Estimation of the Depletion Layer Thickness in Silicon Nanowire-Based Biosensors from Attomolar-Level Biomolecular Detection.

Silicon nanowire (SiNW) biosensors have attracted a lot of attention due to their superior sensitivity. Recently, the dependence of biomolecule detection sensitivity on the nanowire (NW) width, number, and doping density has been partially investigated. However, the primary reason for achieving ultrahigh sensitivity has not been elucidated thus far. In this study, we designed and fabricated SiNW biosensors with different widths (10.8-155 nm) by integrating a complementary metal-oxide-semiconductor process and electron beam lithography. We aimed to investigate the detection limit of SiNW biosensors and reveal the critical effect of the 10-nm-scaled SiNW width on the detection sensitivity. The sensing performance was evaluated by detecting antiovalbumin immunoglobulin G (IgG) with various concentrations (from 6 aM to 600 nM). The initial thickness of the depletion region of the SiNW and the changes in the depletion region due to biomolecule binding were calculated. The basis of this calculation are the resistance change ratios as functions of IgG concentrations using SiNWs with different widths. The calculation results reveal that the proportion of the depletion region over the entire SiNW channel is the essential reason for high-sensitivity detection. Therefore, this study is crucial for an indepth understanding on how to maximize the sensitivity of SiNW biosensors.

Wafer-Scale LSPR Substrate: Oblique Deposition of Gold on a Patterned Sapphire Substrate.

Label-free detection of biomolecules using localized surface plasmon resonance (LSPR) substrates is a highly attractive method for point-of-care (POC) testing. One of the remaining challenges to developing LSPR-based POC devices is to fabricate the LSPR substrates with large-scale, reproducible, and high-throughput. Herein, a fabrication strategy for wafer-scale LSPR substrates is demonstrated using reproducible, high-throughput techniques, such as nanoimprint lithography, wet-etching, and thin film deposition. A transparent sapphire wafer, on which SiO2-nanodot hard masks were formed via nanoimprint lithography, was anisotropically etched by a mixed solution of H2SO4 and H3PO4, resulting in a patterned sapphire substrate (PSS). An LSPR substrate was finally fabricated by oblique deposition of Au onto the PSS, which was then applied to label-free detection of the binding events of biomolecules. To the best of our knowledge, this paper is the first report on the application of the PSS used as an LSPR template by obliquely depositing a metal.

Photothermally Enhanced Molecular Delivery and Cellular Positioning on Patterned Plasmonic Interfaces.

Photothermal conversion effect of plasmonic nanostructures is considered as a promising technique for cellular and molecular manipulations owing to controllability of local temperature. Therefore, this technique has been extensively applied to biological studies such as controlling cellular behavior, delivery of biologics, and biomolecular detection. Herein, we propose a novel method for directed cell positioning and photothermally modulated molecular delivery to the cells using patterned plasmonic interfaces. Plasmonic substrates with gold nanorods (GNRs) and cell adhesion molecules fabricated by microcontact printing are optimized for cellular positioning on designated patterns. Through the photothermal conversion effect of GNRs on the pattern, we further demonstrate on-demand, light-induced delivery of drug molecules to the target cells. We expect that this approach will provide a new way to study single cellular behaviors and enhance molecular delivery to the target cells.

Electrochemical determination of antihypertensive drugs by employing costless and portable unmodified screen-printed electrodes.

Hypertension increases the risk of heart disease and stroke, is commonly known as a silent killer disease and considered as one of the key risk factor for premature death and disability over the world. Herein, we report for the first time a sensitive, costless and reproducible voltammetric method for individual determination of five antihypertensive drugs namely, propranolol (PRO), timolol (TIM), amlodipine (AML), amiloride (AMI) and triamterene (TRI) using differential pulse voltammetry at bare/unmodified screen-printed carbon electrodes (SPEs) in presence of sodium dodecyl sulfate (SDS). Each drug exhibits an electrochemical signal in aqueous media which is significantly enhanced in presence of optimized concentration of SDS due to accumulation of the protonated drug molecules and electrostatically interaction with negatively charged micellar structures. As a result, the spherical micellar orientation of SDS onto the graphitic surface of SPEs offered the analytically sensitive determination of the target drugs over a wide linear concentration range with nano-molar detection limits possible negating the need for any complicated surface modifications. Finally, the proposed voltammetric method was successfully utilized in the individual determination of the target antihypertensive drugs in pharmaceutical formulations and human urine samples.

