105 research outputs found
Biosensors for cardiac biomarkers detection: a review
The cardiovascular disease (CVD) is considered as a major threat to global health. Therefore, there is a growing demand for a range of portable, rapid and low cost biosensing devices for the detection of CVD. Biosensors can play an important role in the early diagnosis of CVD without having to rely on hospital visits where expensive and time-consuming laboratory tests are recommended. Over the last decade, many biosensors have been developed to detect a wide range of cardiac marker to reduce the costs for healthcare. One of the major challenges is to find a way of predicting the risk that an individual can suffer from CVD. There has been considerable interest in finding diagnostic and prognostic biomarkers that can be detected in blood and predict CVD risk. Of these, C-reactive protein (CRP) is the best known biomarker followed by cardiac troponin I or T (cTnI/T), myoglobin, lipoprotein-associated phospholipase A(2), interlukin-6 (IL-6), interlukin-1 (IL-1), low-density lipoprotein (LDL), myeloperoxidase (MPO) and tumor necrosis factor alpha (TNF-α) has been used to predict cardiovascular events. This review provides an overview of the available biosensor platforms for the detection of various CVD markers and considerations of future prospects for the technology are addressed
Impedimetric Sensors for Bacteria Detection
The application of electrochemical biosensors based on impedance detection has grown during the past years due to their high sensitivity and rapid response, making this technique extremely useful to detect biological interactions with biosensor platforms. This chapter is focused on the use of electrochemical impedance spectroscopy (EIS) for bacterial detection in two ways. On one hand, bacteria presence may be determined by the detection of metabolites produced by bacterial growth involving the media conductivity changes. On the other hand, faster and more selective bacterial detection may be achieved by the immobilization of bacteria on a sensor surface using biorecognition elements (antibodies, antimicrobial peptides, aptamers, etc.) and registering changes produced in the charge transfer resistance (faradic process) or interfacial impedance (nonfaradic process). Here we discuss different types of impedimetric biosensors for microbiological applications, making stress on their most important parameters, such as detection limits, detection times, selectivity, and sensitivity. The aim of the paper was to give a critical review of recent publications in the field and mark the future trends
Antimicrobial peptides: Powerful biorecognition elements to detect bacteria in biosensing technologies
Bacterial infections represent a serious threat in modern medicine. In particular, biofilm treatment in clinical settings is challenging, as biofilms are very resistant to conventional antibiotic therapy and may spread infecting other tissues. To address this problem, biosensing technologies are emerging as a powerful solution to detect and identify bacterial pathogens at the very early stages of the infection, thus allowing rapid and effective treatments before biofilms are formed. Biosensors typically consist of two main parts, a biorecognition moiety that interacts with the target (i.e., bacteria) and a platform that transduces such interaction into a measurable signal. This review will focus on the development of impedimetric biosensors using antimicrobial peptides (AMPs) as biorecognition elements. AMPs belong to the innate immune system of living organisms and are very effective in interacting with bacterial membranes. They offer unique advantages compared to other classical bioreceptor molecules such as enzymes or antibodies. Moreover, impedance-based sensors allow the development of label-free, rapid, sensitive, specific and cost-effective sensing platforms. In summary, AMPs and impedimetric transducers combine excellent properties to produce robust biosensors for the early detection of bacterial infectionsPeer ReviewedPostprint (published version
Biosensor Platforms for Rapid Detection of <i>E. coli</i> Bacteria
Risks of contamination with the well-known food pathogen Escherichia coli are increasing over the years. Therefore, rapid and portable technologies using different types of advanced devices named biosensors with various transduction capabilities (electrochemical, optical, or acoustic) were developed and seem to offer the most elegant solutions for research communities and final users-humans. Thus, integration of microfluidic biochips/biosensors into smartphones offer the real-time detection of any infection with E. coli, helping doctors in proceeding immediately with the clinical treatment. The present chapter will discuss about the analytical performances of biosensors and microfluidics such as selection of substrates, type of (bio)functionalization, low limit of detection, specificity, and response time for monitoring different E. coli strains. Thus, it is possible to rapidly identify (30–90 s) very low concentrations of E. coli (101 CFU/mL) down to a single bacterium in real samples (water, urine, milk, beef-meat) by simple integration of an angle scatter method and microfluidic-cellulosic pads (μPAD) loaded with micro-/nanoparticles functionalized with either polyclonal anti E. coli antibodies or with DNA strains into a portable device—a smartphone. Such biosensor configuration can also be used for the detection of other types of microorganisms with potential human and animal health concerns
Establishment of surface functionalization methods for spore-based biosensors and implementation into sensor technologies for aseptic food processing
Aseptic processing has become a popular technology to increase the shelf-life of packaged products and to provide non-contaminated goods to the consumers. In 2017, the global aseptic market was evaluated to be about 39.5 billion USD. Many liquid food products, like juice or milk, are delivered to customers every day by employing aseptic filling machines. They can operate around 12,000 ready-packaged products per hour (e.g., Pure-Pak® Aseptic Filling Line E-PS120A). However, they need to be routinely validated to guarantee contamination-free goods. The state-of-the-art methods to validate such machines are by means of microbiological analyses, where bacterial spores are used as test organisms because of their high resistance against several sterilants (e.g., gaseous hydrogen peroxide). The main disadvantage of the aforementioned tests is time: it takes at least 36-48 hours to get the results, i.e., the products cannot be delivered to customers without the validation certificate. Just in this example, in 36 hours, 432,000 products would be on hold for dispatchment; if more machines are evaluated, this number would linearly grow and at the end, the costs (only for waiting for the results) would be considerably high. For this reason, it is very valuable to develop new sensor technologies to overcome this issue. Therefore, the main focus of this thesis is on the further development of a spore-based biosensor; this sensor can determine the viability of spores after being sterilized with hydrogen peroxide. However, the immobilization strategy as well as its implementation on sensing elements and a more detailed investigation regarding its operating principle are missing.
