Gold on paper–paper platform for Au-nanoprobe TB detection

Abstract

Tuberculosis (TB) remains one of the most serious infectious diseases in the world and the rate of new cases continues to increase. The development of cheap and simple methodologies capable of identifying TB causing agents belonging to the Mycobacterium tuberculosis Complex (MTBC), at point-of-need, in particular in resource-poor countries where the main TB epidemics are observed, is of paramount relevance for the timely and effective diagnosis and management of patients. TB molecular diagnostics, aimed at reducing the time of laboratory diagnostics from weeks to days, still require specialised technical personnel and labour intensive methods. Recent nanotechnology-based systems have been proposed to circumvent these limitations. Here, we report on a paper-based platform capable of integrating a previously developed Au-nanoprobe based MTBC detection assay-we call it "Gold on Paper". The Au-nanoprobe assay is processed and developed on a wax-printed microplate paper platform, allowing unequivocal identification of MTBC members and can be performed without specialised laboratory equipment. Upon integration of this Au-nanoprobe colorimetric assay onto the 384-microplate, differential colour scrutiny may be captured and analysed with a generic "smartphone" device. This strategy uses the mobile device to digitalise the intensity of the colour associated with each colorimetric assay, perform a Red Green Blue (RGB) analysis and transfer relevant information to an off-site lab, thus allowing for efficient diagnostics. Integration of the GPS location metadata of every test image may add a new dimension of information, allowing for real-time epidemiologic data on MTBC identification.

Cellphone-based diagnostic devices

“…Huang and Ugaz developed a label-free DNA detection method based on the electrochemical dissolution activity of chromium and monitored by a cellphone ( Figure 13) [82]. ) colorimetric assay using a cellphone to detect mycobacterium TB complex DNA [83]. This approach relied on salt-induced color change as Au NPs were functionalized with single-stranded probe DNA.…”

Optoelectronics and Bio Devices on Paper Powered by Solar Cells

“…Lab-on-paper is a novel technology for fabricating simple, low-cost, portable, and disposable analytical devices holding great promise to aid global health, food quality control, and environmental monitoring [81,[100][101][102][103][104][105]. Lab-on-paper technology requires minimum fluid samples, compared to common devices, and the porous structure of the paper is solely responsible for fluid transportation.…”

One nanoprobe, two pathogens: gold nanoprobes multiplexing for point-of-care

“…In particular, systems based on gold nanoparticles (AuNPs) functionalized with thiol-modified DNA (Au-nanoprobes) have been extensively used for the detection and characterization of pathogens [10], including Mycobacterium tuberculosis [11,12]. We have previously reported a detection strategy for members of the M. tuberculosis complex (MTBC) based on the observable colorimetric alteration of an Au-nanoprobe colloidal suspension [15][16][17][18]. The colorimetric alteration results from the differential aggregation profiles of Au-nanoprobes induced by increased ionic strength in the presence or absence of the specific target sequence: presence of the complementary target sequence prevents aggregation and the solution remains red (localized surface plasmon resonance (LSPR) band at 525 nm); whereas absence of a specific target sequence leads to nanoparticles aggregation after salt addition and the solution turns blue (red-shift of the LSPR peak to longer wavelength, 600-650 nm) [10].…”

“…Map shows the geografical differences of Malaria and TB incidence where the highest rates are found predominantly in low-income countries in Africa and South America. This approach can be transposed into a simple and portable molecular diagnostic platform to be used at peripheral laboratories and/or point-of-need, coupled to a "smartphone" for data analysis and location metadata for real-time epidemiologic data [15].…”