High-resolution Patterning Using Two Modes of Electrohydrodynamic Jet: Drop on Demand and Near-field Electrospinning.

Electrohydrodynamic (EHD) jet printing has drawn attention in various fields because it can be used as a high-resolution and low-cost direct patterning tool. EHD printing uses a fluidic supplier to maintain the extruded meniscus by pushing the ink out of the nozzle tip. The electric field is then used to pull the meniscus down to the substrate to produce high-resolution patterns. Two modes of EHD printing have been used for fine patterning: continuous near-field electrospinning (NFES) and dot-based drop-on-demand (DOD) EHD printing. According to the printing modes, the requirements for the printing equipment and ink viscosity will differ. Even though two different modes can be implemented with a single EHD printer, the realization methods significantly differ in terms of ink, fluidic system, and driving voltage. Consequently, without a proper understanding of the jetting requirements and limitations, it is difficult to obtain the desired results. The purpose of this paper is to present a guideline so that inexperienced researchers can reduce the trial and error efforts to use the EHD jet for their specific research and development purposes. To demonstrate the fine-patterning implementation, we use Ag nanoparticle ink for the conductive patterning in the protocol. In addition, we also present the generalized printing guidelines that can be used for other types of ink for various fine-patterning applications.

Inkjet printing-based ß-secretase fluorescence resonance energy transfer (FRET) assay for screening of potential ß-secretase inhibitors of Alzheimer's disease.

Amyloid-ß (Aß) is generated by proteolytic processing of amyloid precursor protein (APP) by beta-secretase (BACE-1) and gamma-secretase. Amyloid-ß is responsible for the formation of senile plaques in Alzheimer's disease (AD). Consequently, inhibition of ß-secretase (BACE-1), a rate-limiting enzyme in the production of Aß, constitutes an attractive therapeutic approach to the treatment of AD. This paper reports an inkjet printing-based fluorescence assay for high throughput screening of ß-secretase inhibitors achieved by employing a BACE-1 FRET substrate (Rh-Glu-Val-Asn-Leu-Asp-Ala-Glu-Phe-Lys-Quencher). This peptide substrate is known to be a readily available and suitable substrate for proteolytic activity, and it has high affinity to BACE-1. The BACE-1 peptide substrate printed on parchment paper was effectively cleaved by BACE-1, which was printed on the same spot. The amount of enzyme and substrate required for this inkjet printing-based BACE-1 assay can be less than 1.4ⅹ103, permitting the evaluation of inhibitor activity with femtomolar potency. The inkjet-printing-based BACE-1 inhibitory assay revealed inhibitory effects of inhibitor IV and STA on BACE-1 with an IM50 of 1.00 × 10-15 mol and 1.01 × 10-14 mol, respectively. These data confirm that both BACE-1 inhibitors (inhibitor IV and STA) actively inhibited the BACE-1 proteolysis of BACE-1 substrate on parchment paper. It important to note that the number of mole of BACE-1-substrate and enzyme utilized in the printing-based enzymatic assay are 1.4ⅹ103 smaller than the amount used in the conventional well-plate assay. The inkjet printing-based inhibitory assay constitutes a versatile high throughput technique and the IM50 values of the inhibitors were obtained with satisfactory reproducibility, suggesting that this inkjet-printing BACE-1 inhibitory assay could be quite suitable for the screening of new potential BACE-1 inhibitors for AD.

The examination of vegetable- and mineral oil-based inks' effects on print quality: Green printing effects with different oils.