In this thesis, an immobilization strategy is developed to withstand harsh conditions (high temperatures, oxidizing environment) for spore-based biosensors applied in aseptic processing. A systematic investigation of the surface functionalization’s effect (e.g., hydroxylation) on sensors (e.g., electrolyte-insulator semiconductor (EIS) chips) is presented. Later on, organosilanes are analyzed for the immobilization of bacterial spores on different sensor surfaces. The electrical properties of the immobilization layer are studied as well as its resistance to a sterilization process with gaseous hydrogen peroxide. In addition, a sensor array consisting of a calorimetric gas sensor and a spore-based biosensor to measure hydrogen peroxide concentrations and the spores’ viability at the same time is proposed to evaluate the efficacy of sterilization processes
Electrochemically controlled patterning for biosensor arrays.
Existe una demanda creciente de dispositivos de análisis multianalito, con aplicaciones
potenciales en los campos de la biomedicina y biotecnología, así como en el ámbito
industrial y ambiental. Para el desarrollo de estos dispositivos resulta esencial un buen
control espacial durante la etapa de inmovilización de las biomoléculas de interés; cada
una de ellas debe ser depositada de forma precisa sobre la superficie del sensor (por
ejemplo, un transductor amperométrico), evitando solapamientos que puedan
comprometer la especificidad del sistema.
El objetivo de esta tesis es desarrollar diferentes métodos de patterning para la
inmovilización selectiva de biomoléculas. El primer método consiste en la
electrodeposición selectiva de nanopartículas de oro biofuncionalizadas para el
desarrollo de biochips. Se trata de un método de patterning controlado
electroquímicamente, en el que las nanopartículas de oro se modifican en primer lugar
recubriéndolas con diversos enzimas y a continuación se electrodepositan
selectivamente sobre la superficie de un electrodo. Como parte de esta metodología, se
prepararon nanopartículas de oro biofuncionalizadas utilizando tres estrategias
diferentes: a través del enlace dativo oro-tiol, por adsorción directa o mediante
interacción electrostática siguiendo la técnica layer-by-layer (capa por capa). Para la
funcionalización de las nanopartículas de oro se emplearon distintas biomoléculas,
como los enzimas peroxidasa de rábano (HRP), glucosa oxidasa (GOX) y albúmina de
suero bovino (BSA), y finalmente oligonucleótidos modificados con moléculas
fluorescentes y grupos tiol. Las nanopartículas biofuncionalizadas fueron caracterizadas
mediante técnicas de espectroscopía UV-visible, microscopía electrónica de transmisión
(TEM) y medida del potencial zeta. Mediante espectroscopía UV-visible se observó un
pico de resonancia de plasmón característico de las nanopartículas modificadas,
relacionado con la estabilidad de la preparación. La medida del potencial zeta permitió
la caracterización de las nanopartículas de oro modificadas capa por capa con polímero
redox y enzimas. También se estudiaron los cambios en el potencial zeta de
nanopartículas modificadas con BSA a distintos valores de pH. Tras la preparación de
las partículas biofuncionalizadas, se llevaron a cabo estudios fundamentales de
electrodeposición de nanopartículas de oro modificadas con BSA y un polímero redox,
con el fin de analizar el efecto de varios parámetros: potencial aplicado, tiempo de deposición, distancia entre los electrodos, superficie del electrodo auxiliar y pH del
medio. Para estudiar el comportamiento electrocatalítico de las nanopartículas
modificadas una vez electrodepositadas, se llevaron a cabo experimentos utilizando
coloides de oro modificados con HRP y GOX. A continuación se empleó esta
metodología para el desarrollo de biochips, utilizando dos configuraciones diferentes.
