Introduction: Gold nanoparticles (AuNPs) are often used as biosensors in biological markers and also in diagnostic kits. Spherical shaped AuNPs are red. These nanoparticles have high binding affinity with proteins, antibodies and antigens forming stable bioconjugates. Are widely used in lateral flow immunochromatography platform. Therefore, AuNPs are currently one of the main raw materials used to produce various diagnostic kits, including Sars-CoV-2. The assessment of their correct stability directly affects the customized production and quality of the diagnostics kits.Objectives: Evaluate the stability of in-house prepared gold nanoparticle solutions used in the manufacture of diagnostic tests using statistical methods for determining the appropriate shelf life under established storage conditions. Methodology:In-house based on adapted Turkevish method (1951), a gold nanoparticle (AuNP) solution was synthesized and characterized by ultraviolet-visible spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), dynamic scattering (DLS) and laser Doppler electrophoresis (LDE). The solution was analyzed at the time of manufacture (T0) and every 15 days for 90 days, under thermal stress conditions. The evaluation of the stability of the AuNP solution was based on the ISO Guide 35, which statistically evaluates the time that significant change occurs of the evaluation parameters, indicating the end of shelf life at a significance level of 0.05. Results:Statistical analysis shows that at T90 days, one of the evaluated parameters showed a significant change at a significance level of 0.05. |b1| > t95%, n-2 * s(b1) and, therefore, there is statistical evidence that proves that the final solution lost stability in this time. Arrhenius equation was used to determine the shelf life. Where, Storage=25°C, Stress=40°C, Activation Energy (Ea)=3, and then: Thermal Kinetic Ratio (Qt) = 5.2. That is, 2.5 months at 40°C is equivalent to 13 months at 25°C. Conclusion:AuNPs produced in-house have a shelf life of 1 month at room temperature. Based on the analysis of the main control parameters and statistical application, the validity attributable to the AuNP solution under study is 13 months at 25°C, bringing great savings to the production process, without loss of quality. New strategies for evaluating the stability of solutions should be considered in the future.
Introduction: Gold nanoparticles (AuNP) have a wide bond affinity to proteins, antibodies, and antigens. These bioconjugates show high stability and are applied as biological markers in the lateral flow immunochromatography to obtain the rapid diagnostic kits. Quantum yield (QY) is one of the parameters which characterizes the fluorescence process of a material. It is defined as the number of emitted photons relative to the number of absorbed photons, so that the greater the QY value, the greater emitted radiation. Determining the QY is very important to identify the most promising nanoparticles able to produce diagnostic kits with more sensibility, to secure faster and earlier diagnosis.Objectives: This work aims to evaluate the effect of different stabilizers in the QY of AuNP applied on the in vitro diagnostic production.Methodology: Three fluorescent AuNP were synthesized in-house (Laboratory of Diagnostic Technology, Bio-Manguinhos) using HAuCl4.3H2O, as precursor, and tryptophan (AuNP-T), bovine serum albumin (AuNP-B) and pepsin (AuNP-P) as stabilizers. QY values and fluorescence spectra were obtained using a spectrofluorophotometer (Shimadzu RF-6000) equipped with 150 W Xenon arc lamp and 1-cm quartz cell. Maximum excitation (λ EX ) and emission (λ EM ) wavelengths of each AuNP were obtained from spectra scan from 250 to 800 nm. Fluorescein 0.05 mol L -1 solution (FS), prepared in NaOH 0.1 mol L -1 , was used as fluorescence standard. absorbance at maximum λEX, refractive index and emission spectra areas were other parameters used in the QY calculation.Results: AuNP solutions showed absorbance and refractive values of 0.07 and 1.333, respectively. AuNP-B, AuNP-P and AuNP-T showed maximum λ EX /λ EM in 510/651 (QY: 1.0%), 315/405 (QY: 0.10%) and 300/360 nm (QY: 4.3%), respectively. The highest QY value observed to AuNP-T agree with the results described in the literature and can be attributed to the presence of the tryptophan in its structure, which is the amino acid whose luminescent process has been studied for many years. Conclusion:Tryptophan was the stabilizer whose nanoparticle (AuNP-T) exhibited the highest QY value (4.3%), so that its fluorescence characteristic secures it as a potential nanoparticle to be applied on the in vitro diagnostic production.
Introduction: According to WHO, Cancer is one of the leading causes of death with 10 million deaths occurred globally in 2020, and resistance to chemotherapy is a challenge. Metallic nanoparticles can accumulate in cancer tissue due to their size combined with the increased tissue/vascular permeability observed in cancer. Silver nanoparticles (AgNP), with an additional antimicrobial activity, poses as a promising antitumoral agent that can also be functionalized with natural products, biopharmaceuticals or monoclonal antibodies to increase its anticancer effects.Objectives: To evaluate in vitro antitumor properties of AgNP on human leukemia, breast cancer and melanoma cell lines.Methodology: Silver nanoparticles (AgNP) were synthesized by the borohydride reduction method and stabilized with boron and albumin (BSA) according to Misirli (2021; https://www.arca.fiocruz.br/ handle/icict/51648) and later characterized by ultraviolet-visible spectroscopy, dynamic light scattering, laser doppler electrophoresis and transmission electron microscopy. AgNP were washed and stored in suspension in specific buffer (500 μg/mL). Leukemia (K562), breast cancer (MCF-7 and MDA-MB-231) and melanoma (SK-MEL-28) cell lines were seeded in 96-well plates (5x10 3 cells/mL), maintained in a 5% CO 2 atmosphere at 37°C for 24h and treated with AgNP in multiple concentrations (from 0.015 to 150 ppm), each in triplicate. Cytotoxicity was evaluated using MTT method 48h after treatment. Statistical analysis and IC50 calculations were performed using Graph Pad Prism 9. Results:The AgNPs presented spherical, monodispersive particle, with an average size of 10 nm. When tested on SK-MEL-28 and MDA-MB-231 AgNP presented a cytotoxic effect at 150 ppm with a sharp decrease to basal values when tested at 15 ppm, from 86.66% to 2.36% in melanoma cell line SK-MEL-28, from 72.10% to 14.73% cytotoxicity. When tested on MCF7, a breast cancer cell line, AgNP displayed a cytotoxic effect from 1.5 to 150 ppm, with a IC50 of 19.06 ppm. We have observed that AgNP treatment on leukemia cell line K562, have had a maximum cytotoxic effect at 15 and 150 ppm (86.07 % and 71.11%, respectively) with a IC50 of 0.74 ppm. Comparison of different batches of AgNP resulted in similar IC50 for the cell lines tested. Conclusion:AgNP have in vitro cytotoxic activity on leukemia (K562), breast cancer (MCF-7 and MDA-MB-231) and melanoma (SK-MEL-28) cell lines. Further experiments are necessary to address selectivity index in non-tumorigenic cells and mechanism involved in AgNP-triggered cytotoxicity.
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