INTRODUCTION: Printing inks oil selection is related to the desired nature of the varnish in the ink production. Petroleum-derived mineral oils and vegetable oils can be used in offset inks. METHODS: In this study, the behaviors of vegetable- and mineral oil-based inks on uncoated and coated paper surfaces were investigated in terms of printability. Solid tone test prints were done with offset printing of these inks. Print gloss of the printed samples was measured and a light fastness test was implemented on these samples in order to determine the resistance to fading. Absorption behavior and contact angles of the ink-printed films on the test papers were measured with the sessile water drop method depending on time, and surface energies were calculated. RESULTS: On both paper types, linseed-soybean oil-based vegetable ink gave the highest brightness value. The lowest print gloss results on the paper were obtained from soybean oil-based inks. The lowest color change was recorded with mineral oil-based inks on gloss-coated papers. According to the ink-film-surface relation, when the contact angle is high, surface energy decreases and the absorbency of the ink-film is lower. CONCLUSIONS: In this study, the behaviors of vegetable- and mineral oil-based inks on different paper surfaces, and the effect on the quality of printability as well as differences, have been evaluated, taking environmental and health factors into consideration.

A printable hydrogel microarray for drug screening avoids false positives associated with promiscuous aggregating inhibitors.

A significant problem in high-throughput drug screening is the disproportionate number of false hits associated with drug candidates that form colloidal aggregates. Such molecules, referred to as promiscuous inhibitors, nonspecifically inhibit multiple enzymes and are thus not useful as potential drugs. Here, we report a printable hydrogel-based drug-screening platform capable of non-ambiguously differentiating true enzyme inhibitors from promiscuous aggregating inhibitors, critical for accelerating the drug discovery process. The printed hydrogels can both immobilize as well as support the activity of entrapped enzymes against drying or treatment with a protease or chemical denaturant. Furthermore, the printed hydrogel can be applied in a high-throughput microarray-based screening platform (consistent with current practice) to rapidly ( <25 min) and inexpensively identify only clinically promising lead compounds with true inhibitory potential as well as to accurately quantify the dose-response relationships of those inhibitors, all while using 95% less sample than required for a solution assay.

Innovative Cryopreservation Process Using a Modified Core/Shell Cell-Printing with a Microfluidic System for Cell-Laden Scaffolds.

This work investigated the printability and applicability of a core/shell cell-printed scaffold for medium-term (for up to 20 days) cryopreservation and subsequent cultivation with acceptable cellular activities including cell viability. We developed an innovative cell-printing process supplemented with a microfluidic channel, a core/shell nozzle, and a low-temperature working stage to obtain a cell-laden 3D porous collagen scaffold for cryopreservation. The 3D porous biomedical scaffold consisted of core/shell struts with a cell-laden collagen-based bioink/dimethyl sulfoxide mixture in the core region and an alginate/poly(ethylene oxide) mixture in the shell region. Following 2 weeks of cryopreservation, the cells (osteoblast-like cells or human adipose stem cells) in the scaffold showed good viability (over 90%), steady growth, and mineralization similar to those of a control scaffold fabricated using a conventional cell-printing process without cryopreservation. We believe that these results are attributable to the optimized fabrication processes the cells underwent, including safe freezing/thawing processes. On the basis of these results, this fabrication process has great potential for obtaining core/shell cell-laden collagen scaffolds for cryopreservation, which have various tissue engineering applications.

Low-cost and disposable sensors for the simultaneous determination of coenzyme Q10 and α-lipoic acid using manganese (IV) oxide-modified screen-printed graphene electrodes.

