A hybrid multifunctional physicochemical sensor suite for continuous monitoring of crop health

This work reports a first-of-its-kind hybrid wearable physicochemical sensor suite that we call PlantFit for simultaneous measurement of two key phytohormones, salicylic acid, and ethylene, along with vapor pressure deficit and radial growth of stem in live plants. The sensors are developed using a low-cost and roll-to-roll screen printing technology. A single integrated flexible patch that contains temperature, humidity, salicylic acid, and ethylene sensors, is installed on the leaves of live plants. The strain sensor with in-built pressure correction capability is wrapped around the plant stem to provide pressure-compensated stem diameter measurements. The sensors provide real-time information on plant health under different amounts of water stress conditions. The sensor suite is installed on bell pepper plants for 40 days and measurements of salicylic acid, ethylene, temperature, humidity, and stem diameter are recorded daily. In addition, sensors are installed on different parts of the same plant to investigate the spatiotemporal dynamics of water transport and phytohormone responses. Subsequent correlation and principal component analyses demonstrate the strong association between hormone levels, vapor pressure deficit, and water transport in the plant. Our findings suggest that the mass deployment of PlantFit in agricultural settings will aid growers in detecting water stress/deficiency early and in implementing early intervention measures to reduce stress-induced yield decline

Anti-angiogenic and toxicity effects of Derris trifoliata extract in zebrafish embryo

Introduction: Derris trifoliata has been traditionally used as folk for the treatment of , rheumatic joints, diarrhoea, and dysmenorrhea, and rotenoids isolated from the plant have shown to exhibit anti-cancer properties. This study aimed to assess the toxicity effects and antiangiogenic activity of extract of Derris trifoliata on zebrafish embryo model. Materials and Methods: Zebrafihs embryos were treated with aqueous extract of Derris Trifoliata to evaluate its effects on angiogenesis and zebrafish-toxicity. Angiogenic response was analyzed using whole-mount alkaline phosphatase (AP) vessel staining on 72 hours post fertilization (hpf) zebrafish embryos. Results: 1.0 mg/ml concentration was toxic to zebrafish embryos and embryos exposed to concentrations at 0.5 mg/ml and below showed some malformations. Derris trifoliata aqueous extract also showed some anti-angiogenic activity in vivo in the zebrafish embryo model wereby at high concentration inhibited vessel formation in zebrafish embryo. Conclusions: The anti-angiogenic response of extract of Derris trifoliata in zebrafish in vivo model suggest its therapeutic potential as anti-cancer agent

Sewage sludge heavy metal analysis and agricultural prospects for Fiji

Insoluble residues produced in Waste Water Treatment Plants (WWTP) as by products are known as sewage sludge (SS). Land application of SS, particularly in agricultural lands, is becoming an alternative disposal method in Fiji. However, currently there is no legislative framework governing its use. SS together with its high nutrient and organic matter contents, constitutes some undesired pollutants such as heavy metals, which may limit its extensive use. The focus of this study therefore was to determine the total concentrations of Pb, Zn, Cd, Cu, Cr, Ni and Mn in the SS produced at the Kinoya WWTP (Fiji) and in the non-fertile soil amended with the SS at 20, 40, 60, 80% application rates and in the control (100% Soil). The bioavailable heavy metals were also determined as it depicts the true extent of metal contamination. The treatment mixtures were then used to cultivate cabbage plants in which the total heavy metal uptake was investigated. Total Zn (695.6 mg/kg) was present in the highest amounts in the 100% SS (control), followed by Pb (370.9 mg/kg), Mn (35.0 mg/kg), Cu (65.5 mg/kg), Cr (20.5 mg/kg) and finally Cd (13.5 mg/kg) and hence a similar trend was seen in all treatment mixtures. The potential mobility of sludgeborne heavy metals can be classified as Ni > Cu > Cd > Zn > Mn > Cr > Pb. Total metal uptake in plant leaves and stems showed only the bioavailable metals Cu, Cd, Zn and Mn, with maximum uptake occurring in the leaves. Ni, despite being highly mobile was not detected, due to minute concentrations in the SS treatments. Optimum growth occurred in the 20 and 40% SS treatments. However maximum Cu and Mn uptake occurred in the 40% SS treatment thereby making the 20% treatment the most feasible. Furthermore the total and bioavailable metal concentrations observed were within the safe and permitted limits of the EEC and USEPA legislations

