Nanoengineered phosphorus doped graphitic carbon nitride based ultrasensitive biosensing platform for Swine flu detection

In the present study, we developed an amino-polyindole modified phosphorus doped graphitic carbon nitride nanomaterial (APIN/P-g-C3N4) based immunosensing biochip for Serum amyloid A (SAA) biomarker towards early diagnosis of Swine flu. The P-g-C3N4 was synthesis via polycondensation and functionalized with APIN. Further, the biochip was fabricated by modifying the working area of SPE with APIN/P-g-C3N4 using drop cast method, APIN introduced the larger loading of -NH2 group moieties onto P-g-C3N4 matrix and benefitted to reinforced the biomolecules via covalent linkages. The monoclonal anti-SAA was conjugated onto APIN/P-g-C3N4/SPE using EDC-NHS chemistry and BSA was added for non-specific site blocking. The structural, chemical, composition and morphological characteristics of the synthesized, functionalized nanomaterial and fabricated biochips were investigated by XRD, XPS, FT-IR spectroscopy, SEM, FE-SEM and TEM techniques. Further, the electrochemical characterization and response studies of fabricated biochip were analyzed using the CV and DPV techniques. Based on the analytical performance of the proposed immunosensing biochip i.e. BSA/anti-SAA/APIN/P-g-C3N4/SPE, it is capable to detect SAA protein with ultra sensitivity of 79.5 μA log (mL ng-1) cm-2, ultralow limit of detection of 5 ng mL-1 and wider linear detection range of 5 ng mL-1-500 μg mL-1 with quick response time of 10 min. Moreover, the fabricated immunosensing biochips was used to analyse SAA protein in spiked serum samples and the achieved results demonstrated the good agreement with the electrochemical response observed in standard SAA protein samples in analytical solution. The proposed biochip can provide insights for developing a wide range of clinical screening tools for detecting various contagious diseases.

Discovery of anti-allergic components in Guomingkang Formula using sensitive HEMT biochips coupled with in vitro and in vivo validation

BACKGROUND

Allergic rhinitis (AR) is a prevalent allergic disease, which seriously affects the sufferers' life quality and increases the socioeconomic burden. Guominkang (GMK), a well-known prescription for AR treatment, showed satisfactory effects; while its anti-allergic components remain to be disclosed. AlGaN/GaN HEMT biochip is more sensitive and cost-effective than other binding equipments, indicating its great potential for screening of active ingredients from herbal medicines.

METHODS

AR mouse models were first established to test the anti-allergic effect of GMK and discover the ingredients absorbed into blood by ultra-high performance liquid chromatography-mass spectra (UHPLC-MS). Then, novel Syk/Lyn/Fyn-functionalized high electron mobility transistor (HEMT) biochips with high sensitivity and specificity were constructed and applied to screen the active components. Finally, the results from HEMT biochips screening were validated via in silico (molecular docking and molecular dynamics simulation), in vitro (RBL-2H3 cells), and in vivo (PCA mice model) assays.

RESULTS

GMK showed a potent therapeutic effect on AR mice, and fifteen components were identified from the medicated plasma. Furthermore, hamaudol was firstly found to selectively inhibit the Syk and Lyn, and emodin was to selectively inhibit Lyn, which were further confirmed by isothermal titration calorimetry, molecular docking, and molecular dynamics simulation analyses. Suppression of the activation of FcεRI-MAPK signals might be the possible mechanism of the anti-allergic effect of hamaudol.

CONCLUSIONS

The targets of emodin and hamaudol were discovered by HEMT biochips for the first time. This study provided a novel and effective strategy to discover active components in a complex herbal formula by using AlGaN/GaN HEMT biochips.

Cytosolic Calcium Measurement Utilizing a Single-Cell Biochip to Study the Effect of Curcumin and Resveratrol on a Single Glioma Cell

A microfluidic method has been developed for real-time measurement of the effects of curcumin on the intracellular calcium concentration in a single glioma cell (U87-MG). This method is based on quantitative fluorescence measurement of intracellular calcium in a cell selected in a single-cell biochip. This biochip consists of three reservoirs, three channels, and a V-shaped cell retention structure. Because of the adherent nature of glioma cells, a single cell can adhere within the aforementioned V-shaped structure. The single-cell calcium measurement will minimize cell damage caused by conventional cell calcium assay methods. Previous studies have shown that curcumin increased cytosolic calcium in glioma cells using the fluorescent dye: Fluo-4. So in this study, the effects of 5 μM and 10 μM solutions of curcumin on the increases of cytosolic calcium in a single glioma cell have been measured. Moreover, the effects of 100 μM and 200 μM of resveratrol are measured. At the final stage of the experiments, ionomycin was used to increase the intracellular calcium to the highest possible level due to dye saturation. It has been demonstrated that microfluidic cell calcium measurement is a real-time cytosolic assay that requires small quantities of reagent, which will have potential uses for drug discovery.

Simultaneous Screening of Six Families of Antibiotic Residues in Milk Samples by Biochip Multi-array Technology

Background

Antimicrobial compounds are used in animal husbandry to prevent and treat bacterial diseases and as illegal growth-promoting agents. Due to the excessive and inappropriate use of antibiotics, the antibiotic residues in milk can cause allergic reactions and antibiotic resistance. A rapid biochip-based method for the multi-analyte screening of 6 families of antibiotic residues (quinolones, ceftiofur, florfenicol, streptomycin, tylosin, and tetracyclines) in milk was validated based on Commission Decision 2002/657 and the European guidance for screening methods for veterinary medicinal products.

Methods

This methodology allows the 6 antibiotic families to be detected simultaneously, increasing the screening capacity and reducing costs in test settings. The method's applicability was shown by screening 38 UHT cow milk samples taken from Tehran province, IR Iran.

Results

The results showed that the positive threshold T was above Fm, and the CCβ was below the European Commission's Maximum Residue Limit (MRL) (100 ppb for ceftiofur and tetracycline and 50 ppb for tylosin in milk). Norfloxacin was detected in about 8% of the samples and tylosin in 2.63%. The total antibiotic concentration in UHT cow milk samples was lower than the European Commission's MRL.

Conclusions

This study showed that the biochip technique is valid for screening tylosin, ceftiofur, streptomycin, tetracycline, norfloxacin, and florfenicol in milk. It was found that the method was easy, quick, and capable of detecting 6 families of antibiotic residues simultaneously from a single milk sample without sample preparation.