En la primera, se electrodepositaron nanopartículas de oro funcionalizadas con GOX y
HRP y modificadas con un polímero redox sobre la superficie de un chip de electrodos
interdigitados (IDE), consiguiendo eliminar por completo las repuestas no específicas.
En la segunda configuración, las partículas se modificaron con una capa adicional de
polímero redox, comprobando de nuevo la ausencia total de respuestas no específicas
después de la electrodeposición. Esta método de patterning es genérico y puede
utilizarse para la producción de diversos biochips.
El segundo método de patterning también está basado en el control electroquímico, y
consiste en la modificación de los electrodos con monocapas autoensambladas
electroactivas cuya funcionalidad es modulable en función del potencial aplicado. En
esta metodología, la monocapa electroactiva contiene grupos acetal que pueden ser
desprotegidos selectivamente mediante la aplicación de un potencial en zonas
específicas de la superficie del electrodo. De esta manera quedan expuestos en la
superficie grupos aldehído activos, que pueden ser fácilmente conjugados con aminas
primarias presentes en las biomoléculas de interés. Los enzimas GOX y HRP se usaron
como proteínas modelo para comprobar la versatilidad de esta técnica. Su aplicabilidad
para la fabricación de biochips se demostró con medidas amperométricas y medidas en
tiempo real mediante resonancia de plasmón de superficie combinado con
electroquímica (eSPR).
La tercera metodología es también un sistema de patterning controlado
electroquímicamente, pero en este caso se utiliza la inmovilización del 4,4-bipiridil
como base para la creación de biochips. Se sintetizaron moléculas de 4,4-bipiridil
funcionalizadas con grupos carboxílicos, que fueron caracterizadas electroquímicamente
y a continuación conjugadas con las biomoléculas de interés para la creación de
biochips. La selectividad de estos sistemas se demostró colorimétricamente,
obteniéndose niveles mínimos de respuesta inespecífica.
Por último, el cuarto de los métodos de patterning desarrollados está basado en la
técnica de fotolitografía. Los enzimas glucosa oxidasa y sarcosina oxidasa se
depositaron selectivamente junto con un polímero redox sobre la superficie de
electrodos interdigitados utilizando un proceso de lift off, consiguiendo eliminar por
completo las señales cruzadas o cross-talk. Como parte de esta metodología se
optimizaron varios procedimientos de inmovilización de las biomoléculas, con el fin de
seleccionar la estrategia más adecuada. También se llevaron a cabo ensayos con
diferentes reactivos para eliminar la adsorción inespecífica. Finalmente, el sistema
optimizado fue aplicado sobre IDEs fabricados mediante fotolitografía. Los sensores de
glucosa y sarcosina respondieron de forma selectiva a sus respectivos sustratos, con
ausencia total de cross-talk.
La presente tesis está estructurada en 7 capítulos. En el Capítulo I se exponen las bases
del desarrollo de biochips, métodos de patterning con control electroquímico, otros
métodos de patterning selectivo y las técnicas de fotolitografía, así como un resumen de
la tesis. El Capítulo 2 y 3 describe la síntesis de coloides de oro, la modificación con
biomoléculas, los estudios de estabilidad y los estudios fundamentales de
electrodeposición de las nanopartículas de oro modificadas sobre la superficie de los
electrodos. En el Capítulo 4 se muestra la aplicación de la electrodeposición de
nanopartículas de oro biofuncionalizadas para la creación de biochips. El Capítulo 5
describe la inmovilización selectiva de biomoléculas mediante la desprotección
electroquímica de monocapas autoensambladas electroactivas. En el Capítulo 6 se
muestra la síntesis, caracterización e inmovilización selectiva de derivados de 4,4-
bipiridil funcionalizados con HRP. El Capítulo 7 describe el patterning selectivo en la
escala micrométrica de dos oxidasas sobre un chip de electrodos interdigitados mediante
fotolitografía. Finalmente, el Capítulo 8 resume las conclusiones y el trabajo futuro.There is an increasing demand of multianalyte sensing devices having potential
applications in biomedical, biotechnological, industrial and environmental fields. A
good spatial control during biomolecule deposition step is strictly necessary; each
biomolecule has to be precisely deposited on the surface of the relevant sensor (eg., an
amperometric transducer), avoiding mixing that can compromise the biosensor
specificity.
