Simple Photometer Development For Educational Purposes in Natural Pigment Analysis

In this paper we will discuss the making of the simple photometer instrument to measure the absorbance of natural pigment crude extract. To make simple photometer, cuvette holder was printed using 3D Printing Machine, the development of simple photometer instrument also uses some components such as LED light (633 nm) as the light source, Photodiode-TSL250 as a detector and a variable resistor to set the initial intensity of light source. In this development, Arduino Uno was also used as USB data acquisition device to capture the signal from the instrument. The results of sample measurements between simple photometer instrument and UV-Vis 1800 spectrophotometer showed 98% regression coefficient of determination and simple photometer has a LOD and LOQ absorbance at 0.0267 and 0.0344. Simple photometer instrument was able to show similar response as commercial instrument. Through the development of simple photometer, student can easily understand the working principles of a spectrophotometer in natural pigment analysis that difficult to studied in detailed before.

Development and Evaluation of a Portable Spectrophotometer

INTRODUCTION: Colorimetric methods, such as proteins and glucose quantification, and enzymatic assays are widely performed in biochemical laboratories employing spectrophotometer equipment. Even being present in most of the labs that serve undergraduate students, low cost and portable spectrophotometers can be a valuable tool in high schools and for field studies. OBJECTIVES: We have assembled and evaluated a portable spectrophotometer, inspired in some open projects freely available on the Internet. MATERIALS AND METHODS: The system was built using an RGB LED as a light source and a light detector (TSL2561). These components were placed into the ends of a cuvette holder, which was designed in FREECAD software and fabricated in a 3D printer. The data collection system was developed using an Arduino UNO microcontroller, an LCD to show the absorbance, a micro SD card to store the results, and a push button to select the LED emitted light wavelength. All components were powered by battery bank of 2000mAh. The software was written in C++, and we used Arduino IDE 1.8.6. For the equipment evaluation, we ran protein (Bradford) and glucose (Somogyi-Nelson) essays comparing the results obtained from the developed equipment with the one used in our didactic lab (Biospectro SP-22). DISCUSSION AND RESULTS: The results obtained comparing both pieces of equipment shows a correlation coefficient of 0.99 for the both methods (Bradford and Somogyi-Nelson) in test-retest. The commercial equipment demonstrated the coefficient of variation higher than 10%, while developed spectrophotometer showed values lower than 5%. The power bank was able to supply energy to the equipment up to 12 hours. CONCLUSION: These results demonstrated high reliability for the data collected from the developed spectrophotometer. Besides the low cost, compact design and high battery autonomy. The developed equipment has presented as a valuable alternative for field experiments and in-class practices of biochemistry.

Experimental setup for light-to-heat NIR conversion measurements of gold nanoparticle solutions

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticle solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.

Experimental setup for light-to-heat NIR conversion measurements of gold nano-particles’ solutions

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticles’ solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.

Effect of Temperature on ADP-Induced Platelet Aggregation

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.