Assaying Proliferation Characteristics of Cells Cultured Under Static Versus Periodic Conditions

Two-dimensional in vitro culture models are widely being employed for assessing a vast variety of biological questions in different scientific fields. Common in vitro culture models are typically maintained under static conditions, where the surrounding culture medium is replaced every few days-typically every 48 to 72 h-with the aim to remove metabolites and to replenish nutrients. Although this approach is sufficient for supporting cellular survival and proliferation, static culture conditions do mostly not reflect the in vivo situation where cells are continuously being perfused by extracellular fluid, and thus, create a less-physiological environment. In order to evaluate whether the proliferation characteristics of cells in 2D culture maintained under static conditions differ from cells kept in a dynamic environment, in this chapter, we provide a protocol for differential analysis of cellular growth under static versus pulsed-perfused conditions, mimicking continuous replacement of extracellular fluid in the physiological environment. The protocol involves long-term life-cell high-content time-lapse imaging of fluorescent cells at 37 °C and ambient CO₂ concentration using multi-parametric biochips applicable for microphysiological analysis of cellular vitality. We provide instructions and useful information for (i) the culturing of cells in biochips, (ii) setup of cell-laden biochips for culturing cells under static and pulsed-perfused conditions, (iii) long-term life-cell high-content time-lapse imaging of fluorescent cells in biochips, and (iv) quantification of cellular proliferation from image series generated from imaging of differentially cultured cells.

Self-assembly strategy to reduce non-specific adsorption for the development of high sensitivity quantitative immunoassay

The development of functionalized surfaces with low non-specific adsorption is important for their biomedical applications. To inhibit non-specific adsorption on glass substrate, we designed a novel optical biochip by modifying a layer of dense negatively charged film (SO₃^2-) on its substrate surface via self-assembly. Compared with the untreated glass substrate, it reduced the adsorption by about 300-fold or 400-fold by poly (styrene sulfonic acid) sodium salt (PSS), or meso-tetra (4-sulfonatophenyl) porphine dihydrochloride (TSPP) on individually the modified glass substrate. Considering the effect of fluorescence resonance energy transfer (FRET) between TSPP and the QDs in solution by mixing, a strategy of 2-layer of TSPP followed by 4-layer of PSS was designed to modify the glass for preparing biochips. Under the optimized conditions, the biochip on functionalized glass substrate co-treated with TSPP and PSS realized the sensitive quantitative detection of C-reactive protein (CRP) based on a quantum dot fluorescence immunosorbent assay (QD-FLISA). The limit of detection (LOD) for CRP achieved 0.69 ng/mL with the range of 1-1,000 ng/mL using TSPP and PSS co-treated glass substrate surface, which was respectively about 1.9-fold and 7.5-fold more sensitive to the PSS-modified biochip and the TSPP-modified biochip. This work demonstrated an effective and convenient strategy to obtain biochips with low non-specific adsorption properties on functionalized surfaces, thus providing a new approach for creating ultra-high sensitivity microchannels or microarrays on glass substrates.

A magneto-optical biochip for rapid assay based on the Cotton-Mouton effect of γ-Fe2O3@Au core/shell nanoparticles

Background

In the past decades, different diseases and viruses, such as Ebola, MERS and COVID-19, impacted the human society and caused huge cost in different fields. With the increasing threat from the new or unknown diseases, the demand of rapid and sensitive assay method is more and more urgent.

Results

In this work, we developed a magneto-optical biochip based on the Cotton–Mouton effect of γ-Fe₂O₃@Au core/shell magnetic nanoparticles. We performed a proof-of-concept experiment for the detection of the spike glycoprotein S of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The assay was achieved by measuring the magneto-optical Cotton–Mouton effect of the biochip. This magneto-optical biochip can not only be used to detect SARS-CoV-2 but also can be easily modified for other diseases assay.

Conclusion

The assay process is simple and the whole testing time takes only 50 min including 3 min for the CM rotation measurement. The detection limit of our method for the spike glycoprotein S of SARS-CoV-2 is estimated as low as 0.27 ng/mL (3.4 pM).

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01030-z.

We developed a biochip for rapid assay based on the magneto-optical Cotton–Mouton (CM) effect of γ-Fe₂O₃@Au core/shell magnetic nanoparticles.

The easy and quick assay for detection of the spike glycoprotein S of SARS-CoV-2 was demonstrated, and whole process takes approximately 50 min including 3 min for the CM rotation measurement with the detection limit of 0.27 ng/mL (3.4 pM).

This magneto-optical biochip we proposed can be easily modified to use as assays for other diseases.

Xenopus chip for single-egg trapping, in vitro fertilization, development, and tadpole escape

Xenopus laevis is highly suitable as a toxicology animal model owing to its advantages in embryogenesis research. For toxicological studies, a large number of embryos must be handled simultaneously because they very rapidly develop into the target stages within a short period of time. To efficiently handle the embryos, a convenient embryo housing device is essential for fast and reliable assessment and statistical evaluation of malformation caused by toxicants. Here, we suggest 3D fabrication of single-egg trapping devices in which Xenopus eggs are fertilized in vitro, and the embryos are cultured. We used manual pipetting to insert the Xenopus eggs inside the trapping sites of the chip. By introducing a liquid circulating system, we connected a sperm-mixed solution with the chip to induce in vitro fertilization of the eggs. After the eggs were fertilized, we observed embryo development involving the formation of egg cleavage, blastula, gastrula, and tadpole. After the tadpoles grew inside the chip, we saved their lives by enabling their escape from the chip through reverse flow of the culture medium. The Xenopus chip can serve as an incubator to induce fertilization and monitor normal and abnormal development of the Xenopus from egg to tadpole.

A wideband picosecond pulsed electric fields (psPEF) exposure system for the nanoporation of biological cells

The effects and mechanisms of ultrashort and intense pulsed electric fields on biological cells remain some unknown. Especially for picosecond pulsed electric fields (psPEF) with a high pulse repetition rate, electroporation or nanoporation effects could be induced on cell membranes and intracellular organelle membranes. In this work, the design, implementation, and experimental validation of a wideband psPEF exposure system (WPES) is reported, comprising picosecond pulser and wideband biochip, for the in vitro exposure of suspended cells to high-intensity psPEF. Excited by repetitive picosecond pulses (the duration of 200 ps and the amplitude of a few kilovolts), the proposed biochip adopts grounded coplanar waveguide (GCPW) for a wide working bandwidth, which was fabricated with 160 μm thick electrodes for uniform distribution of psPEF in the cross-section. To ensure that only psPEF is generated in the biological medium containing cells except for ionic current, this work proposes to install capillary tubes in the electrode gaps for electrical insulation and cells delivery. By electrical measurements in the time domain and frequency domain, the exposure system is adapted for local generation of extremely high-intensity psPEF with the 3 dB bandwidth up to 4.2 GHz. Furthermore, biological experiments conducted on the developed exposure system verified its capability to permeabilize biological cells under the exposure of high-intensity psPEF.

