The analytical methods used to determine germanium must be very sensitive as the germanium content in natural materials and waste rarely exceeds the mg/kg level. Among the numerous analytical techniques available, catalytic adsorptive stripping voltammetry (CAdSV) plays an essential role due to its remarkable sensitivity. After careful selection of the catalytic reagent and electrode material, the detection limits at sub-nM level are feasible. In the present work, it has been shown that the properties of lead and bismuth plated electrodes (plating solutions: quiescent 0.34 M HClO₄ containing 0.043 M of Bi(III) or stirred 0.2 M acetate buffer containing 0.003M Pb(II), E_plat = -0.9 V, Q_plat = 0.8 mC per mm²) differ considerably and only bismuth film electrodes enable germanium analytical signals to be obtained when Ge(IV)-catechol-V(IV)-HEDTA (HEDTA - N-hydroxyethyl-ethylene diamine-triacetic acid) catalytic system is employed. The bismuth film electrodes deposited on screen-printed carbon (Bi/SPE) supports provided well-shaped, sensitive, and reproducible signals of Ge(IV) (RSD = 2%) in the supporting electrolyte containing 0.05 M acetate buffer (pH of 4.4), 1 mM of catechol, 1 mM of V(IV) and 1.5 mM of HEDTA. The calibration curve was linear within the range from 2 to 30 nM of Ge(IV) (LOD = 1.5 nM). The applicability of the Bi/SPE electrodes was verified by measuring Ge(IV) in spiked snow water samples. The concentration determined by the standard addition method was equal to 10.05±0.11 nM of Ge(IV) that correlates well with the spiked value equal to 10 nM of Ge(IV).

Active packaging has gained interest in recent years. Despite protecting food from the environment, it can incorporate agents with specific properties in order to extend the shelf life of the food. As a requirement, it is essential that the active agent has a greater affinity for the food than for the packaging material and in this sense, essential oils (EOs) are potential candidates to be included in this new packaging system. The use of EOs can confer to food matrix antimicrobial and antioxidant properties, reduce the permeability of the packaging to water vapor and extend the shelf life of food products [1]. However, their use has been limited because they can provide strong flavor by interacting with other compounds present in the food matrix and modify the organoleptic characteristics. Although the nanoencapsulation of EOs can provide chemical stability and minimize the impact of EOs on the organoleptic properties decreasing their volatilization, still some physical modifications have been observed such as plasticizing effects or the color variations [2]. In this sense, the quality of food products and consumer safety can be increased through the use of sensors. This technology indicates when food products are degrading and gives information in the event that some specific packaging conditions have changed [3]. This work focuses to highlight the use of sensors as a new methodology to detect these undesirable changes in the food matrix in a short period of time.

References:

Sharma, S.; Barkauskaite, S.; Jaiswal, A.K.; Jaiswal, S. Essential oils as additives in active food packaging. Food Chem. 2021, 343, 128403, doi:10.1016/j.foodchem.2020.128403.

Ribeiro-Santos, R.; Andrade, M.; Sanches-Silva, A. Application of encapsulated essential oils as antimicrobial agents in food packaging. Curr. Opin. Food Sci. 2017, 14, 78–84, doi:10.1016/j.cofs.2017.01.012.

Soltani Firouz, M.; Mohi-Alden, K.; Omid, M. A critical review on intelligent and active packaging in the food industry: Research and development. Food Res. Int. 2021, 141, 110113, doi:10.1016/j.foodres.2021.110113.

