Incorporating Fluorescent Nanomaterials in Organically Modified Sol-Gel Materials – Creating Single Composite Optical pH Sensors

10.26434/chemrxiv.13606715.v1 ◽

2021 ◽

Author(s):

David Bartos ◽

Morten Rewers ◽

Lu Wang ◽

Thomas Just Sørensen

Keyword(s):

Optical Sensors ◽

Optical Sensor ◽

Sol Gel ◽

Ph Sensor ◽

High Signal ◽

Sensor Material ◽

Digital World ◽

Organically Modified ◽

Optical Ph Sensors ◽

Sensor Materials

<br><br>Optical sensors hold the promise of providing the coupling between the tangible and the digital world that we are currently experiencing with physical sensors. The core of optical sensor development lies in materials development, where specific requirements of opposing physicochemical properties create a significant obstacle. The sensor material must provide dye retention, while ensuring porosity for analyte transport. The sensor material must provide hydrophobic pockets for dyes to ensure high signal intensity, while remaining fully hydrophobic to measure in water. We have previously reported optical sensors, where we compromised on sensor manufacturing by using a double-layer composite. Here, we report a composite organically modified sol-gel (ORMOSIL) polymer, where polystyrene (PS) nanoparticles (NPs) have been incorporated. This allows all the opposing requirements on optical sensor materials to be fulfilled, and by introducing a hydrophobic reference dye in the fully hydrophobic compartments of the sensor material we show that we can incorporate any hydrophobic fluorophore in this material, even those which are suffering from quenching in water. In this work, PS NPs with 1,13-dimethoxyquinacridinium (DMQA) were immobilized in a composite sol-gel material with pH responsive diazaoxatriangulenium (DAOTA) dyes prior to curing. The multicomponent sensor composite was cured on a polycarbonate hemiwicking substrate, and the resulting fluorescence intensity ratiometric optical pH sensor was shown to have excellent performance. We expect that this type of composite sensor materials will allow the creation of next generation industrial chemosensors.<br><br>

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Incorporating Fluorescent Nanomaterials in Organically Modified Sol-Gel Materials – Creating Single Composite Optical pH Sensors

Sensors & Diagnostics ◽

10.1039/d1sd00002k ◽

2022 ◽

Author(s):

David Bartos ◽

Morten Rewers ◽

Lu Wang ◽

Thomas Just Sørensen

Keyword(s):

Optical Sensors ◽

Sol Gel ◽

Ph Sensors ◽

Sensor Development ◽

The Core ◽

Digital World ◽

Physical Sensors ◽

Organically Modified ◽

Optical Ph Sensors ◽

Fluorescent Nanomaterials

Optical sensors hold the promise of providing the coupling between the tangible and the digital world that we are currently experiencing with physical sensors. The core of optical sensor development...

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Microstructural characterization of sol-gel coating on PET films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172164 ◽

1994 ◽

Vol 52 ◽

pp. 886-887

Author(s):

R. T. Chen ◽

R.A. Norwood

Keyword(s):

Ion Beam ◽

Sol Gel ◽

Industrial Applications ◽

Hard Coatings ◽

Nanometer Scale ◽

Ion Beam Sputtering ◽

Process Technology ◽

Refractive Index Measurement ◽

Organically Modified ◽

Pet Films

Sol-gel processing has been used to control the structure of a material on a nanometer scale in preparing advanced ceramics and glasses. Film coating using the sol-gel process was also found to be a viable process technology in applications such as optical, porous, antireflection and hard coatings. In this study, organically modified silicate (Ormosil) coatings are applied to PET films for various industrial applications. Sol-gel materials are known to exhibit nanometer scale structures which havepreviously been characterized by small-angle X-ray scattering (SAXS), neutron scattering and light scattering. Imaging of the ultrafine sol-gel structures has also been performed using an ultrahigh resolution replica/TEM technique. The objective of this study was to evaluate the ultrafine structures inthe sol gel coatings using a direct imaging technique: atomic force microscopy (AFM). In addition, correlation of microstructures with processing parameters, coating density and other physical properties will be discussed.The materials evaluated are organically modified silicate coatings on PET film substrates. Refractive index measurement by the prism coupling method was used to assess density of the sol-gel coating.AFM imaging was performed on a Nanoscope III AFM (by Digital Instruments) using constant force mode. Solgel coating samples coated with a thin layer of Ft (by ion beam sputtering) were also examined by STM in order to confirm the structures observed in the contact type AFM. In addition, to compare the previous results, sol-gel powder samples were also prepared by ultrasonication followed by Pt/Au shadowing and examined using a JEOL 100CX TEM.