Validation of a Multiclass Method for the Screening of 15 Antibiotic Residues in Milk Using Biochip Multi-array Technology and Its application to Monitor Real Samples

Veterinary drugs are extensively and legally consumed to treat and prevent disease in chattels but some are also used illegally as growth-stimulating agents. Inappropriate or intensive use of antibiotics can cause allergic reactions and, above all, antibiotic resistance. A multiclass approach for the screening of antimicrobial substances in milk was validated in consonance with Commission Decision 2002/657/EC and to the European guideline for the validation of screening methods for veterinary medicines. This biochip-based approach enables the simultaneous determination of a total of 13 sulphonamide, dapsone and trimethoprim. For monitoring of antibiotic residues, 53 UHT milk samples collected from Tehran, IR Iran were screened applying this technology. The result showed that for all antibiotic residues, the positivity threshold T was much more than the cut-off value Fm. A false positive rate of less than 5% was found for all antibiotics which are satisfactory. All detection capabilities (CCβ) were well below the Maximum Residue Level (MRL) set by the European Commission (100 µg/kg for the sum of all sulphonamides and 50 µg/kg for trimethoprim in milk). The screening results of 53 milk samples showed that 71.7% of samples were compliant and all positive samples were below the MRL set by European Commission. This study showed that the biochip-based technique is valid to identify and quantify antibiotic residues in milk at the studied validation levels. The method was rapid, easy, safe, and able to screen 13 sulphonamide, dapsone and trimethoprim from a single milk sample simultaneously with no sample preparation procedure (or just one-step centrifugation).

Validation of Simultaneous Biochip-based Method for Screening of 3 Beta-Lactam Families Residues in Cow's Milk in Accordance with the European Union Decision 2002/657/EC and its Application on Real Samples

Illegal and excessive use of veterinary antibiotics as a food additive for growth promotion in livestock can lead to allergic reactions and antibiotic resistance, which is a worldwide concern. A biochip-based semi-quantitative screening method of antimicrobial residues in milk was validated based on Commission Decision 2002/657/EC and the European guideline to validate screening methods for veterinary medicines. This multi-analytical screening method enables to determine of 3 beta-lactams (cefalexin, ampicillin, and cefuroxime) simultaneously. Analysis of 20 blank and 20 spiked milk samples showed that for all 3 antibiotic residues, the positivity threshold T was above cut-off value Fm, and no false-positive results were obtained for all 3 antibiotics. All detection capabilities (CCβ) were below Maximum Residue Level (MRL) authorized by European Commission. 47 UHT cow's milk samples collected from Tehran province, IR Iran, were screened, and compliance was found in 100% of samples. This study found that the biochip method is valid to determine antibiotic residues in milk samples at the measured validation levels. The method was fast, simple, and able to simultaneous screen three families of beta-lactams from a single milk sample with almost no sample preparation.

Differential effects of selective- and pan-PPAR agonists on experimental steatohepatitis and hepatic macrophages☆

BACKGROUND & AIMS

Peroxisome proliferator-activated receptors (PPARs) are essential regulators of whole-body metabolism, but also modulate inflammation in immune cells, notably macrophages. We compared the effects of selective PPAR agonists to those of the pan-PPAR agonist lanifibranor in non-alcoholic fatty liver disease (NAFLD), and studied isoform-specific effects on hepatic macrophage biology.

METHODS

Lanifibranor or selective PPARα (fenofibrate), PPARγ (pioglitazone) and PPARδ (GW501516) agonists were therapeutically administered in choline-deficient, amino acid-defined high-fat diet (CDAA-HFD)- and Western diet (WD)-fed mouse models of NAFLD. Acute liver injury was induced by carbon tetrachloride (CCl4). The role of PPARs on macrophage functionality was studied in isolated hepatic macrophages, bone marrow-derived macrophages stimulated with palmitic acid, and circulating monocytes from patients with NAFLD.

RESULTS

Lanifibranor improved all histological features of steatohepatitis in CDAA-HFD-fed mice, including liver fibrosis, thereby combining and exceeding specific effects of the single PPAR agonists. Its potent anti-steatotic efficacy was confirmed in a 3D liver biochip model with primary cells. Infiltrating hepatic monocyte-derived macrophages were reduced following PPAR agonist administration, especially with lanifibranor, even after short-term treatment, paralleling improved steatosis and hepatitis. Lanifibranor similarly decreased steatosis, liver injury and monocyte infiltration in the WD model. In the acute CCl4 model, neither single nor pan-PPAR agonists directly affected monocyte recruitment. Hepatic macrophages isolated from WD-fed mice displayed a metabolically activated phenotype. Lanifibranor attenuated the accompanying inflammatory activation in both murine palmitic acid-stimulated bone marrow-derived macrophages, as well as patient-derived circulating monocytes, in a PPARδ-dependent fashion.

CONCLUSION

Pan-PPAR agonists combine the beneficial effects of selective PPAR agonists and may counteract inflammation and disease progression more potently. PPARδ agonism and lanifibranor directly modulate macrophage activation, but not infiltration, thereby synergizing with beneficial metabolic effects of PPARα/γ agonists.

LAY SUMMARY

Peroxisome proliferated-activated receptors (PPARs) are essential regulators of metabolism and inflammation. We demonstrated that the pan-PPAR agonist lanifibranor ameliorated all aspects of non-alcoholic fatty liver disease in independent experimental mouse models. Non-alcoholic fatty liver disease and fatty acids induce a specific polarization status in macrophages, which was altered by lanifibranor to increase expression of lipid handling genes, thereby decreasing inflammation. PPAR isoforms have differential therapeutic effects on fat-laden hepatocytes, activated hepatic stellate cells and inflammatory macrophages, supporting the clinical development of pan-PPAR agonists.