Currently, medicinal plants have had a great relevance due to their beneficial healthy properties [1]. Many studies reflect that these biological properties, such as antioxidant, anti-proliferative, and antimicrobial activities are related to different bioactive molecules, including phenolic compounds. Although some of their mechanisms of action are unknown, in many cases it has been shown that various natural phenolic compounds are related to numerous bioactive properties, which have aroused the interest of the scientific community [2]. On this basis, the study focused on the analysis of five medicinal plants, such as Achillea millefolium L., Arnica montana L., Calendula officinalis L., Chamaemelum nobile (L.) All., and Taraxacum officinale Wiggers, all belonging to the Asteraceae family. After an initial review, a heat-assisted extraction with ethanol/water (80:20, v/v) was carried out to obtain extracts rich in phenolic compounds. Afterword’s, these extracts were evaluated regarding there antioxidant, antimicrobial, anti-inflammatory, cytotoxic, and enzymatic properties, together with the identification of the phenolic composition. The antioxidant activity measured through the TBARS assay, indicated that A. millefolium extracts presented an outstanding activity (0.013 mg/mL), while C. officinalis extract presented the best antimicrobial and antifungal activities with MIC values ranging from 0.25 to 0.5 mg/mL of extract. Regarding, the anti-inflammatory and cytotoxic activities, C. nobile extracts showed the greatest effect compared to the other species, with a IC₅₀ values of 15.2 µg/mL for the anti-inflammatory activity, and GI₅₀ values between 54 and 10.3 µg/mL, in the case of cytotoxic activity. On the other hand, A. montana extracts showed the highest content of phenolic compounds (119 mg total phenolic compounds/g of extract), being 3-O-caffeolyquinic acid, 5-O-caffeolyquinic acid and caffeic acid the most representative compounds. Concerning the enzymatic assays, both C. nobile and C. officinalis extracts showed the greatest inhibitory effects on two enzymes related to Alzheimer's disease, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Overall, this study provides scientific evidence to the assessment of the potential of medicinal plant extracts for the development of new products.

References

[1] Garcia-Oliveira, P., Fraga-Corral, M., Pereira, A. G., Lourenço-Lopes, C., Jimenez-Lopez, C., Prieto, M. A., & Simal-Gandara, J. (2020). Scientific basis for the industrialization of traditionally used plants of the Rosaceae family. Food Chemistry, 330, 127197.

[2] Garcia-Oliveira, P., Barral, M., Carpena, M., Gullón, P., Fraga-Corral, M., Otero, P., Prieto, M. A. & Simal-Gandara, J. (2021). Traditional plants from Asteraceae family as potential candidates for functional food industry. Food & Function.

Acknowledgments

The research leading to these results was supported by MICINN supporting the Ramón y Cajal grant for M.A. Prieto (RYC-2017-22891); by Xunta de Galicia for supporting the program EXCELENCIA-ED431F 2020/12, the pre-doctoral grant of P. García-Oliveira (ED481A-2019/295) and the program Grupos de Referencia Competitiva that supports the work of M. Barral-Martínez (GRUPO AA1-GRC 2018); by EcoChestnut Project (Erasmus+ KA202) that supports the work of B. Nuñez-Estevez. The authors are grateful to Ibero-American Program on Science and Technology (CYTED—AQUA-CIBUS, P317RT0003) and to the Bio Based Industries Joint Undertaking (JU) under grant agreement No 888003 UP4HEALTH Project (H2020-BBI-JTI-2019). The JU receives support from the European Union’s Horizon 2020 research and innovation program and the Bio Based Industries Consortium. The project SYSTEMIC Knowledge hub on Nutrition and Food Security, has received funding from national research funding parties in Belgium (FWO), France (INRA), Germany (BLE), Italy (MIPAAF), Latvia (IZM), Norway (RCN), Portugal (FCT), and Spain (AEI) in a joint action of JPI HDHL, JPI-OCEANS and FACCE-JPI launched in 2019 under the ERA-NET ERA-HDHL (n° 696295). The authors would like to thank the EU and FCT for funding through the project PTDC/OCE-ETA/30240/2017- SilverBrain - From sea to brain: Green neuroprotective extracts for nanoencapsulation and functional food production (POCI-01-0145-FEDER-030240). The authors are also gratefull to FCT, Portugal for financial support through national funds FCT/MCTES to the CIMO (UIDB/00690/2020); and L. Barros and R. Calhelha thank the national funding by FCT, P.I., through the institutional and individual scientific employment program-contract for their contracts.

