Urolithiasis is one of most common urogenital diseases. Its diagnosis and treatment require an efficient analytical method of determination of chemical composition of a urinary stone, ideally, during the surgery. Near infrared spectroscopy seems to be a promising method for intraoperative qualitative analysis of urinary stones (calcium oxalates, uric acid, etc.), providing fast measurements and portable equipment. In this work, the results of a pilot study of analyzing several urinary stones with different chemical composition (dry and soaked in saline) within the 939-1799 nm range are presented. The Principal Component Analysis results confirm the potential of this technique in qualitative analysis of urinary stones before their surgical removal.

Food safety is one of the most up-to-date subjects under the scope of the scientific community since is a fundamental issue for the general population. The desire to use a simple, inexpensive, easy-to-read package freshness indicator led to a multitude of proposals for package real-time sensors for food freshness indicators. The sensors' design strategy is to target a physical or chemical modification that occurs by the spoiling process, such as changes in temperature, moisture, or the detection of foodborne pathogens. One of the most common approaches consists in evaluating changes in pH since a significant amount of food spoilage occurs with significative alteration (e.g., acidity increases on dairy products). However, some safety concerns emerge from the use of complex artificial chemical molecules as pH indicators in active labels/packages for food. Natural occurring anthocyanins are a safe alternative to classic pH indicators and have been applied as sensitive molecules for pH changes aimed at the development of active labels and active packing for food. In this proposal, the latest scientific contributions on the application of anthocyanins in food spoilage sensors are briefly reviewed.

Arnica montana L. (Asteraceae family) is a plant commonly used in traditional medicine and several reports have characterized their bioactives, especially phenolic compounds. These compounds are well known for their numerous beneficial biological properties. In consequence, industry from the feed, food, cosmetic and pharmaceutical sectors are seeking extracts with high content in phenolic compounds that could be interesting for the development of bio-based applications. The objective of the present study was to characterize the phenolic profile of this species, as a first step for further optimization studies to obtain the highest amount of phenolic compounds. Therefore, A. montana was extracted with ethanol:water 80:20 (v/v) at room temperature during 1 hour and phenolic compounds were identified and quantified through HPLC (HPLC Dionex Ultimate 3000) coupled to a mass detector (TSQ Quantis). In the extract, up to nine phenolics were identified, belonging to different groups, namely: eriodictyol-O-glucuronide (flavanone), hispidulin and luteolin (flavones), kaempferol, 6-methoxykaempferol, quercetin-3-O-glucuronide (flavonols), quinic, caffeoylquinic and caffeic acids (hydroxycinnamic acids). However, only four of them could be quantified: 6-methoxykaempferol and the three hydroxycinnamic acids. The total phenolic content (mg/g of dry sample) was estimated in 27,34 mg/g, being the major compound caffeoylquinic acids (79,5 % of the total phenolics). It has been demonstrated that caffeoylquinic acids present anti-inflammatory and antioxidant potential, which have been linked to several beneficial effects. Thus, obtaining rich phenolics extracts of A. montana may display significant biological properties and could be a new ingredient for developing new applications in nutraceutical, cosmetic or pharmaceutical industries.

Tannins are a class of natural phenolic antioxidants represented by oligomers and polymers. Tannic acid (gallotannin) is one of the most typical compound widely distributed in plants. It posseses a wide application area in food technology and as a part of traditional herbal medicine in the treatment of various diseases. Tannic acid is one of the standards used for the medicinal plants quality control, for the plants rich of tannins. Therefore, development of sensitive and simple methods for tannic acid quantification is of practical interest. Glassy carbon electrode modified with multi-walled carbon nanotubes (GCE/MWCNTs) has been developed for the determination of tannic acid in medicinal plants. The improvement of tannic acid voltammetric response has been achieved using modified electrode due to the high electroactive surface area and electron transfer rate vs. bare electrode. Tannic acid electrooxidation at the GCE/MWCNTs is irreversible surface-controlled process involving transfer of two electrons and two protons on the first step. In differential pulse mode using Britton-Robinson buffer pH 2.0 as supporting electrolyte, the linear dynamic range of 0.10-7.5 μM with the detection limit of 0.038 μM have been obtained. Method has been applied for the analysis of infusions and decoctions of tannin-containing medicinal plants and compared to the spectrophotometric method. A positive correlations have been observed with ferric reducing power reflecting total content of phenolic compounds in the sample.

This paper presents the synthesis of fluorescein-modified hydrogel materials. The obtained materials were characterized by FT-IR spectroscopy. Then their sorption capacity in distilled water and Ringer's liquid was determined. Using digital microscopy, the morphology of the obtained systems was characterized.

Microplate-based methods are commonly used to conduct spectrophotometric-based assays on large batches of sample extracts, as they allow much greater throughput compared to traditional benchtop methods. However, many reported methods have not undergone a thorough method development/optimisation process; thus the significance of maintaining certain parameters and procedures is often unknown. This study investigated the importance of plate shaking prior to the absorbance measurement step in two common assays – total phenolic content (TPC) measured using the Folin–Ciocalteu method, and total antioxidant activity measured using the Ferric Reducing Antioxidant Power (FRAP) method. A comparison was conducted on 36 methanol extracts of chickpea (Cicer arietinum) kernel, which had TPCs ranging from 43-111 mg GAE (gallic acid equivalents)/L and FRAP values ranging from 25-67 mg TE (Trolox equivalents)/L. The absorbance of the samples was measured before and after the plate was shaken (300 secs); each sample was analysed in duplicate. For the TPC, the unshaken and shaken absorbance values showed a high correlation with one another (R² = 0.990); however, a paired samples t-test demonstrated a significant increase in absorbance after shaking (P<0.001; mean increase of 10.6%). Similarly, the unshaken and shaken absorbance values for FRAP showed a strong correlation (R² = 0.973), but again the shaken absorbance values were significantly higher (P<0.001, mean increase of 12.1%). This demonstrates the importance of plate shaking for ensuring complete reaction of the well contents prior to measuring their absorbance values. Furthermore, it highlights the need to closely follow the specified procedure when attempting to replicate or set up a microplate-based spectrophotometric method from the literature.

