State-of-the-Art of (Bio)Chemical Sensor Developments in Analytical Spanish Groups

(Bio)chemical sensors are one of the most exciting fields in analytical chemistry today. The development of these analytical devices simplifies and miniaturizes the whole analytical process. Although the initial expectation of the massive incorporation of sensors in routine analytical work has been truncated to some extent, in many other cases analytical methods based on sensor technology have solved important analytical problems. Many research groups are working in this field world-wide, reporting interesting results so far. Modestly, Spanish researchers have contributed to these recent developments. In this review, we summarize the more representative achievements carried out for these groups. They cover a wide variety of sensors, including optical, electrochemical, piezoelectric or electro-mechanical devices, used for laboratory or field analyses. The capabilities to be used in different applied areas are also critically discussed

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry was held on 1–15 July 2021. The scope of this online conference was to gather experts that are well-known worldwide who are currently working in chemical sensor technologies and to provide an online forum for the presention and discussion of new results. Throughout this event, topics of interest included, but were not limited to, the following: electrochemical devices and sensors; optical chemical sensors; mass-sensitive sensors; materials for chemical sensing; nano- and micro-technologies for sensing; chemical assays and validation; chemical sensor applications; analytical methods; gas sensors and apparatuses; electronic noses; electronic tongues; microfluidic devices; lab-on-a-chip; single-molecule sensing; nanosensors; and medico-diagnostic testing

Development of optical microchip sensor for biomolecule detection

Optical sensors play vital roles in many applications in today’s world. Photonic technologies used to design and engineer optical sensing platforms can provide distinctive advantages over conventional detection techniques. For instance, when compared to electronic and magnetic sensing systems, optical sensors require physically smaller equipment and have the capability for delivering more analytical information (e.g. spectroscopic signatures). In addition, demand for low-cost and portable bio-analyte detections is a growing area for applications in healthcare and environmental fields. Among other factors to achieve reliable results in terms of selectivity and sensitivity is key for the detection of bio-analytes with analytical relevance. Commonly used bio-analytical techniques (e. g. high performance liquid chromatography) have been appropriately designed based on qualitative and quantitative analysis. However, the requirement of expensive equipment, and complexity of procedures (e.g. biomolecule labelling, calibrations, etc.) restrict the board applicability and growth of these techniques in the field of biosensing. Optical sensors tackle these problems because they enable selective and sensitive detection of analytes of interest with label-free, real-time, and cost-effective processes. Among them, optical interferometry is increasingly popular due label-free detection, simple optical platforms and low-cost design. An ideal substrate with high surface area as well as biological/chemical stability against degradation can enable the development of advanced analytical tools with broad applicability. Nanoporous anodic alumina has been recently envisaged as a powerful platform to develop label-free optical sensors in combination with different optical techniques. This thesis presents a high sensitive label-free biosensor design combining nanoporous anodic alumina (NAA) photonic structures and reflectometric interference spectroscopy (RIfS) for biomedical, food and agricultural applications. NAA is a suitable optical sensing platform due to its optical properties; a high surface area; its straightforward, scalable, and cost-competitive fabrication process, and its chemical and mechanical stability towards biological environments. Our biosensor enables real-time screening of any absorption and desorption event occurring inside the NAA pores. A proper selection of bio-analytes were able to be detected using this platform which offers unique feature in terms of simplicity and accuracy. The most relevant components of this thesis are categorised as below: 1. Self-ordered NAA fabrication and detection of an enzymatic analyte as a biomarker for cancer diagnosis: Fabrication of NAA photonic films using two step electrochemical anodization and chemical functionalisation. Detection of trace levels of analyte enzyme and its quantification by selective digestion. The NAA photonic film with the enzyme acts as a promising combination for a real-time point-of-care monitoring system for early stages of disease. 2. NAA rugate filters used to establish the binding affinity between blood proteins and drugs: Design, fabrication, and optimisation of NAA anodization parameters using sinusoidal pulse anodization approach (i.e. anodization offset and anodization period) to produce rugate filter photonic crystals that provide two comparative sensing parameters. Establishment of highly sensitive and selective device capable for drug binding assessments linked to treating a wide range of medical conditions. 3. NAA bilayers and food bioactive compound detection: Design, fabrication, and optimisation of NAA anodization parameters (i.e. anodization time and number of anodization steps) to obtain NAA bilayered photonic structures that display the effective response of NAA geometry with different types of nano-pore engineering. The photonic properties of the NAA bilayer were studied at each layer of nano-structure under specific binding of human serum albumin and quercetin as target agent. 4. Single nucleotide polymorphism (SNP) detection: The design and implementation of a Ligation-Rolling Circle Amplification assay to detect a single nucleotide polymorphism associated with insecticide resistance in a pest beetle species, Tribolium castaneum. This proof-of-concept SNP detection assay has the potential to provide a method compatible with a biosensor platform such as NAA. This demonstrates the first step towards the potential development of a genotyping biosensor, and a real-world application of insect insecticide resistance monitoring. The results presented in this thesis are expected to enable innovative developments on NAA sensing technology that could result in highly sensitive and selective detection systems for a broad range of bio-analytes detections.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Chemical Engineering, 201

