On-Site Detection of Carcinoembryonic Antigen in Human Serum

Real-time connectivity and employment of sustainable materials empowers point-of-care diagnostics with the capability to send clinically relevant data to health care providers even in low-resource settings. In this study, we developed an advantageous kit for the on-site detection of carcinoembryonic antigen (CEA) in human serum. CEA sensing was performed using cellulose-based lateral flow strips, and colorimetric signals were read, processed, and measured using a smartphone-based system. The corresponding immunoreaction was reported by polydopamine-modified gold nanoparticles in order to boost the signal intensity and improve the surface blocking and signal-to-noise relationship, thereby enhancing detection sensitivity when compared with bare gold nanoparticles (up to 20-fold in terms of visual limit of detection). Such lateral flow strips showed a linear range from 0.05 to 50 ng/mL, with a visual limit of detection of 0.05 ng/mL and an assay time of 15 min. Twenty-six clinical samples were also tested using the proposed kit and compared with the gold standard of immunoassays (enzyme linked immunosorbent assay), demonstrating an excellent correlation (R = 0.99). This approach can potentially be utilized for the monitoring of cancer treatment, particularly at locations far from centralized laboratory facilities.

Determination of Acceptable Residual Limit by Using Newly Developed and Validated RP-HPLC Method for Citalopram Hydrobromide Residues that Swabbed from Surfaces of Pharmaceutical Manufacturing Equipment

In this study, easy and robust RP-HPLC method was developed and validated to determine acceptable residual limit of citalopram hydrobromide for cleaning procedures. The United States, Food and Drug Administration has mentioned that the acceptable limit for residues present in the equipment during processing or manufacturing should be based on logical criteria. In present study, acceptable residual limit for cleaning procedure of citalopram hydrobromide was calculated by using three approaches including therapeutic dose method, 10 ppm criteria and visual limit of inspection. The value by erapeutic dose approach was less among three calculated values hence, selected as acceptable residual limit (10.66 µg/25 cm2 ) for analytical method development and validation for the detection of this drug residues on the surfaces of manufacturing equipment. A RP-HPLC assay method was developed using C18 column and mobile phase containing mixture of methanol and ammonium acetate buffer (pH4.6) (70:30) with flow rate of 1.6 ml/min. System suitability parameters like theoretical plates and tailing factor were calculated for the validation of the developed method as per ICH Q2B guidelines. After analyzing recovery study data, it was found that stainless steel plate has minimum recovery (88.87%) and pre-analyzed tablet solution has maximum recovery (99.29%)

Development of Lateral Flow Immunochromatographic Strips for Micropollutants Screening Using Colorants of Aptamer Functionalized Nanogold Particles Part I Methodology and Optimization

A methodology of lateral flow immunochromatographic strip based on aptamer was developed for on-site detection of the small molecule micropollutants. In the present study, we try for the first time to investigate the feasibility of developing a strip assay for the analysis of micropollutants as methodological prototypes by combining the high selectivity and affinity of aptamers with the unique optical properties of nanogolds. This quantitative method was based on the competition for the aptamer between targets and DNA probes. Crucial parameters that might influence the sensitivity, such as the size of nanogolds, amount of aptamer, type and pH of streptavidin, type of nitrocellulose (NC) membrane, blocking procedure, and reading time, were systematically investigated to obtain the optimum assay performance. With the optimized conditions [nanogolds 25 nm, 50 μM aptamer, pH 8 of GSA (a type of streptavidin named “SA Gold,” which is a sulfhydrylization streptavidin), Millipore HFC 135 NC membrane, 1% bovine serum albumin as the blocking agent and added in the running buffer and sample pad soakage agents, and 20 min reading time] the aptamer-based lateral flow assay will show a low visual limit of detection and scanning reader LOD. The strip for on-site screening using colorants of aptamer functionalized nanogold particles did not require any complicated equipment and was a potential portable tool for rapid identification of micropollutants.

Spot-test identification and rapid quantitative sequential analys is of dipyrone

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drugand in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student’s t and the F tests. Considering the concentration in a 100 μL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

Spot-test identification and rapid quantitative sequential analysis of dipyrone

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drug and in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student's t and the F tests. Considering the concentration in a 100 µL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

72. Some problems of meteor astronomy: Introductory Lecture

We are now in an era of remarkable progress in the study of meteors. The electronic techniques developed at Jodrell Bank by Lovell, Clegg and others, and now by Davies, have culminated in giving us the power to observe the equivalent of 8th or 9th magnitude meteors for velocities, radiants and orbits. And certainly the limit has not yet been reached. The Harvard Super-Schmidt meteor cameras represent nearly the limit of current photographic-optical techniques; they approach close to the visual limit for very slow meteors, and with great precision, to 0·1 % in velocity and radiant.