Pristine iota-Carrageenan and Chemically Functionalized Guar gum Polysaccharides for Metal-ion Complexation and CuS-based Nanocomposite Preparation

Natural polysaccharides are ubiquitous in nature and have been widely used in human history as food, materials, fuels, and medicine. To cope with climate crisis and develop a more sustainable economy, promoting the use of natural polysaccharides and other products from oxygenic photosynthesis is of great interest. In this work, anionic iota-carrageenan (CG) polysaccharide was employed to prepare an iota-carrageenan/CuS covellite (CG/CuS) nanocomposite using a gel/liquid interface precipitation process similarly to chemobrionics. This approach showed how pristine natural polysaccharides such as CG could be effortlessly utilized to develop high-end products for humidity and temperature sensing. Despite great potential of pristine natural polysaccharides in fabricating novel materials, chemical modifications of natural polysaccharides still play a crucial role in altering and enriching physical, chemical and biological properties, as well as applications of natural polysaccharides. Due to fascinating physicochemical properties, biodegradability, biocompatibility, natural abundancy and low cost, non-ionic guar gum (GG) polysaccharide was chosen as a model material to study how chemical modifications can substantially change properties of GG and extend its applications. An extensive analysis on reported chemical modification approaches of GG was conducted to examine recent advances in this field, as well as structure-property relationships and applications of GG-based materials. Among the four commonly used chemical reactions on GG, namely, nucleophilic reactions, graft polymerization, partial oxidation and cross-linking, nucleophilic reactions were adopted in this study due to the simplicity, accessibility and diversity of chemical reaction conditions and reagents. Different nucleophilic reactions were successfully carried out in aqueous medium at room temperature without using toxic organic solvents, allowing the introduction of different organic functional groups and moieties such as amine, thiol, xanthate, benzoic acid, catechol and tosylate to GG. The chemical modification of GG by xanthate and benzoic acid groups was chosen for further study due to their great potential applications. Being a soft base according to the hard and soft acid and base (HSAB) theory, xanthate functional groups on guar gum-xanthate (GG-X) allowed GG-X to coordinate more strongly to a wide range of soft metal ions, which have great potential in heavy metal removal, wastewater treatment, cross-linked hydrogel preparation, etc. In addition, GG-X offered dual functionalities as a surfactant and an organic matrix in the formation of GG-X/CuS nanocomposite colloidal dispersions, which showed printability and electrical responsiveness in humidity sensing. Benzoic acid moieties contain aromatic benzene rings and carboxylic acid groups, which offer interesting intermolecular interactions, coordination chemistry and swelling properties at mildly acidic environments to GG. Guar gum-benzoic acid (GG-BA) was found biocompatible to living cells (mouse embryonic fibroblasts and human mammary epithelial cells). Therefore, GG-BA could be explored further as coacervates and cross-linked hydrogels for biomedical applications, e.g. wound dressing, bioadhesives and drug delivery.Naturliga polysackarider är allmänt förekommande i naturen och har använts i stor utsträckning i människohistoria som mat, material, bränsle och medicin. För att klara av klimatkrisen och utveckla en mer hållbar ekonomi är det av stort intresse att främja användningen av naturliga polysackarider och andra produkter från syreproducerande fotosyntes. I detta arbete användes anjonisk jota-karragenan (CG) polysackarid för att framställa en jota-karragenan/CuS covellit (CG/CuS) nanokomposit med användning av en gel/vätskegränssnittsutfällningsprocess som liknar kemobrionik. Detta tillvägagångssätt visade hur orörda naturliga polysackarider utan ansträngning kunde användas för att utveckla avancerade produkter för fukt- och temperaturavkänning. Trots den stora potentialen hos orörda naturliga polysackarider vid tillverkning av nya material, spelar kemiska modifieringar av naturliga polysackarider fortfarande en avgörande roll för att förändra och berika fysiska, kemiska och biologiska egenskaper samt tillämpningar av naturliga polysackarider. På grund av fascinerande fysikalisk-kemiska egenskaper, biologisk nedbrytbarhet, biokompatibilitet, naturlig överflöd och låg kostnad, valdes nonjonisk guargummi (GG) polysackarid som modellmaterial för att studera hur kemiska modifieringar kan väsentligt förändra egenskaperna hos GG och utöka dess tillämpningar. En omfattande analys av rapporterade metoder för kemisk modifiering av GG genomfördes för att undersöka de senaste framstegen inom detta område, såväl som struktur-egenskapsförhållanden och potentiella tillämpningar av GG-baserade material. Bland de fyra vanligaste kemiska reaktionerna på GG, nämligen nukleofila reaktioner, ymppolymerisation, partiell oxidation och tvärbindning, antogs nukleofila reaktioner i denna studie på grund av enkelheten, tillgängligheten och mångfalden av kemiska reaktionsförhållanden och reagens. Olika nukleofila reaktioner genomfördes framgångsrikt i vattenhaltigt medium vid rumstemperatur utan att använda giftiga organiska lösningsmedel, vilket möjliggjorde införandet av olika organiska funktionella grupper och delar såsom amin, tiol, xantat, bensoesyra, katekol och tosylat till GG. Den kemiska modifieringen av GG av xantat- och bensoesyragrupper valdes för vidare studier på grund av deras stora potentiella tillämpningar. Som en mjuk bas från teorin om hård och mjuk syra och bas (HSAB) tillät xantatgrupper på guargummi-xantat (GG-X) GG-X att koordinera starkare till ett brett spektrum av mjuka metalljoner, som har stor potential vid borttagning av tungmetaller, avloppsvattenbehandling, tvärbunden hydrogelberedning etc. Dessutom erbjöd GG-X dubbla funktioner som ett ytaktivt ämne och en organisk matris vid bildning av GG-X/CuS nanokomposit kolloidal dispersion, som visade tryckbarhet och elektrisk känslighet vid fuktavkänning. Bensoesyradelar innehåller aromatiska bensenringar och karboxylsyragrupper, vilket erbjuder intressanta intermolekylära interaktioner, koordinationskemi och svällningsegenskaper i milt sura miljöer till GG. Guargummi-bensoesyra (GG-BA) visade sig vara biokompatibel med levande celler (embryonala musfibroblaster och humana bröstepitelceller). Därför skulle GG-BA kunna utforskas vidare som koacervat och tvärbundna hydrogeler för biomedicinska tillämpningar, t.ex. sårförband, bioadhesiver och läkemedelstillförsel