Biosensors and CMOS Interface Circuits

abstract: Analysing and measuring of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. Point of care diagnostic system, composing of biosensors, have promising applications for providing cheap, accurate and portable diagnosis. Owing to these expanding medical applications and advances made by semiconductor industry biosensors have seen a tremendous growth in the past few decades. Also emergence of microfluidics and non-invasive biosensing applications are other marker propellers. Analyzing biological signals using transducers is difficult due to the challenges in interfacing an electronic system to the biological environment. Detection limit, detection time, dynamic range, specificity to the analyte, sensitivity and reliability of these devices are some of the challenges in developing and integrating these devices. Significant amount of research in the field of biosensors has been focused on improving the design, fabrication process and their integration with microfluidics to address these challenges. This work presents new techniques, design and systems to improve the interface between the electronic system and the biological environment. This dissertation uses CMOS circuit design to improve the reliability of these devices. Also this work addresses the challenges in designing the electronic system used for processing the output of the transducer, which converts biological signal into electronic signal.Dissertation/ThesisM.S. Electrical Engineering 201

Multiplexing pH and Temperature in a Molecular Biosensor

Robust and reliable measurements in electrochemical biosensing of molecules are crucial for personalized medicine. Electrochemical sensors based on cytochrome P450 can detect the large majority of drugs commonly used in pharmacological treatments. The same cytochrome can detect different substrates; each of them changes the electrochemical response of the enzyme in a specific manner. Our system exploits the measure of electrical potential to identify the drug type, while current measurements decode the drug concentration. Since potential and current are affected by pH and temperature, and since variations occur in the patient samples, we propose a novel design for multiplexing biosensing with pH and temperature control, which ensures more precise measurements for drugs identification and their quantification

Порівняльне вивчення впливу похідних фенотіазину та їх S-оксидів на холінестеразу за допомогою нового кінетичного спектрофотометричного методу

