|
MICROFLUIDIC PAPER-BASED COLORIMETRIC SENSOR USING PYRROLIDINYL PEPTIDE NUCLEIC ACID-INDUCED SILVER NANOPARTICLES AGGREGATION FOR DNA DIAGNOSTICS
Prinjaporn Teengam, First author, chulalongkorn university
A paper-based colorimetric assay for DNA detection based on the pyrrolidinyl peptide nucleic acid (acpcPNA) - induced the nanoparticles aggregation was developed. The acpcPNA baring positive charged of lysine at C-terminus was designed as a probe to induce the aggregation of citrate anion-stabilized silver nanoparticles (AgNPs). In the presence of DNA target, the AgNPs remain stable due to the sufficient charge repulsion of anionic PNA-DNA duplexes and a resulting in changing the color of the solution. Of this idea, we report on a simple, inexpensive method with the potential for screening of middle east respiratory syndrome coronavirus (MERS-CoV), mycobacterium tuberculosis (MTB) and human papillomavirus (HPV) using colorimetric paper-based analytical devices. To demonstrate the effectiveness of this approach, the synthetic oligonucleotide target can be detected due to the color changing of AgNPs. The low detection limits of 1.53 nM (MERS-CoV), 1.27 nM (MTB) and 1.03 nM (HPV) were achieved. The acpcPNA probe exhibited very high selectivity for the complementary oligonucleotides over the single-base-mismatch, two-base-mismatch and non-complementary DNA targets. As the utility of this method, the proposed paper-based colorimetric DNA sensor has potential to be an alternative device for simple, rapid, sensitive and selective DNA detection.
Microfluidic Paper-based Device Using Gold Nanoparticle Modified Boron-doped Diamond Electrode for Determination of the Total Inorganic Arsenic
Kingkan Pungjunun, first author, Chulalongkorn
In this work, we report the use of microfluidic paper-based analytical device (µPAD) combined with gold nanoparticles modified boron-doped diamond electrode (AuNPs/BDDE) for determination of the total inorganic arsenic. The multistep detection including the preparation of AuNPs/BDDE via electrodeposition and the quantification of As(III) using square-wave anodic stripping voltammetry (SWASV) can be subsequently operated in one device. As principle of the total inorganic arsenic determination, the As(V) was firstly reduced by disodium thiosulfate (Na2S2O3) to As(III). The As(III) was then reduced on the AuNPs/BDD at low negative potential in the deposition step following the measurement in the stripping step. Under optimal conditions, the AuNPs/BDDE sensor was used to determine the total inorganic arsenic with linear ranges of 0.1 to 1.5 µg mL-1 (R2 = 0.9972) and detection limit down to 20 ng mL-1 (calculated as 3 value of the blank) in an accumulation period of 60 s. The proposed method was successfully applied for determination of the total inorganic arsenic in jasmine rice and brown rice samples. The advantages of this sensor for the inorganic arsenic determination include requirement of a small sample volume (µL scale), low-cost, short response time, readiness of use, high precision and accuracy.
Non-enzymatic electrochemical detection of glucose with a disposable paper-based sensor using a cobalt phthalocyanine–ionic liquid–graphene composite
Sudkate Chaiyo, PostDocs, Chulalongkorn
This work demonstrates for the first time the use of non-enzymatic electrochemical detection of glucose in paper-based analytical devices (PADs) as rapid, easy to use, inexpensive, and portable sensors for point-of-care monitoring. The assay is based on a carbon electrode screen-printed on paper and modified with cobalt phthalocyanine, graphene and an ionic liquid (CoPc/G/IL/SPCE). The results show that the modified electrode provides an increased surface area, improved conductivity and a good catalytic effect towards the oxidation of glucose. Due to the catalytic action of cobalt phthalocyanine oxidation of glucose occurs at less positive values. Under optimum conditions, glucose can be determined within wide linear dynamic ranges (0.01–1.3 mM and 1.3–5.0 mM) with a detection limit of 0.67 µM.
|