Microfluidic Chip based direct triple antibody immunoassay for monitoring patient comparative response to leukemia treatment

We report a time and cost-efficient microfluidic chip for screening the leukemia cells having three specific antigens. In this method, the target blast cells are double sorted with immunomagnetic beads and captured by the 3rd antibody immobilized on the gold surface in a microfluidic chip. The captured blast cells in the chip were imaged using a bright-field optical microscope and images were analyzed to quantify the cells. First sorting was performed with nano size immunomagnetic beads and followed by 2nd sorting where micron size immunomagnetic beads were used. The low-cost microfluidic platform is made of PMMA and glass including micro size gold pads. The developed microfluidic platform was optimized with cultured B type lymphoblast cells and tested with the samples of leukemia patients. The 8 bone marrow samples of 4 leukemia patients on the initial diagnosis and on the 15th day after the start of the chemotherapy treatment were tested both with the developed microfluidic platform and the flow cytometry. A 99% statistical agreement between the two methods shows that the microfluidic chip is able to monitor the decrease in the number of blast cells due to the chemotherapy. The experiments with the patient samples demonstrate that the developed system can perform relative measurements and have a potential to monitor the patient response to the applied therapy and to enable personalized dose adjustment.

µPump: An open-source pressure pump for precision fluid handling in microfluidics

An open-source precision pressure pump system and control software is presented, primarily designed for the experimental microfluidics community, although others may find additional uses for this precision pressure source. This mechatronic system is coined 'µPump,' and its performance rivals that of commercially available systems, at a fraction of the cost. The pressure accuracy, stability, and resolution are 0.09%, 0.02%, and 0.02% of the full span, respectively. The settling time to reach 2 bar from zero and stabilize is less than 2 s. Material for building a four-channel µPump (approx. $3000 USD) or an eight-channel µPump (approx. $5000 USD) is approximately a quarter, or a third of the cost of buying a high-end commercial system, respectively. The design rationale is presented, together with documented design details and software, so that the system may be replicated or customized to particular applications. µPump can be used for two-phase droplet microfluidics, single-phase microfluidics, gaseous flow microfluidics and any other applications requiring precise fluid handling. µPump provides researchers, students, and startups with a cost-effective solution for precise fluid control.

Establishment of a 1, 4, 7, 10-tetraazacyclododecane-1,4,7,10-tetraacetic acid mono-N-hydroxysuccinimide ester (DOTA-NHS-ester) based lectin microarray for efficiently detecting serum glycans in gastric cancers

Development of cancers is involved in changes of a variety of glycans. Lectin microarray is one of the most powerful methodologies for investigation of glycan alterations in biological samples with its advantages of high through-put, selectivity and specificity of the technique. However, utilization of lectin microarrays available commercially keeps of great challenges. In this study, we took use of the molecular self-assembled monolayer technique to modify a gold surface with the reagent 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid mono-N-hydroxysuccinimide ester (DOTA-NHS-ester) in combination with 16-amino-1-hexadecanethiol hydrochloride. Cross-linking effect of DOTA-NHS-ester is brought about via activating three -OH ends to three terminals of succinylimidines, making selective binding of the terminal amino groups in proteins possible. We immobilized ten commercial lectins on the platform and measured changes of serum lectin-matched glycans in patients with gastric cancer. The results demonstrated that this biochip modification platform conferred impressive chemical surface stabilization, sensitivity and geometric images. We observed that all the serum glycans tested in the patients were significantly higher than those in the controls (P < 0.05). The biochip would provide a versatile platform for investigation of potential glycan biomarkers in making tumor diagnosis decision and analyzing escape of tumors from immunity.

Isolation and analysis of extracellular vesicles in a Morpho butterfly wing-integrated microvortex biochip

With the function of mediating intercellular communication between cells, extracellular vesicles (EVs) have been intently studied for their physiopathology and clinical application values. However, efficient EV isolation from biological fluids remains a significant challenge. To address this, this work constructs a new microvortex chip that can isolate EVs efficiently by integrating the lipid nanoprobe modified Morpho Menelaus (M. Menelaus) butterfly wing into microfluidic chip. M. Menelaus wing is well known for its orderly arranged periodic nanostructures and can generate microvortex when liquid passes through it, leading to increased interaction between EVs and M. Menelaus wing. In addition, the nanoprobe containing lipid tails can be inserted into EVs through their lipid bilayer membrane structure. Based on the described properties, high-throughput enrichment of EVs with over 70% isolation efficiency was realized. Moreover, it was demonstrated that the nanoprobe system based on M. Menelaus wing enabled downstream biological analysis of nucleic acids and proteins in EVs. Microvortex chips showed potential application value in efficient EV isolation for biomedical research and cancer diagnosis.

EXPOSE-R2 on the International Space Station (2014-2016): Results from the PSS and BOSS Astrobiology Experiments

EXPOSE facilities were ESA multiuser facilities mounted outside the International Space Station for astrobiology experiments. Between 2008 and 2016, three series of experiments were conducted involving chemical and biological samples to test their resistance and evolution in the space environment in low Earth orbit. In this Astrobiology special collection, results from two experiments of the EXPOSE-R2 campaign (2014-2016) are presented: Biofilm Organisms Surfing Space (BOSS) relating to biology and Photochemistry on the Space Station (PSS) dealing with astrochemistry.

Photochemistry on the Space Station-Antibody Resistance to Space Conditions after Exposure Outside the International Space Station

Antibody-based analytical instruments are under development to detect signatures of life on planetary bodies. Antibodies are molecular recognition reagents able to detect their target at sub-nanomolar concentrations, with high affinity and specificity. Studying antibody binding performances under space conditions is mandatory to convince space agencies of the adequacy of this promising tool for planetary exploration. To complement previous ground-based experiments on antibody resistance to simulated irradiation, we evaluate in this paper the effects of antibody exposure to real space conditions during the EXPOSE-R2 mission outside the International Space Station. The absorbed dose of ionizing radiation recorded during the 588 days of this mission (220 mGy) corresponded to the absorbed dose expected during a mission to Mars. Moreover, samples faced, at the same time as irradiation, thermal cycles, launch constraints, and long-term storage. A model biochip was used in this study with antibodies in freeze-dried form and under two formats: free or covalently grafted to a solid surface. We found that antibody-binding performances were not significantly affected by cosmic radiation, and more than 40% of the exposed antibody, independent of its format, was still functional during all this experiment. We conclude that antibody-based instruments are well suited for in situ analysis on planetary bodies.

