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This study is an investigation for an inexpensive, simple and sensitive biosensor to detect prostate cancer using bioactivated-multi wall carbon nanotubes (MWCNTs, diameter of 20 nm, length of 5 µm) and a micro-pore filter paper (pore size of 0.45 µm). For the immunoassay of prostate specific antigen (PSA), which is a biomarker of prostate cancer, MWCNTs were activated with PSA antibody (monoclonal antibody of the prostate specific antigen) by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide sodium salt (NHSS). The activated MWCNTs were deposited on the micro-pore filter paper to use as a biosensor. The prepared biosensor can assay from 0 to 500 ng/mL of PSA level within 2 h with the detection limit of 1.18 ng/mL by the measurement of resistance change. The resistance change was caused by site selective interaction between PSA and PSA-antigen with an inexpensive bench top digital multimeter (5 1/2 digits). The detection range and sensitivity of the prepared sensor are good enough to diagnose the early stage of prostate cancer (> 4 ng/mL of PSA). This paper-based biosensor is about 20 times cheaper (fabricated biosensor price: 2.4 $) and over 10 times faster than enzyme-linked immunosorbent assay (ELISA), which is a general method for the detection of a specific protein in the modernized hospitals. Furthermore, the maximum detection limit is about 50 times higher than ELISA. [ABSTRACT FROM AUTHOR]

Writing with ink on a paper and the rapid diagnostics of diseases using paper cartridge, despite their remarkable diversities from application perspective, both involve the motion of a liquid from a source on a porous hydrophilic substrate. Here we bring out a generalization in the pertinent dynamics by appealing to the concerned ensemble-averaged transport with reference to the underlying molecular picture. Our results reveal that notwithstanding the associated complexities and diversities, the resultant liquid transport characteristics on a paper matrix, in a wide variety of applications, resemble universal diffusive dynamics. Agreement with experimental results from diversified applications is generic and validates our unified theory. [ABSTRACT FROM AUTHOR]

Aims: Present-day screening of the diabetic foot involves the Semmes Weinstein Monofilament Test for evaluating loss of sensibility, while testing for intrinsic muscle weakness is not implied. Just as with the early detection of sensibility loss, early detection of intrinsic muscle weakness might have important implications for the prevention of both ulceration and deformity in patients with diabetes. The purpose of this study is to investigate the prevalence of patients with diabetes presenting intrinsic muscle weakness of the hallux, but with a normal sensibility of the sole of the foot.Methods: A cross-sectional study design was applied. Intrinsic muscle function of the hallux was measured with the Paper Grip Test, while sensibility of the sole of the foot was measured with the Semmes Weinstein Monofilament Test 5.07/10-g.Results: In a period of three months a total of 266 patients with diabetes (mean age 60, 134 females (50%), 177 type 2 diabetes mellitus (67%)) met the inclusion criteria and were examined for both intrinsic muscle weakness of the hallux and sensibility of the soles of the feet. The results showed that intrinsic muscle weakness was present more frequent in patients with impaired sensibility (P=0.001), also 20% of the population had intrinsic muscle weakness in the presence of normal sensibility. Multivariate regression analysis showed that only age is associated with patients with diabetes presenting normal sensibility but impaired intrinsic muscle function (P=0.017).Conclusions: The Paper Grip Test could have added value to current physical examination of the feet in patients with diabetes. [ABSTRACT FROM AUTHOR]

The lack of sensitivity is a major problem among microfluidic paper-based analytical devices (μPADs) for early disease detection and diagnosis. Accordingly, the present study presents a method for improving the enrichment factor of low-concentration biomarkers by using shallow paper-based channels realized through a double-sided wax-printing process. In addition, the enrichment factor is further enhanced by exploiting the ion concentration polarization (ICP) effect on the cathodic side of the nanoporous membrane, in which a stationary sample plug is obtained. The occurrence of ICP on the shallow-channel μPAD is confirmed by measuring the current–voltage response as the external voltage is increased from 0 to 210 V (or the field strength from 0 to 1.05 × 104 V m−1) over 600 s. In addition, to the best of our knowledge, the electroosmotic flow (EOF) speed on the μPAD fabricated with a wax-channel is measured for the first time using a current monitoring method. The experimental results show that for a fluorescein sample, the concentration factor is increased from 130-fold in a conventional full-thickness paper channel to 944-fold in the proposed shallow channel. Furthermore, for a fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) sample, the proposed shallow-channel μPAD achieves an 835-fold improvement in the concentration factor. The concentration technique presented here provides a novel strategy for enhancing the detection sensitivity of μPAD applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] We present nanoparticle-based lateral-flow test-strip devices. [•] We review nanomaterial-based paper biosensors. [•] We discuss future opportunities for nanomaterial-based paper biosensors. [ABSTRACT FROM AUTHOR]

The article presents the study conducted by researcher George Whitesides regarding the use of the three-dimensional (3) microfluidic devices made of ordinary paper and tape. Whitesides and his colleagues have impregnated the stacked layers of papers with usual photoresist to determine its other usage aside from DNA analysis, proteomics and inkjet technology. They found out the paper-based device is also useful in medical diagnostics.