In this work, for the first time, manganese (IV) oxide-modified screen-printed graphene electrodes (MnO2/SPGEs) were developed for the simultaneous electrochemical detection of coenzyme Q10 (CoQ10) and α-lipoic acid (ALA). This sensor exhibits attractive benefits such as simplicity, low production costs, and disposability. Cyclic voltammetry (CV) was used to characterize the electrochemical behavior of the analyte and investigate the capacitance and electroactive surface area of the unmodified and modified electrode surfaces. The electrochemical behavior of CoQ10 and ALA on MnO2/SPGEs was also discussed. Additionally, square wave anodic stripping voltammetry (SWASV) was used for the quantitative determination of CoQ10 and ALA. Under optimal conditions, the obtained signals are linear in the concentration range from 2.0 to 75.0 µg mL-1 for CoQ10 and 0.3-25.0 µg mL-1 for ALA. The low limits of detection (LODs) were found to be 0.56 µg mL-1 and 0.088 µg mL-1 for CoQ10 and ALA, respectively. Moreover, we demonstrated the utility and applicability of the MnO2/SPGE sensor through simultaneous measurements of CoQ10 and ALA in dietary supplements. The sensor provides high accuracy measurements, exhibiting its high potential for practical applications.

Printable organometallic perovskite enables large-area, low-dose X-ray imaging.

Medical X-ray imaging procedures require digital flat detectors operating at low doses to reduce radiation health risks. Solution-processed organic-inorganic hybrid perovskites have characteristics that make them good candidates for the photoconductive layer of such sensitive detectors. However, such detectors have not yet been built on thin-film transistor arrays because it has been difficult to prepare thick perovskite films (more than a few hundred micrometres) over large areas (a detector is typically 50 centimetres by 50 centimetres). We report here an all-solution-based (in contrast to conventional vacuum processing) synthetic route to producing printable polycrystalline perovskites with sharply faceted large grains having morphologies and optoelectronic properties comparable to those of single crystals. High sensitivities of up to 11 microcoulombs per air KERMA of milligray per square centimetre (µC mGyair-1 cm-2) are achieved under irradiation with a 100-kilovolt bremsstrahlung source, which are at least one order of magnitude higher than the sensitivities achieved with currently used amorphous selenium or thallium-doped cesium iodide detectors. We demonstrate X-ray imaging in a conventional thin-film transistor substrate by embedding an 830-micrometre-thick perovskite film and an additional two interlayers of polymer/perovskite composites to provide conformal interfaces between perovskite films and electrodes that control dark currents and temporal charge carrier transportation. Such an all-solution-based perovskite detector could enable low-dose X-ray imaging, and could also be used in photoconductive devices for radiation imaging, sensing and energy harvesting.

Printing of small molecular medicines from the vapor phase.

There is growing need to develop efficient methods for early-stage drug discovery, continuous manufacturing of drug delivery vehicles, and ultra-precise dosing of high potency drugs. Here we demonstrate the use of solvent-free organic vapor jet printing to deposit nanostructured films of small molecular pharmaceutical ingredients, including caffeine, paracetamol, ibuprofen, tamoxifen, BAY 11-7082 and fluorescein, with accuracy on the scale of micrograms per square centimeter, onto glass, Tegaderm, Listerine tabs, and stainless steel microneedles. The printed films exhibit similar crystallographic order and chemistry as the original powders; controlled, order-of-magnitude enhancements of dissolution rate are observed relative to powder-form particles. In vitro treatment of breast and ovarian cancer cell cultures in aqueous media by tamoxifen and BAY 11-7082 films shows similar behavior to drugs pre-dissolved in dimethyl sulfoxide. The demonstrated precise printing of medicines as films, without the use of solvents, can accelerate drug screening and enable continuous manufacturing, while enhancing dosage accuracy.Traditional approaches used in the pharmaceutical industry are not precise or versatile enough for customized medicine formulation and manufacture. Here the authors produce a method to form coatings, with accurate dosages, as well as a means of closely controlling dissolution kinetics.

Multicomponent High-throughput Drug Screening via Inkjet Printing to Verify the Effect of Immunosuppressive Drugs on Immune T Lymphocytes.