Photochemistry on the Space Station-Aptamer Resistance to Space Conditions: Particles Exposure from Irradiation Facilities and Real Exposure Outside the International Space Station

Some microarray-based instruments that use bioaffinity receptors such as antibodies or aptamers are under development to detect signatures of past or present life on planetary bodies. Studying the resistance of such instruments against space constraints and cosmic rays in particular is a prerequisite. We used several ground-based facilities to study the resistance of aptamers to various types of particles (protons, electrons, neutrons, and carbon ions) at different energies and fluences. We also tested the resistance of aptamers during the EXPOSE-R2 mission outside the International Space Station (ISS). The accumulated dose measured after the 588 days of this mission (220 mGy) corresponds to the accumulated dose that can be expected during a mission to Mars. We found that the recognition ability of fluorescently labeled aptamers was not significantly affected during short-term exposure experiments taking into account only one type of radiation at a time. However, we demonstrated that the same fluorescent dye was significantly affected by temperature variations (-21°C to +58°C) and storage throughout the entirety of the ISS experiment (60% of signal loss). This induced a large variability of aptamer signal in our analysis. However, we found that >50% of aptamers were still functional after the whole EXPOSE-R2 mission. We conclude that aptamer-based instruments are well suited for in situ analysis on planetary bodies, but the detection step requires additional investigations.

Label-free detection of γ-aminobutyric acid based on silicon nanowire biosensor

γ-Aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system (CNS), which acts as a major biomarker for neurological disorders such as Parkinson's disease and Meningitis. To this end, the precise measurement of GABA molecule arisen as an important subject for the effective diagnosis and treatment of neurological disorders. However, yet highly sensitive biosensor systems which can analyze a wide range of GABA molecule in a fast response manner have not been reported. In this study, for the first time, a silicon nanowire field-effect transistor (FET) device based immunosensor was developed to detect GABA molecule. Zig-zag shaped silicon nanowires has been fabricated by electron beam lithography and the electrical property p-type FET device was validated through semiconductor analyzer. The optimal immobilizing condition of antibody against GABA molecule was determined by the fluorescent signal measurement. Various concentrations of GABA ranging from 970 fM to 9.7 μM were sensitively measured by conductance change on silicon nanowire-based through the immunoreactions. Further, owing to the ease of miniaturization and label-free system, we believe that the suggested device system has a potential to be utilized for an implantable biosensor to detect neurotransmitter in the brain and can create new opportunities in the field of diagnosis and treatment of neurological disorders.

Straight Channel Microfluidic Chips for the Study of Platelet Adhesion under Flow

Microfluidic devices have become an integral method of cardiovascular research as they enable the study of shear force in biological processes, such as platelet function and thrombus formation. Furthermore, microfluidic chips offer the benefits of ex vivo testing of platelet adhesion using small amounts of blood or purified platelets. Microfluidic chips comprise flow channels of varying dimensions and geometries which are connected to a syringe pump. The pump draws blood or platelet suspensions through the channel(s) allowing for imaging of platelet adhesion and thrombus formation by fluorescence microscopy. The chips can be fabricated from various blood-compatible materials. The current protocol uses commercial plastic or in-house polydimethylsiloxane (PDMS) chips. Commercial biochips offer the advantage of standardization whereas in-house chips offer the advantage of decreased cost and flexibility in design. Microfluidic devices are a powerful tool to study the biorheology of platelets and other cell types with the potential of a diagnostic and monitoring tool for cardiovascular diseases.

Smart Food Waste Recycling Bin (S-FRB) to turn food waste into green energy resources

Effective treatment of food waste is inherently difficult due to several factors, including its heterogeneous composition, high moisture content, and low heating value. To address these issues, this study aims to convert food waste into an energy resource using naturally occurring fermentative microorganisms embedded in wooden biochips (bio-catalysis), utilizing a "Smart Food Waste Recycling Bin" (S-FRB) system. High-throughput 16S rRNA gene sequencing analysis identified the major aerobic and facultatively anaerobic bacteria with alpha-diversity in terms of the Phylogenetic Diversity index ranging from 40.8 (initial stage) to 24.5 (mature stage), which indicates the microbial communities are relatively homogeneous and effective for use in the S-FBR. Operational results indicated that the organic content of food waste traded in the system increased from 53% up to 72% in the final end-product and achieved a mass reduction rate of approximately 80%. The heating value of the end-product, which was 3300 kcal/kg waste when measured by the differential scanning calorimeter (DSC) method, confirmed its high potential as a biofuel. Overall, the S-FRB system presents a practical approach for food waste treatment that solves the putrescible waste problem and maximizes utility through resource circulation.

Proliferation characteristics of cells cultured under periodic versus static conditions

In vitro culture models have become an indispensable tool for assessing a vast variety of biological questions in many scientific fields. However, common in vitro cultures are maintained under static conditions, which do not reflect the in vivo situation and create a non-physiological environment. To assess whether the growth characteristics of cells cultured at pulsed-perfused versus static conditions differ, we observed the growth of differentially cultured cells in vitro by life-cell time-lapse imaging of recombinant HEK293^YFPI152L cells, stably expressing yellow fluorescent protein. Cells were grown for ~ 30 h at 37 °C and ambient CO₂ concentration in biochips mounted into a custom-designed 3D printed carrier and were imaged at a rate of ten images per hour using a fluorescence microscope with environment control infrastructure. Cells in one chip were maintained under static conditions whereas cells in another chip were recurrently perfused with fresh media. Generated image series were quantitatively analyzed using a custom-modified cell detection software. Imaging data averaged from four biological replicates per culturing condition demonstrate that cells cultured under conventional conditions exhibit an exponential growth rate. In contrast, cells cultured in periodic mode exhibited a non-exponential growth rate. Our data clearly indicate differential growth characteristics of cells cultured under periodic versus static conditions highlighting the impact of the culture conditions on the physiology of cells in vitro.

Establishment of a protein biochip to detect serum IgG antibodies against IL-2 and soluble CD25 in hemophagocytic lymphohistiocytosis

BACKGROUND

Interleukin-2 (IL-2) and soluble CD25 (sCD25) are among the most important cytokines and diagnostic biomarkers in hemophagocytic lymphohistiocytosis (HLH). Detecting serum level of IL-2 and sCD25 is valuable for making clinical diagnosis and treatment decision in HLH.

METHODS

Since tests showing serum IgG antibody against IL-2 or sCD25 have never been carried out, a new protein biochip, which was modified with cysteine and activated sophorolipid (Cys-SL), was developed.