Aim. To develop a new kinetic spectrophotometric method for determining acetylcholinesterase (AChE) inhibitors – phenothiazine antipsychotic drugs (PhT) and their sulfoxide metabolites (S-oxides) without adding an exogenous catalyst to obtain a chromogenic agent.Materials and methods. The bases of S-oxides of promethazine (PMZ), chlorpromazine (CPM) and thioridazine (THZ) were obtained by oxidizing the corresponding PhT hydrochlorides with diperoxyadipic acid. The structure of the S-oxides of the corresponding PhT synthesized was proven by melting points, spectral characteristics (1H NMR and IR methods) and oscillopolarography results. 1H NMR spectra were recorded on a Varian XL-200 spectrometer. IR spectra were recorded within the range of 4000-400 cm–1 on a SPECORD M-80 spectrometer (Zeiss, Jena, Germany). To register polarograms, a “PO 03 CLA” oscillopolarograph with a three-electrode cell was used. The purity of S-oxides was determined by the high-performance liquid chromatography method on a Zorbax SB, C-18 (250 × 4.6) mm column. Measurements of absorbance of solutions were performed in a 1 cm cuvette on an Evolution 60S UV-Visible Thermo-Scientific Spectrophotometer (USA) (λ = 358 nm).Results and discussion. Acetylcholine (ACh) was found to mimic the activity of peroxidase; based on it, a spectrophotometric system containing ACh–H2O2–p-Ph for a sensitive and selective assessment of the AChE activity and determination of its inhibitors was developed. According to the plots of inhibition efficiency vs inhibitors concentration, the inhibiting ability of chlorpromazine, promethazine and thioridazine and their S-oxides was determined. The IC50 values of CPM, PMZ and THZ and their metabolites in relation to the AChE activity were estimated as 11 ng mL−1 (CPM) and 1.8 ng mL−1 (CPM S-oxide), 17 ng mL−1 (PMZ) and 2.5 ng mL−1 (PMZ S-oxide) and 27 ng mL−1 (THZ 2S,5S-dioxide). The results obtained indicate that S-oxides of the corresponding PhT are selective and potent inhibitors of AChE. The values of the inhibition efficiency obtained for S-oxides of PhT derivatives were an order of magnitude lower than those of the corresponding PhT derivatives.Conclusions. The spectrophotometric method proposed without the addition of other exogenous catalysts holds promise for the on-site determination of PhT antipsychotics and can be additionally used for sensory applications in areas related to environmental protection and food safety, as well as in the chemical-toxicological analysis.Мета. Розробити новий кінетико-спектрофотометричний метод визначення інгібіторів ацетилхолінестерази (АChЕ), фенотіазинових антипсихотичних засобів (PhТ) та їх сульфоксидних метаболітів (S-оксидів), без додавання екзогенного каталізатора для отримання хромогенного агента.Матеріали та методи. Основи S-оксидів прометазину, хлорпромазину та тіоридазину синтезували шляхом окиснення відповідних гідрохлоридів PhТ дипероксиадипіновою кислотою. Будову синтезованих S-оксидів відповідних PhТ доводили за температурами плавлення, спектральними характеристиками (1H ЯМР- та ІЧ-методи) та результатами осцилополярографії. Спектри 1Н ЯМР записували на спектрометрі Varian XL-200. ІЧ-спектри реєстрували в діапазоні 4000-400 см−1 на спектрометрі SPECORD M-80 (Zeiss, Jena, Німеччина). Для реєстрації полярограм використовували осцилополярограф ПО, модель 03 ЦЛА з триелектродним елементом. Чистоту S-оксидів визначали методом ВЕРХ на колонці Zorbax SB, C-18 (250 × 4,6) мм. Вимірювання поглинання випробуваних розчинів S-оксидів відповідних PhТ проводили за довжини хвилі λ = 358 нм у кюветі завтовшки 1 см на спектрофотометрі Evolution 60S UV-Visible Thermo-Scienticfic (США).Результати та їх обговорення. З’ясовано, що ацетилхолін (ACh) імітує активність пероксидази, на основі чого було розроблено спектрофотометричну систему, що містить ACh-H2O2-п-фенетидин для чутливого селективного оцінювання активності АChЕ та визначення інгібіторів ферменту. Відповідно до графіків залежності інгібувальної здатності від концентрації інгібіторів визначено інгібувальну здатність хлорпромазину, прометазину, тіоридазину та їх S-оксидів. IC50 хлорпромазину, прометазину, тіоридазину та їх метаболітів щодо активності AChE оцінено так: 11 нг мл−1 – хлорпромазин, 1,8 нг мл−1 – хлорпромазин S-оксид, 17 нг мл−1 – прометазин, 2,5 нг мл−1 – прометазин S-оксид та 27 нг мл−1 – тіоридазин 2S,5S-діоксиду. Одержані результати свідчать про те, що S-оксиди відповідних PhТ є селективними та потужними інгібіторами АChЕ. Отримані значення ефективності інгібування для S-оксидів похідних PhТ були на порядок нижчими, ніж у відповідних похідних PhТ.Висновки. Розроблена спектрофотометрична методика без додавання інших екзогенних каталізаторів має перспективи для визначення PhТ нейролептиків на місці і може бути додатково використана для сенсорних застосувань у сферах, пов’язаних із захистом навколишнього середовища та безпекою харчових продуктів, а також у хіміко-токсикологічному аналізі