The aim of this thesis is to develop different patterning methods for the selective
immobilization of biomolecules. The first method is selective electrodeposition of
biofunctionalized Au nanoparticles for biosensor arrays. This is an electrochemically
controlled patterning method where the Au nanoparticles modified by the enzymes
initially and later the enzyme modified Au nanoparticles were electrodeposited
selectively on the electrode surface. As a part of this methodology, initially
biofunctionalized Au nanoparticles were prepared using three different approcahes. One
is Au-thiol dative bonding, the second is direct adsorption and finally electrostatic layerby-
layer approach. Different biomolecules like horse radish peroxidase(HRP), glucose
oxidase (GOX), bovine serum albumin(BSA), and finally fluorescence labelled
oilgonucleotide thiols were used to attch to the Au nanoparticles. Biofunctionalized Au
nanoparticles were characterized by different techniques like zeta sizer, UV-Vis
spectroscopy, transmission electron microscopy (TEM). UV-Vis spectroscopy showed
the successfull modification of Au nanoparticles with a characterstic surface plasmon
peak related to the stability. By using zeta sizer, layer-by-layer modification of the Au
nanoparticles with redox polymer and enzymes were characterized successfully.
Changes of the Au nanoparticles modified with BSA was characterised at different pH s
by using the zeta sizer. After the preparation of biofunctionalized particles, some
fundamental studies were done with electrodeposition of Au nanoparticles modified
with medically important BSA, redox polymer to see how different parameters like
potential, time of deposition, interelectrode distance, counter electrode sized, pH, effect
the electrodeposition. As a part of these fundamental studies Au colloids modified with
HRP and GOX were deposited for studying the electrocalaytic behaviour of the
enzymes on the Au nanoparticles after electrodeposition. Later this methodology was
applied for creating biosensor arrays by using two different approaches. In the first
approach, GOX and HRP functionalized redox polymer modified Au nanoparticles were electrodeposited successfully on an interdigitated electrode (IDE) array with complete
absence of non-specific response. In the second approach the particles were modified
with an extra redox polymer layer and proved that there is complete absence of nonspecific
response after electrodeposition. Moreover, this patterning methodology is
generic and can be used for production of different biochips.
The second method is another electrochemically controlled patterning method where
the electrodes were immobilized with self assembled monolayers with electroactive
functionalities which can be tunable with potentials. In this methodology, electroactive
self-assembled monolayer contains an active ligand aldehyde which can be readily
conjugated to the primary amine group of the biomolecule is protected in the form of
acetal. Later when a active potential was applied to the underlying electrode surface, the
acetal functionality is deprotected to reveal the aldehyde functionality which was further
conjugated to the biomolecule. Two enzymes GOX, HRP were used as model proteins
to prove the versatility of this technique. Amperometric as well as real time
measurements proved the selective applicability of this technique for creation of
biosensor arrays.
The third methodology is also an electrochemically controlled patterning methodology
where the special advantage of the electrochemically-controlled immobilization of the
4,4-bipyridyl was taken as base for the creation of biosensor arrays. In this
methodology, carboxylic acid functionalised 4,4, bipyridyl molecules were synthesized
and characterized by electrochemistry. Later the biomolecules were conjugated to these
special molecules for the creation of sensor arrays. Proof of selectivity was shown using
colourimetrically with minimal non-specific response.
Finally in the fourth method which is based on the photolithography technique, two
different oxidases GOX & SOX were patterned along with redox polymer selectively on
an IDE array using the lift off process with complete absence of cross-talk. As a part of
this methodology, different immobilization methods were optimized initially for
checking the best optimisation strategy. Later different reagents were tried to optimise
the best reagent that prevents the non-specific adsorption. Later this optimised system
was applied on the pholithographically created IDE array. Sarcosine and glucose
sensors responded selectively to their substrates with complete absence of cross talk. This thesis is structured in 7 chapters. Chapter 1 establishes to basics of the biosensor
arrays, electrochemically controlled patterning methods, other selectively patterned
methods, photolithography and summary of this thesis. Chapter 2 describes about the
gold colloid synthesis, modification with the biomolecules, stability studies. Chapter 3
decribes fundamental studies of the electrodeposition of the functionalised Au
nanoparticles on the electrode surface. Chapter 4 describes the application of the
electrodeposition of the protein functionalised Au nanoparticles for the creation of
biosensor arrays. Chapter 5 describes the selective immobilization of biomolecules
through electrochemical deprotection of electroactive self-assembled monolayers.
Chapter 6 describes the synthesis, characterization and selective immobilization of HRP
functionalized 4,4-bipyridyl derivatives. Chapter 7 describes the selective microscale
protein patterning of two oxidases on an IDE array through photolithography. Finally
chapter 8 summarizes the conclusions and the future work
Nanomaterials for Healthcare Biosensing Applications
In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing
- …