RESULTS

Limits of detection on the biochip were 78 pg/ml for IL-2 and 39 pg/ml for sCD25, respectively. The data showed that on-chip seroimmunological responses to IL-2 and sCD25 proteins were 20.8% and 83.1% and the seroprevalence of IL-2 and sCD25 IgG antibodies were 45.5% and 57.2%, respectively. Data collection for the seroprevalence of serum antigen-antibody complex of sCD25 was 68.8%. The new biochip model shared similar sensitivity and specificity to chemiluminescent immunoassay (CLIA) in its measuring capacity of serum sCD25.

CONCLUSIONS

We addressed and confirmed the involvement of serum IgG antibodies against IL-2 and sCD25 as well as Ag-Ab complex of sCD25 in HLH patients. Therefore, this biochip platform would offer a new technological substitution for clinical serological diagnosis of HLH.

Immobilization of Nonactivated Unfixed Platelets for Real-Time Single-Cell Analysis

Existing methods for measuring the response of individual platelets to stimulation are limited. They either measure each platelet at one discrete time-point (flow cytometry) or rely on adhesive ligands to immobilize platelets that concomitantly generate activation signals (microscopy). Such methods of immobilization make it impossible to assess resting platelets, the changes that occur as platelets transition from resting to active states, or the signals generated by soluble agonists, such as ADP and thrombin, or by mechanical stimulus, independently from those generated by the adhesive ligand. Here we describe a microscopy method that allows the immobilization of platelets to a glass cover slip without triggering platelet activation. This method makes use of specific antibodies that bind platelet PECAM-1 without activating it. Platelets can therefore be immobilized to PECAM-1 antibody coated biochips without causing activation and perfused with agonists or inhibitors. Using this method, platelets can be stimulated by an array of soluble agonists at any concentration or combination, in the presence or absence of inhibitors or shear forces. This chapter describes in detail this PECAM-1 mediated immobilized platelet method and its use for measuring changes in Ca²⁺ signaling in individual platelets under a number of different conditions. While we focus on the measurement of Ca²⁺ dynamics in this chapter, it is important to consider that the basic method we describe will easily lend its self to other measures of platelet activation (integrin activation, shape change, actin dynamics, degranulation), and may, therefore, be used to measure almost any facet of platelet activation.

Improving sensitivity of a miniaturized label-free electrochemical biosensor using zigzag electrodes

Cardiovascular disease (CVD) is a leading cause of death among chronic diseases worldwide. Therefore, it is important to be able to detect CVD biomarkers early so that patients can be diagnosed properly and begin treatment as soon as possible. To detect biomarkers more conveniently, point-of-care (PoC) biosensors, which are easy to use and are of low cost, are becoming even more necessary. This paper focuses on developing a label-free electrochemical biosensor with high sensitivity for PoC applications to detect CVD biomarkers such as S100 beta proteins and C-reactive proteins (CRP). To meet the requirements of a PoC application and to improve the measurement sensitivity for detection purposes, a three-electrode configuration was miniaturized and fitted onto a biochip. Computer simulation of an electrolyte current density was used to investigate several potential effective possibilities. It was found that an electrolyte current density at an edge tip structure near the working electrode (WE) and counter electrode (CE) was higher than at other locations. A zigzag structure was then designed at the edge near the WE and CE positions. With this design, we can obtain a higher total electrolyte current. This newly-designed biochip was then used to measure the electrochemical feature. It was found that the measurement efficiency was also improved using this newly designed biochip.

A Fully Integrated CMOS Fluorescence Biochip for DNA and RNA Testing

Design and successful implementation of a fully-integrated CMOS fluorescence biochip for DNA/RNA testing in molecular diagnostics (MDx) is presented. The biochip includes a 32×32 array of continuous wave fluorescence detection biosensing elements. Each biosensing element is capable of having unique DNA probe sequences, wavelength-selective multi-dielectric emission filter (OD of 3.6), resistive heater for thermal cycling, and a high performance and programmable photodetector. The dimension of each biosensor is 100µm×100µm with a 50µm×50µm N_well-P_sub photodiode acting as the optical transducer, and a ΣΔ modulator based photocurrent sensor. The measured photodetector performance shows ~116 dB detection dynamic range (10fA - 10nA) over the 25°C - 100°C temperature range, while being ~1 dB away from the fundamental shot-noise limit. To empirically demonstrate the compatibility of this biochip with MDx applications, we have successfully utilized the array and its thermal cycling capability to adopt a 7-plex panel for detection of 6 human upper respiratory viruses.

Ultrasensitive SPR detection of miRNA-93 using antibody-enhanced and enzymatic signal amplification

MiRNAs are endogenous noncoding RNA molecules. They play important gene-regulatory roles by binding to the mRNA of target genes thereby leading to either transcript degradation or translational repression. In virtually all diseases, distinct alterations of miRNA expression profiles have been found thus suggesting miRNAs as interesting biomarkers. Here, we present an SPR biosensor that utilizes disposable, injection-molded sensor chip/microfluidic hybrids combined with a lateral imaging optical system for parallel analysis of three one-dimensional spot arrays to detect miRNA-93. To increase the sensitivity of the biosensor we used two different amplification strategies. By adding an RNA-DNA-hybrid antibody for primary signal amplification, a limit of detection of 10 pmol/L was achieved. Based on that method we demonstrate the detection of miRNA-93 in total RNA lysate from HEK-293 cells. Utilizing an enzymatic signal amplification with Poly(A) polymerase, the sensitivity could be increased even further leading to a limit of detection of 1 fmol/L.

Comparative Study of Novel Fluorescent Cyanine Nucleotides: Hybridization Analysis of Labeled PCR Products Using a Biochip

This study investigated the synthesis and substrate properties of Cy5-labeled dUTP derivatives with different substituents, linkers between the dye unit and pyrimidine heterocycle and fluorophore charges. Fluorescently labeled nucleoside triphosphates were studied as substrates using multiplex PCR with Taq and Vent (exo-) DNA polymerases, the typical representatives of the A and B polymerase families. The efficiency of nucleotide incorporation during PCR was assessed with a multi-parameter hybridization analysis using a diagnostic DNA microarray. The hybridization analysis indirectly estimates the incorporation efficiency of dye-labeled nucleotides in multiplex PCR. Our results demonstrated higher efficiencies of substrates with electrically neutral dyes than electropositive and electronegative Cy5 residues.

