfaces of the samples show the improved electrical cell properties of quantum efficiency, conversion efficiency, and cell fill factor due to the reduction in the formation of the over-doped dead layer.

Fabrication of nanoporous copper surface by leaching of chill-zone Cu–Zr–Hf alloys

In present work we report the synthesis of nanoporous surface using a copper-based alloy via leaching the less noble element-rich phase out of nanostructured ternary Cu–Hf–Zr alloys. The removal of Hf and Zr by mixed acid etchants in the chill-zone region of rapidly solidified ingots leads to the formation of a nano-roughened surface layer constituted of copper. The average pore and grain size of the obtained structure were shown to be less than 100 nm and 50 nm respectively.

Antireflection coating on silk fabric fabricated from reactive silica nanoparticles and its deepening color performance

In this study, we reported the functionalization of raw silica nanoparticles (SiNPs) with (2-ethyl hydrogen sulfate) sulfonyl (EHSS) groups and their utility as a building block to produce a washing durable antireflection coating on silk fabric. The raw SiNPs were synthesized via classical Stober method and subsequently reacted with (3-methacryloxypropyl) trimethoxysilane, allowing for the raw particle surfaces to be left with ethoxy and methoxy groups. Then, EHSS groups were immobilized onto the SiNP surfaces through the reactions with EHSS group-terminated silane coupling agents. The EHSS functionalization was confirmed by Fourier transform infrared spectroscopy and elemental analysis. These EHSS group-functionalized SiNPs were applied onto silk fabrics by following a dip-coating technique under mild conditions. During this process, the ethoxy and methoxy groups were involved in the condensation reactions to give a cross-linked silica coating that was covalently attached onto the fiber surface through the reactions between EHSS groups and silk fibers. The coating was demonstrated to have a nano-porous microstructure and provided fibers with nano-roughened surfaces, which showed high efficiency in antireflection and increasing light transmission. Since the transmitted light would be selectively absorbed by the dyestuff, the coating applied onto colored silk fabrics gave rise to a more than 30 % increase of the color strength without changing the original hues of the fabrics. Furthermore, being sharply different from the common darkening resins consisting of polysiloxanes and fluorochemicals, the silica coating brought darkening effects without compromising the inherent hydrophilicity of silk fabrics.

Improvement of light extraction efficiency in InGaN/GaN-based light-emitting diodes with a nano-roughened p-GaN surface

The following paper presents a study on the performance of InGaN/GaN-based light-emitting diodes (LEDs) with a nano-roughened p-GaN surface, which were grown by metal-organic chemical vapor deposition. This nano-roughened p-GaN surface was obtained by using nitrogen (N2) as cyclopentadienyl magnesium (Cp2Mg) carrier gas during the growth of p-GaN layer. Research results show that the surface roughness of p-GaN layer is influenced by the injection flow of N2 and the injection time of N2. Under the optimal process condition, the light output power of LED with a nano-roughened p-GaN surface is improved by 30.4 % compared with that of conventional LED with an injection current of 20 mA. Meanwhile, current–voltage curve shows that the electrical performance of this sample is similar to that of conventional LED. The improvement of light output power is mainly attributed to the higher light extraction efficiency when nano-roughened p-GaN surface is adopted.

Emerging Role of Nanomaterials in Circulating Tumor Cell Isolation and Analysis

Circulating tumor cells (CTCs) are low frequency cells found in the bloodstream after having been shed from a primary tumor. These cells are research targets because of the information they may potentially provide about both an individual cancer as well as the mechanisms through which cancer spreads in the process of metastasis. Established technologies exist for CTC isolation, but the recent progress and future of this field lie in nanomaterials. In this review, we provide perspective into historical CTC capture as well as current research being conducted, emphasizing the significance of the materials being used to fabricate these devices. The modern investigation into CTCs initially featured techniques that have since been commercialized. A major innovation in the field was the development of a microfluidic capture device, first fabricated in silicon and followed up with glass and thermopolymer devices. We then specifically highlight the technologies incorporating magnetic nanoparticles, carbon nanotubes, nanowires, nanopillars, nanofibers, and nanoroughened surfaces, graphene oxide and their fabrication methods. The nanoscale provides a new set of tools that has the potential to overcome current limitations associated with CTC capture and analysis. We believe the current trajectory of the field is in the direction of nanomaterials, allowing the improvements necessary to further CTC research.

