New competitive dendrimer-based and highly selective immunosensor for determination of atrazine in environmental, feed and food samples: the importance of antibody selectivity for discrimination among related triazinic metabolites

Recent Advances in Chemical Sensors for Soil Analysis: A Review

The continuously rising interest in chemical sensors’ applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed.

A Review on the Role and Performance of Cellulose Nanomaterials in Sensors

Sensors and biosensors play a key role as an analytical tool for the rapid, reliable, and early diagnosis of human diseases. Such devices can also be employed for monitoring environmental pollutants in air and water in an expedited way. More recently, nanomaterials have been proposed as an alternative in sensor fabrication to achieve gains in performance in terms of sensitivity, selectivity, and portability. In this direction, the use of cellulose nanomaterials (CNM), such as cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), and bacterial cellulose (BC), has experienced rapid growth in the fabrication of varied types of sensors. The advantageous properties are related to the supramolecular structures that form the distinct CNM, their biocompatibility, and highly reactive functional groups that enable surface functionalization. The CNM can be applied as hydrogels and xerogels, thin films, nanopapers and other structures interesting for sensor design. Besides, CNM can be combined with other materials (e.g., nanoparticles, enzymes, carbon nanomaterials, etc.) and varied substrates to advanced sensors and biosensors fabrication. This review explores recent advances on CNM and composites applied in the fabrication of optical, electrical, electrochemical, and piezoelectric sensors for detecting analytes ranging from environmental pollutants to human physiological parameters. Emphasis is given to how cellulose nanomaterials can contribute to enhance the performance of varied sensors as well as expand novel sensing applications, which could not be easily achieved using standard materials. Finally, challenges and future trends on the use of cellulose-based materials in sensors and biosensors are also discussed.

Soil Sensors and Plant Wearables for Smart and Precision Agriculture

Soil sensors and plant wearables play a critical role in smart and precision agriculture via monitoring real-time physical and chemical signals in the soil, such as temperature, moisture, pH, and pollutants and providing key information to optimize crop growth circumstances, fight against biotic and abiotic stresses, and enhance crop yields. Herein, the recent advances of the important soil sensors in agricultural applications, including temperature sensors, moisture sensors, organic matter compounds sensors, pH sensors, insect/pest sensors, and soil pollutant sensors are reviewed. Major sensing technologies, designs, performance, and pros and cons of each sensor category are highlighted. Emerging technologies such as plant wearables and wireless sensor networks are also discussed in terms of their applications in precision agriculture. The research directions and challenges of soil sensors and intelligent agriculture are finally presented.

Nanotechnology application in food packaging: A plethora of opportunities versus pending risks assessment and public concerns

Environmental factors, oxidation and microorganisms contamination, are the major causes for food spoilage, which leads to sensory features alteration, loss of quality, production of harmful chemicals and growth of foodborne pathogens capable to cause severe illness. Synthetic preservatives, traditional conserving methods and food packaging (FP), although effective in counteracting food spoilage, do not allow the real-time monitoring of food quality during storage and transportation and assent a relatively short shelf life. In addition, FP may protect food by the spoilage caused by external contaminations, but is ineffective against foodborne microorganisms. FP preservative functionalities could be improved adding edible natural antioxidants and antimicrobials, but such chemicals are easily degradable. Nowadays, thanks to nanotechnology techniques, it is possible to improve the FP performances, formulating and inserting more stable antioxidant/antimicrobial ingredients, improving mechanical properties and introducing intelligent functions. The state-of-the-art in the field of nanomaterial-based improved FP, the advantages that might derive from their extensive introduction on the market and the main concerns associated to the possible migration and toxicity of nanomaterials, frequently neglected in existing reviews, have been herein discussed.

Dendrimers as Soft Nanomaterials for Electrochemical Immunosensors

Electrochemical immunosensors are antibody-based affinity biosensors with a high impact on clinical, environmental, food, and pharmaceutical analysis. In general, the analytical performance of these devices is critically determined by the materials and reagents used for their construction, signal production and amplification. Dendrimers are monodisperse and highly branched polymers with three-dimensional structures widely employed as “soft” nanomaterials in electrochemical immunosensor technology. This review provides an overview on the state-of-the-art in dendrimer-based electrochemical immunosensors, focusing on those using polyamidoamine and poly (propylene imine) dendrimers. Special emphasis is given to the most original methods recently reported for the construction of immunosensor architectures incorporating dendrimers, as well as to novel sensing approaches based on dendrimer-assisted signal enhancement strategies.

