MTB-DR-RIF 9G membrane: a platform for multiplex SNP detection of multidrug-resistant TB.

The MTB-DR-RIF 9G membrane can detect by detecting multiple mutations in multiple codons. The MTB-DR-RIF 9G membrane possesses clinical applicability in point-of-care settings for the following reasons: (i) 100% similar results with that of the sequencing analysis for clinical samples, (ii) discrimination of the multiple mutations in multiple codons, (iii) a specific/non-specific hybridization ratio higher than 350:1, and (iv) the sensitivity was found to be 1-10 copies/test for detection and discrimination of the wild and mutant TB strains. Graphical abstract Schematic illustration of the effect of controller DNA on the hybridization of the immobilized probes (corresponding to the wild TB strain) with the PCR product of (a) wild TB strain and (b) mutant TB strain.

Immobilization techniques for microarray: challenges and applications.

The highly programmable positioning of molecules (biomolecules, nanoparticles, nanobeads, nanocomposites materials) on surfaces has potential applications in the fields of biosensors, biomolecular electronics, and nanodevices. However, the conventional techniques including self-assembled monolayers fail to position the molecules on the nanometer scale to produce highly organized monolayers on the surface. The present article elaborates different techniques for the immobilization of the biomolecules on the surface to produce microarrays and their diagnostic applications. The advantages and the drawbacks of various methods are compared. This article also sheds light on the applications of the different technologies for the detection and discrimination of viral/bacterial genotypes and the detection of the biomarkers. A brief survey with 115 references covering the last 10 years on the biological applications of microarrays in various fields is also provided.

9G DNAChip Technology: Self-Assembled Monolayer (SAM) of ssDNA for Ultra-Sensitive Detection of Biomarkers.

A 9G DNAChip obtained by allowing the formation of a self-assembled monolayer (SAM) of oligonucleotides appended with nine consecutive guanines on the chip surface has been applied in the detection of biomarkers. Using a 9G DNAChip, biomarker in the concentration range of 4 pg/mL to 40 fg/mL can be easily differentiated in the buffer matrix. Moreover, it is the first time that a biomarker with a concentration of 40 fg/mL has been detected in a mixture of proteins without use of any signal amplification technique.

HPV 9G DNA chip: 100% clinical sensitivity and specificity.

We describe a novel HPV 9G DNA chip test for the accurate and reliable genotyping of human papillomavirus (HPV). The HPV 9G DNA chip test established its efficiency in terms of a signal-to-background ratio (SBR) of 200, which is 50 times superior to commercial HPV DNA chips, and 100% target-specific hybridization at 25°C. We compared the genotyping results for the 439 clinical samples by the HPV 9G DNA chip test with the sequencing results for the MY11/GP6+ (M2) primer set-mediated PCR products. The discrimination of HPV genotypes in the 151 HPV-positive clinical samples by the HPV 9G DNA chip test were 100% identical with the sequencing analysis. The clinical sensitivities of HPV genotyping by the HPV 9G DNA chip test and a commercial HPV DNA chip test were 100% and 88%, respectively. However, the clinical specificities of HPV genotyping by the HPV 9G DNA chip test and the commercial HPV DNA chip test were 100% and 94%, respectively. The 100% clinical sensitivity and specificity of the HPV 9G DNA chip test make it a promising diagnostic tool for HPV genotyping.

Detection of multiple mutations in a single codon of genomic DNA.

The controller DNA technology allows the detection of multiple mutations in a single codon of genomic DNA. In this technology, the controller DNA is used to control the hybridization of target DNAs with the immobilized DNAs. The controller DNA technology is rapid, specific, and cost-effective for the following reasons, (i) final results in 40 min after PCR, (ii) detection and discrimination of the six mutations in a single codon, and (iii) high sensitivity.

Multiplex SNP detection in multiple codons for accurate drug therapy.

Multiplex SNP discrimination in the multiple codons of the genomic DNA is demonstrated by applying controller DNA technology (CDT) to MDR-TB 9G DNAChips. CDT allowed the efficient detection of 20 SNPs in five codons of the genomic DNA in 40 min. CDT could distinguish SNP targets to as low as 1 copy of the genomic DNA. 100% agreement with the sequencing analysis of clinical samples highlighted the clinical applicability of MDR-TB 9G DNAChips.

A new platform for a convenient genotyping system.

The high SNP discrimination ratio of 360 : 1, 100% target-specific hybridization at 25 °C, detection limit of 10(1) copies, and differentiation of 10(1) to 10(7) copies of the PCR product of high-risk HPV genotypes in clinical samples ensure the application of the 9G membrane in a convenient platform for DNA genotyping.

HPV genotyping 9G membrane test.

The results of the genital human papillomavirus (HPV) detection in 439 cervical samples by cervical cytology were compared with sequencing analysis and a newly developed HPV genotyping 9G membrane test. The excellent sensitivity and specificity of the HPV genotyping 9G membrane test was assured by a signal to noise ratio of more than 300 and a target hybridization to non-target hybridization ratio of 300 ~ 400 at 25 °C. The final results can be obtained in 29 min by simple loading of the hybridization and washing solutions and scanning the membranes without any drying steps or special handling. The 100% identical results of the HPV genotyping 9G membrane test with sequencing results in 439 clinical samples demonstrate significant clinical application for this test. HPV genotyping 9G membrane tests can identify and discriminate five HR-HPV genotypes which are prevalent in almost 87% of cervical cancer cases. Its simple handling makes the HPV genotyping 9G membrane test a very convenient platform for accurate HPV genotyping.

Characterization of the mixed self-assembled monolayer at the molecular scale.

The mixed SAM obtained by the self-assembly of the monothiolated calix[4]crown-5 receptor 1 and the subsequent addition of the thiolated alkylferrocene guest 3 was characterized at the molecular scale by the favorable receptor-guest interactions by using cyclic voltammetry (CV).