A plasticizer is a substance intendent to increase flexibility and softness of the material to which it is added, , in order to improve its susceptibility to further processing. A plasticizer compound in the simplest sense is considered to be an organic solvent. There are many types of such compounds, such as animal fats, petroleum fractions, or all kinds of plant extracts. Plasticizers are used in the membranes of ion-selective electrodes and optodes forming their physical structure, however affecting as well the analytical performance of the sensors. Plasticizers can be also used in the process of creating microspheres that are incorporated with chemical indicators. With the change of environmental conditions, such structures can change their optical properties, becoming optodes in the microscale. In this work, the influence of two plasticizers - polar 2-Nitrophenyl octyl ether (o-NPOE) and non-polar bis(2-ethylhexyl) sebacate (DOS), on the optical response of microspheres sensitive to lipophilic ions was investigated. In addition, studies were also carried out considering the impact of the amount of plasticizer on the created microspheres properties - systems were prepared with a standard amount of the compound, its five-fold amount and without a plasticizer. The obtained results prove that in the case of the tested sensory system, the non-polar plasticizer works best, ensuring the obtaining of optodic microspheres with the highest linearity range of the calibration curve and the best sensitivity. When the amount of the selected plasticizer was adjusted, it was found that the best results can be obtained using the intermediate content of this ingredient. These result show, that plasticizer type and amount significantly influences analytical performance of optode microspehers.

This work was financially supported by National Science Centre (Poland) within the framework of the SONATA BIS project No. UMO-2018/30/E/ST4/00481. Aleksandra Kalinowska acknowledges financial support from IDUB project (Scholarship Plus programme).

The patterned immobilization of chemosensors into nano-/microarrays has often boosted application in diagnostics and environmental sensing applications. While this is a standard approach for biosensors, e.g. with antibodies, other proteins and DNA, arraying is not yet adopted widely for supramolecular chemosensors which are still predominantly used in solution systems. Here we introduce the patterned immobilization of cucurbit[n]urils (CBn).^{[1, 2]} into multiplexed microarrays and elucidate their prospects for advancement of surface-bound indicator-displacement assays (IDA) to detect small molecule analytes.^{[3, 4]} The microarrays were generated by microchannel cantilever spotting (µCS) of functionalized CBn and subsequent self-assembly of corresponding indicator dyes from solution. Enhanced sensitivity of surface-bound microarrays was established in demonstrations with small bioactive metabolites (spermine, amantadine, and cadaverine) compared to bulk assays. Furthermore, integration of the CBn/indicator microarrays into microfluidic channels provides an efficient way for real-time monitoring of the sensing process, allows easier handling and reduces need in analyte volume. The concept was further extended to differential sensing of analytes on diplex or multiplex CBn/indicator microarrays, opening-up a route to multi-component sensing of small molecule analytes in complex liquids.^[5]

[1] F. Biedermann and W. M. Nau, Angew. Chem. Int. Ed., 2014, 53 (22), 5694-5699

[2] C. Hu, L. Grimm, A. Prabodh, A. Baksi, A. Siennicka, P. A. Levkin, M. M. Kappes and F. Biedermann, Chem. Sci., 2020, 11, 11142

[3] J. Atwater, D. S. Mattes, B. Streit, C. B.‐Kninski, F. F. Loeffler, F. Breitling, H. Fuchs and M. Hirtz, Adv. Mater., 2018, 30, 1801632

[4] S. M. M. Dadfar, S. Sekula‐Neuner, U. Bog, V. Trouillet and M. Hirtz, Small, 2018, 14 (21), 1800131

[5] C. Zhong, C. Hu, R. Kumar, V. Trouillet, F. Biedermann and M. Hirtz, ACS Appl. Nano Mater., 2021

Chronic wounds are one of the many problems facing the medical community. These types of injuries are very common, but they are very difficult to diagnose. Currently, doctors assess wounds after a visual analysis. The problem with this assessment is that it varies from one doctor to another, and until after a few days it is not known if the wound is healing correctly or if on the contrary, it is becoming a chronic wound. These lesions are associated with imbalances between the degradation/regeneration processes of cell membranes derived from the activity of metalloproteases. Under normal conditions, these enzymes degrade damaged tissues so that they can be replaced by healthy ones. When their activity get out of control they begin to attack healthy and damaged tissues indistinctly, thus preventing wound healing. Therefore, the enzymatic activity of metalloproteases is the most appropriate biomarker for evaluating the state of a wound. In this work, it is proposed to measure the enzymatic activity of proteases indirectly, by determining the concentration of amino acids, derived from the degradation of membrane proteins. That is to say, the higher enzymatic activity, the higher concentration of amino acids. To carry out this measure, it has been designed a colorimetric sensory polymeric film based on ninhydrin, that changes color when getting in contact with amino acids. This change will be analyzed through the RGB parameters of a digital photo taken with a smartphone.