Advances in electrochemical immunosensors

Immunosensors are compact tools on which antibody and antigen interactions are formed. The specific interaction between antibody and antigen is detected by using a transducer and an electrical signal is measured. This specific interaction between these molecules makes immunosensor very attractive for several applications in different fields. Electrochemical immunosensors are successful devices in selective and sensitive detection of several analytes. Electrochemical transducing methods such as voltammetric, potentiometric, conductometric or impedimetric have been utilized in different applications due to their excellent properties such as being low-cost, sensitivity and simplicity. In this chapter, the fundamentals of electrochemical immunosensors are summarized and different applications in food, environmental and clinical analyses are investigated and discussed.

Affinity Sensing Strategies for the Detection of Pesticides in Food

This is a review of recent affinity-based approaches that detect pesticides in food. The importance of the quantification and monitoring of pesticides is firstly discussed, followed by a description of the different approaches reported in the literature. The different sensing approaches are reported according to the different recognition element used: antibodies, aptamers, or molecularly imprinted polymers. Schemes of detection and the main features of the assays are reported and commented upon. The large number of affinity sensors recently developed and tested on real samples demonstrate that this approach is ready to be validated to monitor the amount of pesticides used in food commodities.

Fast atrazine degradation by the mixed cultures enriched from activated sludge and analysis of their microbial community succession

In this study, fast atrazine degradation by the mixed bacterial cultures from sewage sludge was investigated. The acquired activated cultures showed great capability in atrazine degradation. The biodegradation process was well fitted into a pseudo-first reaction kinetic model. Atrazine could inhibit the propagation of ammonium oxidation bacteria and nitrite oxidation bacteria, decreasing the ammonium removal rate and the accumulation of nitrite. Only 162-172 reads of Nitrosomonadaceae and no Nitrospirales were detected after atrazine was exposed to the mixed cultures. The bacterial community structures in the cultures under different inoculation conditions (with or without atrazine) were investigated to explore the mechanism of atrazine degradation. Our results show that the genera Thiobacillus and Ferruginibacter were the most possible candidates responsible for the degradation of atrazine.

Competitive amperometric immunosensor for determination of p53 protein in urine with carbon nanotubes/gold nanoparticles screen-printed electrodes: A potential rapid and noninvasive screening tool for early diagnosis of urinary tract carcinoma

Since p53 protein has become recognized biomarker for both diagnostic and therapeutic purposes in oncological diseases with particular relevance for bladder cancer, it is highly desirable to search for a novel sensing tool for detecting the patient's p53 level at the early stage. Here we report the first study on the development and validation of a novel disposable competitive amperometric immunosensor for determination of p53 protein at subnanomolar levels, based on p53 immobilization on gold nanoparticles/carbon nanotubes modified screen-printed carbon electrodes. The assay protocol requires the use of single anti-p53 mouse monoclonal antibody (DO-7 clone), able to recognize both wild-type and mutant p53. The developed immunosensor as well as the protocol of the electrochemical immunoassay were optimized by means of an experimental design procedure to assess the suitability of the device to be validated and applied for the determination of p53 in untreated and undiluted urine samples. It was found that the developed competitive immunodevice was able to achieve wide linear range detection of wild-type p53 from 20 pM to 10 nM with a low detection limit of 14 pM in synthetic urine samples, suggesting the sensor's capability of working in a complex sample matrix. The excellent performance results also in terms of selectivity, trueness and precision, coupled with the advantages of an easy preparation and low-cost assay in contrast to other methods which require very complex, time-consuming and costly nanostructured architectures, makes the developed competitive immunosensor an analytically robust diagnostic tool, valuable for implementation of screening and follow-up programs in patients with urologic malignancies.

