We present a biosensing platform for the detection of proteins based on agglutination of aptamer coated magnetic nano- or microbeads. The assay, from sample to answer, is integrated on an automated, low-cost microfluidic disc platform. This ensures fast and reliable results due to a minimum of manual steps involved. The detection of the target protein was achieved in two ways: (1) optomagnetic readout using magnetic nanobeads (MNBs); (2) optical imaging using magnetic microbeads (MMBs). The optomagnetic readout of agglutination is based on optical measurement of the dynamics of MNB aggregates whereas the imaging method is based on direct visualization and quantification of the average size of MMB aggregates. By enhancing magnetic particle agglutination via application of strong magnetic field pulses, we obtained identical limits of detection of 25pM with the same sample-to-answer time (15min 30s) using the two differently sized beads for the two detection methods. In both cases a sample volume of only 10µl is required. The demonstrated automation, low sample-to-answer time and portability of both detection instruments as well as integration of the assay on a low-cost disc are important steps for the implementation of these as portable tools in an out-of-lab setting.

Study of the copper binding properties of metformin is important for revealing its mechanism of action as a first-line type-2 diabetes drug. A quantitative investigation of interactions between metformin and L-cysteine-copper complexes was performed. The results suggest that metformin could interact with biological copper, which plays a key role in mitochondrial function.

The mechanism of action (MOA) of the first line type-2 diabetes drug metformin remains unclear despite its widespread usage. However, recent evidence suggests that the mitochondrial copper (Cu)-binding action of metformin may contribute toward the drug’s MOA. Here, we present a novel biosensing platform for investigating the MOA of metformin using a magnetic microbead-based agglutination assay which has allowed us to demonstrate for the first time the interaction between Cu and metformin at clinically relevant low micromolar concentrations of the drug, thus suggesting a potential pathway of metformin’s blood-glucose lowering action. In this assay, cysteine-functionalized magnetic beadswere agglutinated in the presence of Cu due to cysteine’s Cu-chelation property. Addition of clinically relevant doses of metformin resulted in disaggregation of Cu-bridged bead-clusters, whereas the effect of adding a closely related but blood-glucose neutral drug propanediimidamide (PDI) showed completely different responses to the clusters. The entire assay was integrated in an automated microfluidics platform with an advanced optical imaging unit by which we investigated these aggregation–disaggregation phenomena in a reliable, automated, and user-friendly fashion with total assay time of 17 min requiring a sample (metformin/PDI) volume of 30 μL. The marked difference of Cu-binding action between the blood-glucose lowering drug metformin and its inactive analogue PDI thus suggests that metformin’s distinctive Cu-binding properties may be required for its effect on glucose homeostasis. The novel automated platform demonstrating this novel investigation thus holds the potential to be utilized for investigating significant and sensitive molecular interactions via magnetic bead-based agglutination assay.

Background: The pattern of skin diseases varies from one country to another and even from region to region of the same country. We are geographically placed in the tropical region with natural outcome of communicable diseases. We conducted this cross sectional study in a tertiary hospital of Bangladesh keeping the proposition in mind that infectious diseases occupy maximum percentage among skin and venereal diseases in outpatients in Bangladesh.Objectives: To classify the diseases attending the Skin & VD outpatient department of Enam Medical College Hospital (EMCH) and to draw comments and recommendations on the basis of findings.Materials and Methods: All patients irrespective of age and sex attending the OPD of Skin-VD Department of Enam Medical College Hospital during a 2-year time-period (from January 2009 to December 2010) were included in the study. Structured questionnaire, check-list and face-to-face interview (whenever necessary) were used as tools of data collection. Statistical analyses were done by SPSS version Windows 11.1.Results: Total number of patients was 12100. Most of the patients were aged (>18 years; 64.28%), dominated by male (61.63%), married (56.1%), literate (71.11%), coming from far (>5 km; 63.5%) and of middle class origin (59.73%). Out of the total cases, maximum (23.42%) were diagnosed as eczema, followed by infectious diseases (17%), acne (8.69%) and psoriasis (6.36%).Conclusion: In this study we found infectious diseases to occupy the second position next to eczema and our findings nullify the proposition that infectious diseases occupy maximum percentage among skin and venereal diseases in outpatients in Bangladesh. DOI: http://dx.doi.org/10.3329/jemc.v1i2.11465 J Enam Med Col 2011; 1(2): 67-70