Effect of the air pressure on electro-Fenton process

Electro-Fenton process is considered a very promising tool for the treatment of waste waters contaminated by organic pollutants refractant or toxic for microorganisms used in biological processes [1-6]. In these processes H2O2 is continuously supplied to an acidic aqueous solution contained in an electrolytic cell from the two-electron reduction of oxygen gas, directly injected as pure gas or bubbled air. Due to the poor solubility of O2 in aqueous solutions, two dimensional cheap graphite or carbon felt electrodes give quite slow generation of H2O2, thus resulting in a slow abatement of organics. In this context, we report here a series of studies [7-9] on the effect of air pressure on the electro-generation of H2O2 and the abatement of organic pollutants in water by electro-Fenton process. The effect of air pressure, current density, mixing and nature of the organic pollutant was evaluated. [1] E. Brillas, I. Sirés, M.A. Oturan, Chem. Rev., 109 (2009) 6570-6631. [2] C.A. Martínez-Huitle, M.A. Rodrigo, I. Sirés, O. Scialdone, Chem. Rev. 115 (2015) 13362–13407. [3] M. Panizza, G. Cerisola, Chem. Rev. 109 (2009) 6541–6569. [4] I. Sirés, E. Brillas, M.A. Oturan, M.A. Rodrigo, M. Panizza, Environ. Sci. Pollut. Res. 21 (2014) 8336–8367. [5] C.A. Martínez-Huitle, S. Ferro, Chem. Soc. Rev. 35 (2006) 1324–1340. [6] B.P.P. Chaplin, Environ. Sci. Process. Impacts. 16 (2014) 1182–1203. [7] O. Scialdone, A. Galia, C. Gattuso, S. Sabatino, B. Schiavo, Electrochim. Acta, 182 (2015) 775-780. [8] J.F. Pérez, A. Galia, M.A. Rodrigo, J. Llanos, S. Sabatino, C. Sáez, B. Schiavo, O. Scialdone, Electrochim. Acta, 248 (2017) 169-177. [9] A.H. Ltaïef, S. Sabatino, F. Proietto, A. Galia, O. Scialdone, O. 2018, Chemosphere, 202, 111-118