Recent configurations and progressive uses of magnetic molecularly imprinted polymers for drug analysis

Since the introduction of the molecularly imprinting technology (MIT) in the 1970s, it becomes an emerging technology with the potential for wide-ranging applications in drug determination. With the rise of green chemistry, many researchers began to focus on the application and development of green materials which led to the breakthrough of molecularly imprinted polymers (MIPs) in the green chemistry. Because of the low concentration levels in the human matrices, almost adequate analytical methods should be used for quantification of drugs at the trace levels. In recent years there have been reported benefits of combining MIPs with additional features, e.g. magnetic properties, through the build-up of this type of material on magnetite particles. Magnetic molecularly imprinted polymer (MMIP) is a new material which is composed of magnetic material and non-magnetic polymer material and shares the characteristics of high adsorption capacity to template molecule, special selective recognition ability, and the magnetic adsorption property. These materials have been widely used in the different fields such as chemical, biological and medical science. This review describes the novel configurations and progressive applications of magnetic molecularly imprinted polymers to the drug analysis. Also, the advantages and drawbacks of each methodology, as well as the future expected trends, are evaluated.

Evaluation of flow injection analysis method with spectrophotometric detection for the determination of atrazine in soil extracts

A method for determining atrazine in soil extracts was evaluated by flow injection analysis with spectrophotometric detection. The method is based on the reaction of atrazine with pyridine in an acid medium followed by the reaction with NaOH and sulfanilic acid. Several analytical conditions were previously studied and optimized. Under the best conditions of analysis, the limits of detection and quantification were 0.15 and 0.45 mg L(-1), respectively, for a linear response between 0.50 and 2.50 mg L(-1), and a sampling throughput of 21 determinations per hour. Using the standard addition method, the maximum relative standard deviation of 17% and recovery values between 80 and 100% were observed for three extracts from soil samples with different composition. The proposed method is simple, low-cost and easy to use, and can be employed for studies involving atrazine in soil samples or for screening of atrazine in soils.

Competitive immunosensor based on gliadin immobilization on disposable carbon-nanogold screen-printed electrodes for rapid determination of celiotoxic prolamins

The first competitive disposable amperometric immunosensor based on gliadin-functionalized carbon/nanogold screen-printed electrodes was developed for rapid determination of celiotoxic prolamins. To date, no competitive spectrophotometric or electrochemical immunoassays have yet been successfully applied to gluten detection in processed food samples, which require the use of complex prolamin extraction solutions containing additives with denaturing, reducing and disaggregating functions. Thus, in this work, great effort was put into the optimization and performance evaluation of the immunosensor in terms of suitability as a screening tool for analysis of cereal-based food samples. For this purpose, aqueous ethanol or complex extraction mixtures, as the patented Cocktail Solution®, were proved effective in the extraction of gliadin. Good sensitivity was achieved after optimization of the immunocompetitive assay, giving limit of detection and limit of quantitation of 8 and 22 ng/ml of gliadin, respectively, for ethanol extracts. The immunosensor was proved to be suitable also for samples extracted with Cocktail Solution® after a proper dilution. Analysis of real samples of different flours proved the suitability of the immunosensing device as a powerful tool for safety assessment of raw materials used for the formulation of dietary products for celiac disease patients. This immunosensor combines good analytical performance using a very simplified set-up protocol with suitability for rapid screening analysis performed using inexpensive and portable instrumentation. Graphical abstract Depiction of the development and working principle of the competitive immunosensor.

Development of a highly sensitive noncompetitive electrochemical immunosensor for the detection of atrazine by phage anti-immunocomplex assay

The development of immunosensors for the detection of small molecules is of great interest because of their simplicity, high sensitivity and extended analytical range. Due to their size, small compounds cannot be simultaneously recognized by two antibodies impeding their detection by noncompetitive two-site immunoassays, which are superior to competitive ones in terms of sensitivity, kinetics, and working range. In this work, we combine the advantages of magneto-electrochemical immunosensors with the improved sensitivity and direct proportional signal of noncompetitive immunoassays to develop a new Phage Anti-Immunocomplex Electrochemical Immunosensor (PhAIEI) for the detection of the herbicide atrazine. The noncompetitive assay is based on the use of recombinant M13 phage particles bearing a peptide that specifically recognizes the immunocomplex of atrazine with an anti-atrazine monoclonal antibody. The PhAIEI performed with a limit of detection (LOD) of 0.2 pg mL(-1), which is 200-fold better than the LOD obtained using the same antibody in an optimized conventional competitive ELISA, with a large increase in working range. The developed PhAIEI was successfully used to assay undiluted river water samples with no pretreatment and excellent recoveries. Apart from the first demonstration of the benefits of integrating phage anti-immunocomplex particles into electrochemical immunosensors, the extremely low and environmentally relevant detection limits of atrazine attained with the PhAIEIS may have direct applicability to fast and sensitive detection of this herbicide in the environment.