Heavy metal contamination in groundwater has become more prevalent due to the leaching of toxic wastes from various anthropogenic sources. When ingested, it can cause serious ill effects detrimental to human health. Hence, there is a need to monitor the levels of heavy metals in various water sources to ensure they will be fit for human consumption. Standard detection methods such as AAS and ICP-MS are typically used for quantifying the concentration of heavy metals. However, these require expensive equipment, not to mention the need for a trained and highly-skilled technician to operate the equipment. Nanosensors offer a low-cost alternative to these methods. By utilizing the localized surface plasmon resonance (LSPR), properties of noble metal nanoparticles such as AgNPs, colorimetric detection of heavy metals is made possible. Herein, we report the synthesis of humic acid-functionalized silver nanoparticles (HA-AgNPs) by borohydride reduction approach as a colorimetric nanosensor for Ni (II) detection in aqueous solutions. Humic acid acts as a capping agent that stabilizes the AgNPs in the colloidal mixture while providing functional groups for detecting heavy metals. The synthesized HA-AgNPs have an average hydrodynamic diameter of 42.9 nm, a polydispersity index of 0.438, and an LSPR peak of 400.6 nm. The nanosensor can be used for the colorimetric detection of Ni (II) ions within the linear range of 0.15 – 0.40 mM Ni (II) with a limit of detection (LoD) of 2.35 mg L^-1. The HA-AgNPs were shown to be selective in detecting Ni (II) ions; common metals in water such as Ca (II), Mg (II), Al (III), Zn (II), Na (I), and K (I) did not interfere with Ni (II) detection. As such, the HA-AgNPs can be used as a reliable and environment-friendly colorimetric nanosensor for rapid and point-of-need detection of Ni (II) ions in aqueous solutions.

Magnetite nanoparticles (MNPs) are quite preferable material for different bioassays because of their quite low toxicity both for cells and for mammals and big variety of their surface functionalization approaches. We have synthesized MNPs via simple and convenient co-precipitation method with preliminary filtration of FeCl₂ and FeCl₃ solution, under argon atmosphere and non-magnetic stirring. MNPs were citrate-stabilized and then modified stage-by-stage with tetraethoxysilane (TEOS), (3-Aminopropyl)triethoxysilane (APTES) and acylated with succinic anhydride resulting in carboxylated MNPs. Carboxylated MNPs were covalently bounded with folic acid antibody (FA-1) via 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). MNP-EDC-FA-1 were passed through test-stripe with the line containing folic acid-gelatin conjugate. The conjugation of MNP-EDC-FA-1 with folic acid was observed visually, and the magnetic signal distribution was scanned through the test-stripe with magnetic particle quantification technique (MPQ) developed earlier. Visually, the line with folic acid-gelatin conjugate on the test-stripe has turned dark, with color intensity strongly depending on MNP-EDC-FA-1 concentration. MPQ has shown that the great majority of MNP-EDC-FA-1 was bounded with acid-gelatin conjugate. MPQ technique allowed quantifying down to 5 ng of MNP-EDC-FA-1 in this experiment with MNPs synthesized, with strong peak at the acid-gelatin conjugate line.

MEMS capacitive pressure sensors have proven to be more reliable in terms of temperature drift and long-term stability when compared to MEMS piezoresistive pressure sensors. In this work, MEMS capacitive pressure sensor using micromachined technology has been designed and fabricated in this study. As the movable electrode, a silicon membrane is used, while the fixed electrode is a gold metal film on a glass substrate. There is no deformation of the silicon membrane when the pressure is equal on both sides. As a result of the pressure of 0 kPa applied to the silicon membrane, a capacitance exists between it and the metal electrode. Differences in pressures on both sides of the silicon membrane will cause the membrane to deform. Silicon membranes deform due to pressure differences, which affect the capacitance between metal electrodes and silicon membranes. MEMS capacitive pressure sensors benefit from the super mechanical properties of silicon material compared to metal-based sensors. Capacitive MEMS sensors are more desirable for applications requiring high performance and stability as compared to metal pressure sensors. This device is suited to measuring blood pressure with a measurement range of 0-45kPa. When applied pressure was 0 kPa, the measurement capacitance was 3.61 pF, and when 45 kPa was applied, it was 7.19 pF.

A nanoporous copper oxide materials synthesized by dealloying and thermal oxidation of amorphous CuZrAl ribbons, representing the novelty of this research, previously obtained by a melt-spinning process, was carried out in an aqueous HF solution by varying the holding time. These NPC structures are used as a template to achieve a 3D-NP-CuO material with different surface morphology. To investigate the structural and morphological properties of the obtained sandwich-type material, X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM/EDX), and ultraviolet-visible spectroscopy (UV-vis) were used. In summary, the dealloying and thermal oxidation of amorphous ribbons is an interesting approach to achieve 3D networks of NP-CuO with different morphologies and with a low production cost. These sandwich-type structures consisting of NPC and copper oxide nanowires (CuO/Cu₂O), combines the good electrical properties of NPC with the catalytic properties of copper oxide semiconductors making it a suitable material for photocatalysis, photoelectrodes in solar cells, battery applications and electrochemical sensors.