Nanomaterial-based biosensors for detection of prostate specific antigen

Screening serum for the presence of prostate specific antigen (PSA) belongs to the most common approach for the detection of prostate cancer. This review (with 156 refs.) addresses recent developments in PSA detection based on the use of various kinds of nanomaterials. It starts with an introduction into the field, the significance of testing for PSA, and on current limitations. A first main section treats electrochemical biosensors for PSA, with subsections on methods based on the use of gold electrodes, graphene or graphene-oxide, carbon nanotubes, hybrid nanoparticles, and other types of nanoparticles. It also covers electrochemical methods based on the enzyme-like activity of PSA, on DNA-, aptamer- and biofuel cell-based methods, and on the detection of PSA via its glycan part. The next main section covers optical biosensors, with subsections on methods making use of surface plasmon resonance (SPR), localized SPR and plasmonic ELISA-like schemes. This is followed by subsections on methods based on the use of fiber optics, fluorescence, chemiluminescence, Raman scattering and SERS, electrochemiluminescence and cantilever-based methods. The most sensitive biosensors are the electrochemical ones, with lowest limits of detection (down to attomolar concentrations), followed by mass cantilever sensing and electrochemilumenescent strategies. Optical biosensors show lower performance, but are still more sensitive compared to standard ELISA. The most commonly applied nanomaterials are metal and carbon-based ones and their hybrid composites used for different amplification strategies. The most attractive sensing schemes are summarized in a Table. The review ends with a section on conclusions and perspectives.

A comparison of DNA fragmentation methods - Applications for the biochip technology

The efficiency of hybridization signal detection in a biochip is affected by the method used for test DNA preparation, such as fragmentation, amplification and fluorescent labelling. DNA fragmentation is the commonest methods used and it is recognised as a critical step in biochip analysis. Currently methods used for DNA fragmentation are based either on sonication or on the enzymatic digestion. In this study, we compared the effect of different types of enzymatic DNA fragmentations, using DNase I to generate ssDNA breaks, NEBNext dsDNA fragmentase and SaqAI restrictase, on DNA labelling. DNA from different Desulfovibrio species was used as a substrate for these enzymes. Of the methods used, DNA fragmented by NEBNext dsDNA Fragmentase digestion was subsequently labelled with the greatest efficiency. As a result of this, the use of this enzyme to fragment target DNA increases the sensitivity of biochip-based detection significantly, and this is an important consideration when determining the presence of targeted DNA in ecological and medical samples.

Identification of beta cell dysfunction at the pre-symptomatic stage of diabetes mellitus by novel analytical system: liquid biopsy measurements in femtograms

Background

Diabetes mellitus is produced and progresses as a consequence of complex and gradual processes, in which a variety of alterations of the endocrine pancreas, are involved and which mainly result in beta cell failure. Those molecular alterations can be found in the bloodstream, which suggests that we could quantify specific biomarkers in plasma or serum by very sensitive methods before the onset diabetes mellitus is diagnosed. However, classical methods of protein analysis such as electrophoresis, Western blot, ELISA, and liquid chromatography are generally time-consuming, lab-intensive, and not sensitive enough to detect such alteration in a pre-symptomatic state of the disease.

Method

A very sensitive and novel analytical detection conjugate system by using the combination of polyfluorophor technology with protein microchip method was developed.

Results

This innovative system facilitates the use of a very sensitive microchip assays that measure selected biomarkers in a small sample volume (10 μL) with a much higher sensitivity (92%) compare to common immune assay systems. Further advances of the application of this technology combine the power of miniaturization and faster quantification (around 10 min).

Conclusion

The power of this technology offers great promise for point-of-care clinical testing and monitoring of specific biomarkers for diabetes in femtogram level in serum or plasma. In conclusion, the results indicate that the technical performance of this new technology is valid and that the assay is able to quantified PPY-specific antigens in plasma at femtogram levels which can be used for identification of beta cell dysfunction at the pre-symptomatic stage of diabetes mellitus.

Gold Nanorod Array Biochip for Label-Free, Multiplexed Biological Detection

Gold nanorod (GNR) based label-free sensing has been attractive due to its unique property of localized surface plasmon resonance (LSPR). Compared to bulk gold, the SPR of GNRs is more sensitive to the refractive index change caused by biological binding in the close proximity. Numerous studies have reported biological detection in solution based GNR probes. However, the biosensing has the intrinsic problems of fluctuating readings and short storage time due to nanoparticle aggregation. In contrast, a chip-based nanorod biosensor is a more robust and reliable platform. We have developed a nanoplasmonic biosensor in a chip format by immobilizing functionalized GNRs on a (3-mercaptopropyl)trimethoxysilane modified glass substrate. The covalent Au-S bond ensures a strong GNR deposition on the substrate. This biochip exhibits a high sensitivity and stability when exposed to physiological buffer with high ionic strength. Another advantage of GNR as optical transducer is its LSPR peak dependence on the aspect ratio, which provides an ideal multiplexed detection mechanism. GNRs of different sizes that exhibit distinct SPR peaks are combined and deposited on designated spots of a glass substrate. The spectral shift of the respective peaks upon the biological binding are monitored for simultaneous detection of specific analytes. Coupled with a microplate reader, this spatially resolved GNR array biochip results in a high-throughput assay of samples as well as multiplexed detection in each sample. Since most biological molecules such as antibodies and DNA can be linked to GNR using previously reported surface chemistry protocol, the label-free nanosensor demonstrated here is an effective tool for protein/DNA array analysis, especially for detection of disease biomarkers.

Graphene-interfaced electrical biosensor for label-free and sensitive detection of foodborne pathogenic E. coli O157:H7

E. coli O157:H7 is an enterohemorrhagic bacteria responsible for serious foodborne outbreaks that causes diarrhoea, fever and vomiting in humans. Recent foodborne E. coli outbreaks has left a serious concern to public health. Therefore, there is an increasing demand for a simple, rapid and sensitive method for pathogen detection in contaminated foods. In this study, we developed a label-free electrical biosensor interfaced with graphene for sensitive detection of pathogenic bacteria. This biosensor was fabricated by interfacing graphene with interdigitated microelectrodes of capacitors that were biofunctionalized with E. coli O157:H7 specific antibodies for sensitive pathogenic bacteria detection. Here, graphene nanostructures on the sensor surface provided superior chemical properties such as high carrier mobility and biocompatibility with antibodies and bacteria. The sensors transduced the signal based on changes in dielectric properties (capacitance) through (i) polarization of captured cell-surface charges, (ii) cells' internal bioactivity, (iii) cell-wall's electronegativity or dipole moment and their relaxation and (iv) charge carrier mobility of graphene that modulated the electrical properties once the pathogenic E. coli O157:H7 captured on the sensor surface. Sensitive capacitance changes thus observed with graphene based capacitors were specific to E. coli O157:H7 strain with a sensitivity as low as 10-100 cells/ml. The proposed graphene based electrical biosensor provided advantages of speed, sensitivity, specificity and in-situ bacterial detection with no chemical mediators, represents a versatile approach for detection of a wide variety of other pathogens.