Pressurized CO2 Electrochemical Conversion to Formic Acid: From Theoretical Model to Experimental Results

To curb the severely rising levels of carbon dioxide in the atmosphere, new approaches to capture and utilize this greenhouse gas are currently being investigated. In the last few years, many researches have focused on the electrochemical conversion of CO2 to added-value products in aqueous electrolyte solutions. In this backdrop, the pressurized electroreduction of CO2 can be assumed an up-and-coming alternative process for the production of valuable organic chemicals [1-3]. In this work, the process was studied in an undivided cell with tin cathode in order to produce formic acid and develop a theoretical model, predicting the effect of several operative parameters. The model is based on the cathodic conversion of pressurized CO2 to HCOOH and it also accounts for its anodic oxidation. In particular, the electrochemical reduction of CO2 to formic acid was performed in pressurized filter press cell with a continuous recirculation of electrolytic solution (0.9 L) at a tin cathode (9 cm2) for a long time (charge passed 67’000 C). It was shown that it is possible to scale-up the process by maintaining good results in terms of faradaic efficiency and generating significantly high concentrations of HCOOH (about 0.4 M) [4]. It was also demonstrated that, for pressurized systems, the process is under the mixed kinetic control of mass transfer of CO2 and the reduction of adsorbed CO2 (described by the Langmuir equation), following our proposed reaction mechanism [5]. Moreover, the theoretical model is in good agreement with the experimental results collected and well describes the effect of several operating parameters, including current density, pressure, and the type of reactor used. 1. Ma, S., & Kenis, P. J. (2013). Electrochemical conversion of CO2 to useful chemicals: current status, remaining challenges, and future opportunities. Current Opinion in Chemical Engineering, 2(2), 191-199. 2. Endrődi, B., Bencsik, G., Darvas, F., Jones, R., Rajeshwar, K., & Janáky, C. (2017). Continuous-flow electroreduction of carbon dioxide. Progress in Energy and Combustion Science, 62, 133-154. 3. Dufek, E. J., Lister, T. E., Stone, S. G., & McIlwain, M. E. (2012). Operation of a pressurized system for continuous reduction of CO2. Journal of The Electrochemical Society, 159(9), F514-F517. 4. Proietto, F., Schiavo, B., Galia, A., & Scialdone, O. (2018). Electrochemical conversion of CO2 to HCOOH at tin cathode in a pressurized undivided filter-press cell. Electrochimica Acta, 277, 30-40. 5. Proietto, F., Galia, A., & Scialdone, O. (2019) Electrochemical conversion of CO2 to HCOOH at tin cathode: development of a theoretical model and comparison with experimental results. ChemElectroChem, 6, 162-172

Towards the Development of Flexible Substrate Materials for Label-free Surface Enhanced Raman Spectroscopy (SERS) and Photo-induced Enhanced Raman Spectroscopy (PIERS)

