Itaconic Acid Cross-Linked Biomolecule Immobilization Approach on Amine-Functionalized Silica Nanoparticles for Highly Sensitive Enzyme-Linked Immunosorbent Assay (ELISA).

Biomolecule immobilization on nanomaterials is attractive for biosensors since it enables the capture of a higher concentration of bioreceptor units while also serving as a transduction element. The technique could enhance the accuracy, specificity, and sensitivity of the analytical measurements of biomolecules. However, it was found that the limitation in chemically binding biomolecules on nanoparticle surfaces could only cross-link between the C-terminal and N-terminal. Here, we report the facile one-step synthesis of amine-functionalized silica nanoparticles (AFSNPs). (3-Aminopropyl)triethoxysilane was used as a precursor to modify the functional surface of nanoparticles via the Stöber process. The biomolecules were immobilized to the AFSNPs through itaconic acid, a novel cross-linker that binds between the N-terminal and N-terminal and potentially improves proteins and nucleic acid immobilization onto the nanoparticle surface. The newly developed immobilization approach on AFSNPs for biomolecular detection enhanced the efficiency of ELISA, resulting in increased sensitivity. It might also be easily used to identify different pathogens for clinical diagnostics.

Sequential Injection Amperometric System Coupling with Bioreactor for In-Line Glucose Monitoring in Cell Culture Application.

We proposed a specially designed sequential injection (SI) amperometric system coupling with a bioreactor for in-line glucose monitoring in cell culture. The system is composed of three main parts which are the bioreactor, SI system, and electrochemical detection unit. The bioreactor accommodates six individual cell culture units which can be operated separately under different conditions. The SI system enables automatic in-line sampling and in-line sample dilution, with a specially designed mixing unit; therefore, it has the benefits of fast analysis time and less contamination risk. The use of 3D-printed microfluidic components, a mixing channel, and a flow cell helped to reduce operational time and sample volume. A disposable screen-printed electrode (SPE), modified with glucose oxidase (GOD), carbon nanotube, and gold nanoparticle, was used for detection. The developed system provided a linear range up to 3.8 mM glucose in cell culture media. In order to work with cell culture in higher glucose media, the in-line sample dilution can be applied. The developed SI system was demonstrated with mouse fibroblast (L929) cell culture. The results show that glucose concentration obtained from the SI system is comparable with that obtained from the conventional colorimetric method. This work can be further developed and applied for in vitro cell-based experiments in biomedical research.

Automatic Programmable Bioreactor with pH Monitoring System for Tissue Engineering Application.

Tissue engineering technology has been advanced and applied to various applications in the past few years. The presence of a bioreactor is one key factor to the successful development of advanced tissue engineering products. In this work, we developed a programmable bioreactor with a controlling program that allowed each component to be automatically operated. Moreover, we developed a new pH sensor for non-contact and real-time pH monitoring. We demonstrated that the prototype bioreactor could facilitate automatic cell culture of L929 cells. It showed that the cell viability was greater than 80% and cell proliferation was enhanced compared to that of the control obtained by a conventional cell culture procedure. This result suggests the possibility of a system that could be potentially useful for medical and industrial applications, including cultured meat, drug testing, etc.

Experiences with the uniqueness of Talanta.

Talanta has been known as one of the top ranking journals in (general) analytical chemistry. Applying a search term "Talanta" in Scopus, using the tool for analysis in there, some characteristics on Talanta were investigated. Tracing back for every 10 year period, by considering the citations relevant to the key words of the published papers, it can be seen that Talanta serves to report the works in the trends of that period. At the beginning period of Talanta, major contributions were from Europe and the USA and less contributions from Asia. After 30 years of Talanta, contributions from Asia, especially from China, have increased. Contributions from more countries around the globe have been increasing.

A simple platform with moving drops for downscaling chemical analysis incorporating smartphone detection.

A simple cost-effective device for downscaling chemical analysis with microliter-scale dropwise handing and smartphone detection is proposed. The platform was made from easily available materials. Drops of constant volume of analyte and reagent were placed onto a channel then moved by gravity force to mix and react with each other. The color change due to reaction was monitored with a smartphone. Assays of iron, copper and phosphate employing the platform were demonstrated with 1,10-phenanthroline, bicinchoninic acid and molybdate reagents, respectively. Kinetic study was also demonstrated for this simple device.

Towards Green Titration: Downscaling the Sequential Injection Analysis Lab-at-valve Titration System with the Stepwise Addition of a Titrant.

A downscaling in true titration based on a simple sequential injection analysis-lab-at-valve (SIA-LAV) has been proposed. A titrant solution was stepwise aspirated into a titration LAV chamber and a titration curve was obtained by monitoring the change in the solution color spectroscopically. This fully-automated SIA-LAV system required less volume of the sample/reagents, only a micro-liter scale, compared to the conventional method. The system was investigated with complexometric titration and acid-base titration. Application of the developed technique to some real samples has been demonstrated.

Microliter Operation for Determination of Nitrate-Nitrogen via Simple Zinc Reduction and Color Formation in a Well Plate with a Smartphone.

We propose a simple greener colorimetric method for the determination of nitrate-nitrogen by operating on a 96-well microplate and using a smartphone camera as a simple detector. A slurry containing 0.3 mg zinc was used for reduction of nitrate to nitrite, the reduction solution was transferred to a 96-well microplate to react with Griess reagent to form a pink azo dye product. The color product image was captured and processed by a smartphone camera and ImageJ software, respectively. The limit of detection and limit of quantitation were 0.04 and 0.10 mg/L nitrate-nitrogen, respectively, for the smartphone camera. Application to real samples was demonstrated. The proposed method results showed no significant difference (at 95% confidence) with the hydrazine reduction method. The proposed method could be used as an alternative method for on-site analysis due to the advantages of portability and rapidity; duplicate run of 20 samples could be carried out simultaneously in 12 min.

Application of a webcam camera as a cost-effective sensor with image processing for dual electrochemical - colorimetric detection system.

A webcam camera as an alternative cost-effective colorimetric sensor for the simple dual electrochemical - colorimetric detection system is proposed. Performance test of the system was investigated through electrochemical and colorimetric behaviors of redox reactions of potassium ferrocyanide complex. Image processing with two color systems, RGB and HSV, was applied together with various electrochemical techniques. Color responses obtained from the webcam correlated with electrochemical signals in various electrochemical techniques. The results from the proposed dual detection system agreed well with those obtained using conventional UV-vis spectroelectrochemical system reported previously. The application of proposed system was demonstrated for studying the redox reaction of catechin and electrochemical - colorimetric behaviors of Fe(II) and Fe(III) mixture.

Noodle based analytical devices for cost effective green chemical analysis.

Noodle based analytical devices are proposed for cost effective green chemical analysis. Two noodle based analytical platforms have been examined. Conditions for flow with laminar behaviors could be established. Detection may be via a webcam camera or a flatbed scanner. Acid-base reactions were chosen as a model study. The assays of acetic acid and sodium hydroxide were investigated. Apart from bromothymol blue, simple aqueous extract of butterfly pea flower was used as a natural reagent. Another model was the assay of copper (Cu2+) which was based on the redox reaction of copper (Cu2+) with iodide to produce tri-iodide forming brown/black product with starch which already exists in the noodle platform. Demonstration to apply the noodle platforms for real samples was made.