Bioinspired Assemblies and Plasmonic Interfaces for Electrochemical Biosensing

Electrochemical biosensing represents a collection of techniques that may be utilized for capture and detection of biomolecules in both simple and complex media. While the instrumentation and technological aspects play important roles in detection capabilities, the interfacial design aspects are of equal importance, and often, those inspired by nature produce the best results. This review highlights recent material designs, recognition schemes, and method developments as they relate to targeted electrochemical analysis for biological systems. This includes the design of electrodes functionalized with peptides, proteins, nucleic acids, and lipid membranes, along with nanoparticle mediated signal amplification mechanisms. The topic of hyphenated surface plasmon resonance assays is also discussed, as this technique may be performed concurrently with complementary and/or confirmatory measurements. Together, smart materials and experimental designs will continue to pave the way for complete biomolecular analyses of complex and technically challenging systems.

Detection and typing of human-infecting influenza viruses in China by using a multiplex DNA biochip assay

Rapid identification of the infections of specific subtypes of influenza viruses is critical for patient treatment and pandemic control. Here we report the application of multiplex reverse transcription polymerase chain reaction (RT-PCR) coupled with membrane-based DNA biochip to the detection and discrimination of the type (A and B) and subtype (human H1N1, human H3N2, avian H5N1 and avian H7N9) of influenza viruses in circulation in China. A multiplex one-step RT-PCR assay was designed to simultaneously amplify the HA and NA genes of the four subtypes of influenza A viruses and NS genes to discriminate type A and B viruses. PCR products were analyzed by a membrane-based biochip. The analytical sensitivity of the assay was determined at a range of 2-100 copies/reactions for each of the gene transcripts. Eighty one clinical samples, containing 66 positive samples with evident seasonal influenza virus infections, were tested, which gives the clinical sensitivity and specificity of 95.5% and 100% respectively. For the avian influenza samples, 3 out of 4 H5N1 samples and 2 out of 2 H7N9 avian samples were correctly identified. We argue this method could allow a rapid, reliable and inexpensive detection and differentiation of human-infecting influenza viruses.

Development of a novel protein biochip enabling validation of immunological assays and detection of serum IgG and IgM antibodies against Treponema pallidum pathogens in the patients with syphilis

In this study, we developed a novel protein biochip methodology that was characterized by dithiobis (succinimidyl undecanoate) (DSU) and specialized for detection of serum IgG and IgM antibodies against Treponema pallidum pathogens in the patients with syphilis, respectively. The biochips were validated by a dimension of atomic force microscope (AFM). The visualized detection limit of IgG antibody on the biochip was 0.39μg/ml. Finally, 286 serum samples from the patients with syphilis were simultaneously tested on the rTpN15-17-47 coated biochips. The results were evaluated in comparison with the assays of T. pallidum particle agglutination (TPPA) and the toluidine red unheated serum test (TRUST). The result demonstrated that the relative positive rate in the 286 patients by biochip was 99.0%, similar to that by TPPA (97.9%, P>0.05) and higher than that by TRUST, (76.2%, P<0.01). The detection specificities were 100% for the biochip and the TPPA and 97.0% for the TRUST. Thus, the protein biochip would provide a useful platform not only for enabling concurrent detection of the infectious antibodies directed against T. pallidum on a larger scale, but also for monitoring therapy modality of the disease.

Development of hydrogel biochip for in vitro allergy diagnostics

A hydrogel biochip was developed for the simultaneous quantitative determination of sIgE for 21 allergens and total IgE in human serum. The biochips are manufactured by photoinduced copolymerization of different molecules (allergens and antibodies) with gel-forming monomers resulting in the formation of three-dimensional hydrogel elements (1nl gel drops). After incubation of the biochip with the serum, the results are visualized using fluorescently labeled anti-IgE antibodies. Using biochips, serum samples from allergic patients and healthy donors were analyzed and good correlation with the results obtained using commercial EIA test systems of generally recognized quality (Dr. Fooke Laboratorien GmbH, Germany) was observed.

Expression of MT1E during the formation of hepatocellular carcinoma and its function in hepatocarcinoma cells

AIM: To investigate the expression of MT1E mRNA at different stages of liver cancer development and its biological functions in hepatocarcinoma cells.

METHODS: Rat hepatocellular carcinoma (HCC) models were induced by diethylnitrosamine (DEN), and the dynamic histological changes of liver tissue and the differential expression of MT1E gene were observed after the 4^th, 8^th, 16^th and 20^th weeks. Two siRNA targets toward MT1E gene were designed, recombinant plasmid was transfected into HCC cell line SMMC-7721, the gene expression of MT1E was determined using real-time quantitative PCR, and the cell viability was determined by MTT assay.

RESULTS: At the 4^th week and 8^th week the major pathological changes presented inflammatory changes in liver tissue, after 16^th week presented typical proliferation changes, until 20^th week developed into HCC. According to the gene chip results, the expression of MT1E was increased significantly after 16^th week, with significant difference compared with control group (gene chip reading: 11524 vs 5462). An effective siRNA target sequence in MT1E was got, the gene expression was decreased greatly at the 72 h after transfection compared with blank control group and negative control group (0.38 vs 1.00, 0.93, both P < 0.01). MTT assay result displayed, the cell growth and proliferation were depressed obviously when interference target was effectively transfected 144 h (0.1700 ± 0.0313 vs 0.5748 ± 0.0480, P < 0.01).

CONCLUSION: DEN-induced rat HCC models were established successfully, the expression of MT1E is increased obviously at the later stage of development of HCC, perhaps related to the malignant proliferation of tumor cells.

Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting

For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection molding and micro hot embossing have been proposed. These techniques, which require a proper photoresist, mask, UV light exposure, developing, and electroplating as a preprocess, are considered to have some problems. In this study, we propose a new microfabrication technology which consists of micro end-milling and powder blasting. This technique could be directly applied to fabricate the metal mold without any preprocesses. The metal mold with micro-channels is machined by micro end-milling, and then, burrs generated in the end-milling process are removed by powder blasting. From the experimental results, micro end-milling combined with powder blasting could be applied effectively for fabrication of the injection mold of biochips with micro fluidic channels.