This thesis is concerned with the label-free detection of small molecules and macromolecules using enhanced Raman spectroscopic techniques: Surfaceenhanced Raman Spectroscopy (SERS) and photo-induced enhanced Raman spectroscopy (PIERS). The work focuses on the development of reproducible and stable plasmonic nanoparticles (NPs) incorporated into flexible substrates to realise their SERS potential. The materials have been designed to fulfil the criteria of flexible and sensitive substrates in many applications with an emphasis in the biomedical field, especially within wound healing. A number of measurements on varying molecules were conducted to assess the SERS efficacy of the substrates. Most of the novel research presented in this thesis is proof-of-concept, laying the framework for further work. Chapter I highlights the importance of SERS and potential of PIERS with a thorough evaluation of the literature. Motivations behind the research as well as the aims of this work are addressed. Theoretical concepts are introduced with a touch on the mathematical background. Key principles and parameters influencing SERS and considerations are all covered to give a complete outline of the topic. The next few chapters focus on the results of this thesis. Chapter II provides synthetic routes for gold nanoparticles and includes a comparative study on the influence on nanoparticle shape on their subsequent SERS function. The effects of capping agents on the shape, size and stability of the NPs are examined. These are fully characterised and functional SERS testing is carried out using a range of molecules to fully evaluate their SERS ability. Surface modification is also attempted in this work with great concern given to overpowering solvent effects. Several biomarkers are introduced with qualitative SERS analysis. Duplex testing was performed to determine the specificity and sensitivity of the gold NPs. Chapter III starts investigating flexible materials as SERS substrates. These are readily available, low cost and biocompatible materials with gold NPs incorporated into them to become SERS active. Simple methods for synthesis 4 and data collection are presented as well as their SERS results. Paper and PDMS, whilst having some advantages lack clear Raman enhancement with inherent material signals dominating the spectra. Gelatine based hydrogels are chosen as an ideal candidate for SERS substrates. Many gelatine/polymer blends are synthesised and characterised to find the optimum gel regarding both mechanical and chemical permanence as well as SERS capability. Studies looking into cross-linking agents to establish the best synthetic protocol are executed. There is always a trade-off between highest functional efficiency and a more ‘green’ and sustainable approach. The PVA/hydrogel nanocomposite material exhibits valuable SERS whilst maintaining a facile methodology for synthesis and data acquisition. Chapter IV extends the SERS studies to biological macromolecules such as proteins and wound biomarkers. Both colloidal NPs and hydrogels are used as substrates. Concentration studies are conducted and attempts at correlating intensity with concentration are made, to limited realization. Real samples from patients are probed with patterns and trends hypothesised. These are corroborated against photographic evidence of the wound. Preliminary machine learning is employed to help classify the data with suggestive, positive results. Chapter V inspects PIERS on biomolecules with varying degrees of enhancements, but low concentration detection of glucose is reported. Different TiO2 substrates are investigated for their influence in the PIERS effect and are characterised appropriately. The preparation method, film thickness and wetting behaviour of the property are likely parameters that can impact the PIERS property of the substrate. Comparisons between SERS and PIERS reveal complex mechanistic considerations between the two phenomena. As a novel technique the possibilities to fully realise the potential of PIERS is yet to be explored, but there is a lot more research to be done to fully understand the effect. This thesis concludes with a summary of the key findings from the experimental work and presents possible avenues for further research to consolidate and advance the current work

Preparation of Novel Nanomaterial and Its Application in Food Industry

Nanotechnology has offered a wide range of opportunities for the development and application of structures, materials, or systems with new properties in the food industry in recent years. The developed nanomaterials could greatly improve not only food quality and safety but also the foods’ health benefits. Therefore, the great potential of nanomaterial has provided a new perspective for researchers to dive deep into the material at the nano level. It is essential to further come up with novel techniques, methods, and products that have a direct application to nanotechnology in food science. This Special Issue aims to provide an overview of the current and projected outcomes made on nanoscience and nanotechnology fields, from nanomaterials design, conception and characterization to its application in a variety of food-related industries. Researchers are invited to submit their up-to-date original research articles, review works, and short communications to this Foods Special Issue: “Preparation of Novel Nanomaterial and its Application in Food Industry