High-throughput drug screening based on a multi-component array can be used to identify a variety of interaction between cells and drugs for suitable purposes. The signaling of immune cells is affected by specific proteins, diverse drug combinations, and certain immunosuppressive drugs. The effect of a drug on an organism is usually complex and involves interactions at multiple levels. Herein, we developed a multilayer fabricating system through the high-throughput assembly of nanofilms with inkjet printing to investigate the effects of immunosuppressive drugs. Immunosuppressive drugs or agents occasionally cause side effects depending on drug combinations or a patient's condition. By incorporating various drug combinations for understanding interaction between drugs and immune cells, we were able to develop an immunological drug screening kit with immunosuppressive drugs. Moreover, the ability to control the combination of drugs, as well as their potential for high-throughput preparation should be of great benefit to the biomedical and bioanalytical field.

Inkjet printed periodical micropatterns made of inert alumina ceramics induce contact guidance and stimulate osteogenic differentiation of mesenchymal stromal cells.

Bioinert high performance ceramics exhibit detrimental features for implant components with direct bone contact because of their low osseointegrating capability. We hypothesized that periodical microstructures made of inert alumina ceramics can influence the osteogenic differentiation of human mesenchymal stromal cells (hMSC). In this study, we manufactured pillared arrays made of alumina ceramics with periodicities as low as 100µm and pillar heights of 40µm employing direct inkjet printing (DIP) technique. The response of hMSC to the microstructured surfaces was monitored by measuring cell morphology, viability and formation of focal adhesion complexes. Osteogenic differentiation of hMSCs was investigated by alkaline phosphatase activity, mineralization assays and expression analysis of respective markers. We demonstrated that MSCs react to the pillars with contact guidance. Subsequently, cells grow onto and form connections between the microstructures, and at the same time are directly attached to the pillars as shown by focal adhesion stainings. Cells build up tissue-like constructs with heights up to the micropillars resulting in increased cell viability and osteogenic differentiating properties. We conclude that periodical micropatterns on the micrometer scale made of inert alumina ceramics can mediate focal adhesion dependent cell adhesion and stimulate osteogenic differentiation of hMSCs.

Encapsulated Hydrogels by E-beam Lithography and Their Use in Enzyme Cascade Reactions.

Electron beam (e-beam) lithography was employed to prepare one protein immobilized hydrogel encapsulated inside another by first fabricating protein-reactive hydrogels of orthogonal reactivity and subsequently conjugating the biomolecules. Exposure of thin films of eight arm star poly(ethylene glycol) (PEG) functionalized with biotin (Biotin-PEG), alkyne (Alkyne-PEG) or aminooxy (AO-PEG) end-groups to e-beam radiation resulted in cross-linked hydrogels with the respective functionality. It was determined via confocal microscopy that a nominal size exclusion effect exists for streptavidin immobilized on Biotin-PEG hydrogels of feature sizes ranging from 5 to 40 µm. AO-PEG was subsequently patterned as an encapsulated core inside a contiguous outer shell of Biotin-PEG. Similarly, Alkyne-PEG was patterned as a core inside an AO-PEG shell. The hydrogel reactive end-groups were conjugated to dyes or proteins of complementary reactivity, and the three-dimensional (3-D) spatial orientation was determined for both configurations using confocal microscopy. The enzyme glucose oxidase (GOX) was immobilized in the core of the encapsulated Alkyne-PEG core/ AO-PEG shell architecture, and horseradish peroxidase (HRP) was conjugated to the shell periphery. Bioactivity for the HRP-GOX enzyme pair was observed in this encapsulated configuration by demonstrating that the enzyme pair was capable of enzyme cascade reactions.

[Preliminary exploration on the relationship between hand-copied edition and block-printed edition of Fu ke cai zhen (Collected Essentials of Women Disease)].

There are two extant versions of Fu ke cai zhen (Collected Essentials of Women Disease) nowadays, namely, Yang Jichun's hand-copied version, and block-printed version of Direntang Sanctum. The former one was formally sorted out by Prof. Wang Yaoting of the Changchun College of TCM and published in 1988 in the Jilin Journal of TCM in serial form. Though Yang's version was completed later than the block-printed one, however, it can be found by careful comparison that it was not copied after the block-printed edition, but probably written from the draft of the author himself.