Reference Compensation for Localized Surface-Plasmon Resonance Sensors

Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated for label free detection of various biological and chemical interactions. When compared to other optical sensing techniques, LSPR sensors offer label-free detection of biomolecular interactions in localized sensing volume solutions. However, these sensors also suffer from a major disadvantage – LSPR sensors remain highly susceptible to interference because they respond to both solution refractive index change and non-specific binding as well as specific binding of the target analyte. These interactions can severely compromise the measurement of the target analyte in a complex unknown media and hence limit the applicability and impact of the sensor. In spite of the extensive amount of work done in this field, there has been a clear absence of efforts to make LSPR sensors immune to interfering effects. The work presented in this document investigates, both experimentally and numerically, dual- and tri-mode LSPR sensors that utilize the multiple surface plasmon modes of gold nanostructures to distinguish target analyte from interfering bulk and non-specific binding effects. Finally, a series of biosensing experiments are performed to examine various regeneration assays for LSPR sensors built on indium tin oxide coated glass substrate

Development of Solution Blow Spun Nanofibers as Electrical and Whole Cell Biosensing Interfaces

Infectious pathogens place a huge burden on the US economy with more than $120 billion spent annually for direct and indirect costs for the treatment of infectious diseases. Rapid detection schemes continue to evolve in order to meet the demand of early diagnosis. In chronic wound infections, bacterial load is capable of impeding the healing process. Additionally, bacterial virulence production works coherently with bacterial load to produce toxins and molecules that prolongs the healing cycle. This work examines the use of nonwoven polymeric conductive and non-conductive nanofiber mats as synthetic biosensor scaffolds, drug delivery and biosensor interface constructs. A custom-made nanofiber platform was built to produce solution blow spun nanofibers of various polymer loading. Antimicrobial nanofiber mats were made with the use of an in-situ silver chemical reduction method. Ceria nanoparticles were incorporated to provide an additional antioxidative property. Conductivity properties were examined by using silver and multi-walled carbon nanotubes (MWCNT) as a filler material. SBS parameters were adjusted to analyze electrical conductivity properties. Nanofiber mats were used to detect bacteria concentrations in vitro. Protein adhesion to conductive nanofibers was studied using fluorescent antibodies and BCA assay. Anti-rabbit and streptavidin Alexa Flour 594 was used to examine the adsorption properties of SBS nanofiber mats. Enhancements were made to further improve interface design for specificity. SBS nanofiber electrodes were fabricated to serve as scaffold and detection site for spike protein detection. Bacteria virulence production was examined by the detection of pyocyanin and quorum sensing molecules. The opportunistic pathogen, Pseudomonas aeruginosa is a nosocomial iii pathogen found in immunocompromised patients with such as those with chronic wounds and cystic fibrosis. Pyocyanin is one of four quorum sensing molecules that the pathogen produces which can be detected electrochemically due to its inherent redox-active activity. SBS has been used to develop a sensing scheme to detect pyocyanin. This work also examines the use of a synthetic biosensor with a LasR based system capable of detecting homoserine lactone produced by P. aeruginosa and other common gram-negative pathogens. Genetic modifications were made to biosensor in order to replace a green, fluorescent reporter with a chromoprotein based reporter system for visual readout. Additionally, work related to community service and outreach regarding the encouragement of middle school students to pursue Science, Technology, Engineering and Math (STEM) was conducted. Results from outreach program showed an increase in the STEM interest among a group of middle school students. There was a general trend with STEM career knowledge, STEM self-efficacy and the level of interest in STEM careers and activities. Military research was also done with the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) to develop several assays for the detection of several highly infectious viruses and bacteria. Due to confidentiality, the work cannot be published in this manuscript