Introduction

Honey is a widely consumed product globally, so it is interesting to develop rapid and inexpensive methods for its authentication and quality control. On this line, two of the most studied parameters are total phenolic content (TPC) and antioxidant activity (AOX) [1].

The most common methods to analyze both parameters are spectroscopic assays using the Folin-Ciocalteu reagent (TPC) and 2,2′-azino-bis(3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt (ABTS) as a radical source (TEAC) [2]. These methods require a large expenditure of money and time and specialized personnel.

This study's main objective is to develop a suitable method that allows us to quantify the total phenolic content and determine the antioxidant activity in a faster and cheaper way than the conventional methods. To achieve this objective, a chromogenic sensor has been developed for the rapid and low-cost determination of the both parameters mentioned above in a single measurement. In addition to being a faster and cheaper method, as it is a polymeric sensor, it has advantages of lack of migration of the sensor subunits, manageability, and possibility of working in solid-state.

Experimental

This method is based on hydrophilic colorimetric films with pendant benzenediazonium salt motifs, which react with phenols rendering highly colored diazo groups. The preparation of the starting material is based on vinylpyrrolidone (VP), methyl methacrylate (MMA) and 4-amino styrene (SH₂). The benzenediazonium salt was formed from aniline pendant groups by immersion in an aqueous acid solution of sodium nitrite [3]. The intensity of the color allows us to determine both TPC and TEAC of the sample by analyzing a picture taken with a smartphone analyzed using the color-definition-parameters (RGB).

For the analysis with the honey samples, our film's 8 mm diameter discs were dipped in 10 ml of each honey sample for 2 h. After that time, the discs were removed from the sample and washed 3 times with NaOH 0.1M. Finally, photographs of the discs were taken, RGB parameters were analysed, and were compared with the antioxidant activity results and total polyphenol content obtained by conventional methods mentioned above.

Conclusions

We have developed a new method to quantify the total polyphenol content and determine the antioxidant activity with a single analysis in all honey samples studied. This method reduces the time and the cost of the analysis and does not require trained personnel, so it has great potential in the quality control of honey samples.

Acknowledgment

We gratefully acknowledge the financial support provided by FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2017-84501-R) and the Consejería de Educación—Junta de Castilla y León (BU061U16 and BU041G18) are gratefully acknowledged.

References

1. Thrasyvoulou, A., Tananaki, C., Goras, G., Karazafiris, E., Dimou, M., Liolios, V., Gounari, S. (2018). Span. J. Agric. Res, 57(1), 88-96.
2. Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M., Rice-Evans, C. (1999). Free Biol. Med. 26(9-10), 1231-1237
3. Vallejos, S., Moreno, D., Ibeas, S., Muñoz, A., García, F. C., García, J. M. (2019). Food Control. 106, 106684.

Introduction

Wound repair is a complex process formed for various phases (formation of fibrin clot or inflammatory response, among others). Metalloproteases (MMP) are enzymes that play a relevant role in this process since their functions are; regulate inflammation and degrade the extracellular matrix (ECM). This degradation allows the beginning of the cellular migration process and the formation of a new ECM.

Moreover, new studies show that an increase in enzyme activity of MMP could cause a chronic wound. Therefore, the control and knowledge of their enzyme activity have a great interest since it can help diagnose and treat this type of wounds [1].

On the other hand, Zn(II) is present as a structural and catalytic component of MMP, so the concentration of this ion could be correlated with the activity of MMP, and finally, this activity is correlated with the state of chronic wounds [2].

Hence, this study is based on the following objectives: (1) Chronic wound evaluation by medical personnel, (2) determination of Zn(II) in chronic wound through ICP-MS as a reference method, and (3) determination of Zn(II) in chronic wounds with an alternative, simpler, and more direct method.

The first two objectives will confirm the relationship between Zn(II) concentration and chronic wound severity, and the third objective is the main line of our study. It is oriented to developing an alternative method for Zn(II) detection “by the easy way”, using fluorimetric sensory polymers.