Ultra-high performance liquid chromatographic determination of antioxidants in teas using inkjet-printed graphene-polyaniline electrode.

A development of ultra-high performance liquid chromatographic coupled with a novel inkjet-printed conductive ink-modified electrode for a fast and simultaneous determination of polyphenolic antioxidants was achieved. Two printing techniques were selected for fabrication and modification including (i) an in-house screen-printing method and (ii) an inkjet-printing method, respectively. A conductive ink containing graphene and polyaniline nanocomposite (G-PANI) was precisely casted onto the surface of screen-printed carbon electrode (SPCE) using a dimatix inkjet material printer. Compared to a bare SPCE, the G-PANI-modified screen-printed carbon electrode (G-PANI/SPCE) exhibited higher electrochemical sensitivity with increase (2-4 times) of peak current of each antioxidant. Moreover, four antioxidants were successfully separated and determined within 3 min using a reverse phase ultra-high performance liquid chromatography (UHPLC) with a mobile phase containing phosphate buffer and acetonitrile (90:10 v/v). Under an optimal detection potential at +1.2V vs. Ag/AgCl, linear calibrations and limits of detection (S/N=3) for antioxidants were found to be 0.01-10 µg mL(-1) and 1.38-1.94 ng mL(-1), respectively. Finally, this proposed method has been successfully used for the determination of antioxidants in tea samples, the results obtained from our presented method were within a highly good agreement those obtained from a standard UHPLC-UV method.

Microfluidic-Enabled Print-to-Screen Platform for High-Throughput Screening of Combinatorial Chemotherapy.

Since the 1960s, combination chemotherapy has been widely utilized as a standard method to treat cancer. However, because of the potentially enormous number of drug candidates and combinations, conventional identification methods of the effective drug combinations are usually associated with significantly high operational costs, low throughput screening, laborious and time-consuming procedures, and ethical concerns. In this paper, we present a low-cost, high-efficiency microfluidic print-to-screen (P2S) platform, which integrates combinatorial screening with biomolecular printing for high-throughput screening of anticancer drug combinations. This P2S platform provides several distinct advantages and features, including automatic combinatorial printing, high-throughput parallel drug screening, modular disposable cartridge, and biocompatibility, which can potentially speed up the entire discovery cycle of potent drug combinations. Microfluidic impact printing utilizing plug-and-play microfluidic cartridges is experimentally characterized with controllable droplet volume and accurate positioning. Furthermore, the combinatorial print-to-screen assay is demonstrated in a proof-of-concept biological experiment which can identify the positive hits among the entire drug combination library in a parallel and rapid manner. Overall, this microfluidic print-to-screen platform offers a simple, low-cost, high-efficiency solution for high-throughput large-scale combinatorial screening and can be applicable for various emerging applications in drug cocktail discovery.

[Textual research on the engraved editions of Nei wai yan fang mi chuan (Secret Teaching of Proved Prescriptions for Internal and External Diseases)].

Zhao Lian's book Nei wai yan fang mi chuan (Secret Teaching of Proved Prescriptions for Internal and External Diseases) was firstly engraved in the 21st year of Guangxu reign of the Qing dynasty. There are altogether four different engraved editions separately collected in the Library of Academy of Medical Sciences, Library of Zhenjiang City, Library of Changchun University of TCM, and Library of Shanghai University of TCM, printed in different times with different sizes of its contents. It is better to call all these editions the engraved versions of Guangxu reign. All of them are engraved and printed after the mother edition with some blocks hollowed-out and supplemented. Hence, the title "engraved edition of Yiyou or the 11th year of Guangxu reign (1885) of the Qing dynasty" carried in The General Catalogue of Ancient Books of TCM is wrong.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer.

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.