Final polishing of metals to obtain nanoroughened surface

The concept of the final polishing of hardened steels and nonferrous metals using nanodispersed tribochemically active abrasives based on solid solutions of aluminum and iron oxides is set out in terms of mechanical chemistry. It is demonstrated that the polishing velocity and quality of metals are determined by the formation of an oxide film on their surface and its removal. In order to describe polishing kinetics, the equations for heterogeneous processes are applied. It is shown that the application of these abrasive materials reduces the number of finishing operations with the achievement of a surface roughness no higher than Ra 0.005 μm.

Enhanced performance of silicon quantum dot light-emitting diodes grown on nanoroughened silicon substrate

We report the effect of a nanoroughened Si substrate on silicon quantum dot (Si QD) light-emitting diodes (LEDs). The electroluminescence of Si QD LEDs grown on the nanoroughened Si substrate was remarkably improved by 493% at an injection current of 90 mA compared to those of Si QD LEDs grown on the flat Si substrate. The electrical and optical enhancements were attributed to the enhanced inhomogeneous local electric field on the nanoroughened Si surface and the angular randomization of photons emitted from Si QDs at the nanoroughened surface of silicon nitride layer containing Si QDs.

Improved Light Extraction of GaN-based LEDs with Nano-roughened p-GaN Surfaces

p-GaN surfaces are nano-roughened by plasma etching to improve the optical performance of GaN-based light emitting diodes (LEDs). The nano-roughened GaN present a relaxation of stress. The light extraction of the LEDs with nano-roughened surfaces is greatly improved when compared with that of the conventional LEDs without nano-roughening. PL-mapping intensities of the nano-roughened LED epi-wafers for different roughening times present two to ten orders of enhancement. The light output powers are also higher for the nano-roughened LED devices. This improvement is attributed to that nano-roughened surfaces can provide photons multiple chances to escape from the LED surfaces.

Nano-Processing Techniques Applied in GaN-Based Light-Emitting Devices With Self-Assembly Ni Nano-Masks

We have developed a simple method to fabricate nanoscale masks by using self-assembly Ni clusters formed through a rapid thermal annealing (RTA) process. The density and dimensions of the Ni nano-masks could be precisely controlled. The nano-masks were successfully applied to GaN-based light-emitting diodes (LEDs) with nano-roughened surface, GaN nanorods, and GaN-based nanorod LEDs to enhance light output power or change structure properties. The GaN-based LED with nano-roughened surface by Ni nano-masks and excimer laser etching has increased 55% light output at 20 mA when compared to that without the nano-roughened process. The GaN nanorods fabricated by the Ni nano-masks and ICP-RIE dry etching showed 3.5 times over the as-grown sample in photoluminescence (PL) intensity. The GaN-based nanorod LEDs assisted by photo-enhanced chemical (PEC) wet oxidation process were also demonstrated. The electroluminescence (EL) intensity of the GaN-based nanorod LED with PEC was about 1.76 times that of the as-grown LED. The fabrication, structure properties, physical features, and the optical and electrical properties of the fabricated devices will be discussed.

Improvement of light output in GaN-based power chip light-emitting diodes with a nano-rough surface by nanoimprint lithography

The enhancement of light extraction of gallium nitride (GaN)-based power chip (PC) light-emitting diodes (LEDs) with a p-GaN rough surface by nanoimprint lithography (NIL) is presented. At a driving current of 350 mA and a chip size of 1 mm × 1 mm, the light output power of the PC LEDs with a p-GaN rough surface (etching depth from 130 to 150 nm) showed an enhancement of 24% on wafer when compared with the same device without NIL. Current–voltage results indicated an ohmic contact by the increase in the contact area of the nano-roughened surface at 200 mA. This paper offers a promising potential for enhancing the output powers of commercial LEDs.

Nano-roughening n-side surface of AlGaInP-based LEDs for increasing extraction efficiency

A chemical wet etching technique is presented to form a nano-roughened surface with triangle-like morphology on n-side-up AlGaInP-based LEDs fabricated by adopting adhesive layer bonding scheme. A simple and commonly used H 3PO 4-based solution was applied for chemical wet etching. The morphology of nano-roughened surfaces is analyzed by the atomic force microscope (AFM) and significantly related to the enhancement factor of the LED output power. The output power shows 80% increase after optimizing the nano-roughened morphology of n-side surface, as compared to the ordinary flat surface LED.