The last objective will be carried out through polymer science, specifically with polymer sensors. This kind of materials has obtained good results with simple procedures; thus, we proposed an inexpensive and rapid sensory material, which causes a change of fluorescent that can be measured both visually (naked eye) and smartphone boosted.

Our sensory motif is based on the quinoline family that is usually used to detect Zn(II) as we have seen in previous studies of the group.[2] Moreover, this method is cheap, simple, and the measurements can be easily carried out by unskilled personnel.

Polymer synthesis

The material was prepared by radical copolymerization of the different monomers: Vinylpyrrolidone (VP), methyl methacrylate (MMA), and the sensory monomer previously described (2). The radical polymerization was carried out in a silanized glass mould (100 μm thick) in an oxygen-free atmosphere at 60ºC overnight to obtain the polymeric film.

Results and Discussion

Preparation of biological samples from chronic wounds

Different kinds of samples (swab, wound bed, edge, capsular tissue, and bone) were obtained from chronic wounds of patients at Burgos University Hospital (HUBU). Each sample was then boiled in a pH 4.66 buffer solution for 10 min (20ml of buffer per gram of sample). Finally, the samples were cold filtered.

Conclusions

We have designed a new sensory material for the determination of Zn(II) in biological samples, that could be correlated with the enzyme activity of MMP and therefore, with the state of chronic wounds.

We have obtained the sensory material related to objective 3, and we are working on the study of chronic wound samples containing zinc, namely, objectives 1 & 2.

References

1. Xue, M., Le, N. T. V., & Jackson, C. J. (2006). Targeting matrix metalloproteases to improve cutaneous wound healing. In Expert Opinion on Therapeutic Targets (Vol. 10, Issue 1, pp. 143–155).
2. Adjepong, D., Jahangir, S., & Malik, B. H. (2020). The Effect of Zinc on Post-neurosurgical Wound Healing: A Review. Cureus, 12(1), 1–7.

3. Guembe-García, M., Vallejos, S., Carreira-Barral, I., Ibeas, S., García, F. C., Santaolalla-García, V., Moradillo-Renuncio, N., & García, J. M. (2020). Zn(II) detection in biological samples with a smart sensory polymer. Reactive and Functional Polymers, 154 (2020).

Indoor air quality is a topic of major importance for public health. Among the numerous chemical compounds that can be found in indoor air, BTEX (benzene, toluene, ethylbenzene and xylene) are considered as one of the most toxic volatile organic compounds (VOCs). The present contribution is focused on the use of an original approach to produce nanostructured materials based on tin oxide with unexplored features, especially for gas sensors. In this work, we combine two physical vapor deposition techniques based first on a pulsing injection of the reactive gas during the deposition and second focused on the "GLAD" (Glancing Angle Deposition) technique, which enables structuring various architectures. These active layers are deposited on micro-hotplate to produce micro-chemical gas sensors for the detection of BTEX.

Molecular nanoprobes with intrinsic enzyme-like activity represent a new wave of technology for rapid and sensitive detection of molecular targets. This work reports synthesis and characterization of novel and well-dispersed europium-doped ceria nanocrystals (EuCe NCs) with self-integrated catalytic and fluorescence sensing functions. The NCs have an average size of ∼5 nm and exhibit bright and stable fluorescence for more than 6 months in aqueous media. Their dual cooperative function as a catalyst and fluorescent probe was explored to develop a universally applicable fluorescence-based biosensing method to monitor enzyme reactions and quantitatively measure clinically relevant molecules. Sensing capabilities are demonstrated for detection of H₂O₂, glucose/glucose oxidase, lactate/lactate oxidase, phosphatase activity, and the catecholamine neurotransmitter, dopamine. Results indicate that EuCe NCs not only provide high enzyme-mimetic activity but also impart direct fluorescence sensing ability enabling all-in-one recognition, catalytic amplification, and detection of biomolecular targets. The EuCe nanozyme offers a stable alternative to the more complex systems based on the combined use of natural enzymes and fluorescent dyes. The high stability and fluorescent detection capabilities demonstrate that EuCe NCs have the potential to be used as a generic platform in chemical and biological sensing and bioimaging applications.