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Hybrid Micro-Optical Sensors via Sol-Gel Soft Lithography

MRS Proceedings ◽

10.1557/proc-628-cc9.3 ◽

2000 ◽

Vol 628 ◽

Cited By ~ 1

Author(s):

Mark A. Clarner ◽

Michael J. Lochhead

Keyword(s):

Optical Sensors ◽

Soft Lithography ◽

Sol Gel ◽

Silica Gels ◽

Ph Sensing ◽

Ambient Conditions ◽

Sensor Applications ◽

Patterned Structures ◽

Biological Functionality ◽

Indicator Dyes

ABSTRACTOrganically modified silica gels and dye-doped silica gels have been patterned into micrometer-scale structures on a substrate using micro molding in capillaries (MIMIC). This approach is from a class of elastomeric stamping and molding techniques collectively known as soft lithography. Soft lithography and sol-gel processing share attractive features in that they are relatively benign processes performed at ambient conditions, which makes both techniques compatible with a wide variety of organic molecules, molecular assemblies, and biomolecules. The combination of sol-gel and soft lithography, therefore, holds enormous promise as a tool for microfabrication of materials with optical, chemical, or biological functionality that are not readily patterned with conventional methods. This paper describes our investigation of micro-patterned organic-inorganic hybrid materials containing indicator dyes for microfluidic sensor applications. Reversible colorimetric pH sensing via entrapped reagents is demonstrated in a prototype microfluidic sensor element. Patterned structures range from one to tens of micrometers in cross-section and are up to centimeters in length. Fundamental chemical processing issues associated with mold filling, cracking and sensor stability are discussed.

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Tantalum Oxide Nanoparticles as Versatile Contrast Agents for X-ray Computed Tomography

10.26434/chemrxiv.11845572.v1 ◽

2020 ◽

Author(s):

Shatadru Chakravarty ◽

Jeremy Hix ◽

Kaitlyn Wieweora ◽

Maximilian Volk ◽

Elizabeth Kenyon ◽

...

Keyword(s):

Computed Tomography ◽

Contrast Agents ◽

Mesoporous Silica Nanoparticles ◽

Sol Gel ◽

Tantalum Oxide ◽

High Signal ◽

Drug Delivery Vehicles ◽

X Ray Computed

Here we describe the synthesis, characterization and in vitro and in vivo performance of a series of tantalum oxide (TaOx) based nanoparticles (NPs) for computed tomography (CT). Five distinct versions of 9-12 nm diameter silane coated TaOx nanocrystals (NCs) were fabricated by a sol-gel method with varying degrees of hydrophilicity and with or without fluorescence, with the highest reported Ta content to date (78%). Highly hydrophilic NCs were left bare and were evaluated in vivo in mice for micro-CT of full body vasculature, where following intravenous injection, TaOx NCs demonstrate high CT contrast, circulation in blood for ~ 3 h, and eventual accumulation in RES organs; and following injection locally in the mammary gland, where the full ductal tree structure can be clearly delineated. Partially hydrophilic NCs were encapsulated within mesoporous silica nanoparticles (MSNPs; TaOx@MSNPs) and hydrophobic NCs were encapsulated within poly(lactic-co-glycolic acid) (PLGA; TaOx@PLGA) NPs, serving as potential CT-imagable drug delivery vehicles. Bolus intramuscular injections of TaOx@PLGA NPs and TaOx@MSNPs to mimic the accumulation of NPs at a tumor site produce high signal enhancement in mice. In vitro studies on bare NCs and formuated NPs demonstrate high cytocompatibility and low dissolution of TaOx. This work solidifies that TaOx-based NPs are versatile contrast agents for CT.

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Silica and Silica–Titania Xerogels Doped with Iron(III) for Total Antioxidant Capacity Determination

Materials ◽

10.3390/ma14082019 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2019

Author(s):

Maria A. Morosanova ◽

Ksenia V. Chaikun ◽

Elena I. Morosanova

Keyword(s):

Antioxidant Capacity ◽

Surface Area ◽

Total Antioxidant Capacity ◽

Solid Phase ◽

Bet Surface Area ◽

Sensor Material ◽

Total Antioxidant ◽

Sensor Materials ◽

Ascorbic Acids ◽

Capacity Determination

In order to design a sensor material for total antioxidant capacity determination we have prepared silica and silica–titania xerogels doped with iron(III) and modified with 1,10-phenanthroline. Titanium(IV) tetraethoxyde content in the precursors (titanium(IV) tetraethoxyde and tetraethyl orthosilicate) mixtures has been varied from 0 to 12.5% vol. Iron(III) concentrations in sol has been varied from 1 to 100 mM. The increase of titanium(IV) content has led to a decrease in BET surface area and average pore diameter and an increase of micropore surface area and volume, which has resulted in better iron(III) retention in the xerogels. Iron(III), immobilized in the xerogel matrix, retains its ability to form complexes with 1,10-phenanthroline and to be reduced to iron(II). Static capacities for 1,10-phenanthroline have been determined for all the iron(III) doped xerogels (0.207 mmol/g–0.239 mmol/g) and they are not dependent on the iron(III) content. Sensor materials—xerogels doped with iron(III) and modified with 1,10-phenanthroline—have been used for antioxidants (catechol, gallic and ascorbic acids, and sulphite) solid phase spectrophotometric determination. Limits of detection for catechol, gallic and ascorbic acids, and sulphite equal 7.8 × 10−6 M, 5.4 × 10−6 M, 1.2 × 10−5 M, and 3.1 × 10−4 M, respectively. The increase of titanium(IV) content in sensor material has led to an increase of the reaction rate and the sensitivity of determination. Proposed sensor materials have been applied for total antioxidant capacity (in gallic acid equivalents) determination in soft beverages, have demonstrated high stability, and can be stored up to 6 months at room temperature.

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Ex-Vivo Measurement of the pH in Aqueous Humor Samples by a Tapered Fiber-Optic Sensor

Sensors ◽

10.3390/s21155075 ◽

2021 ◽

Vol 21 (15) ◽

pp. 5075

Author(s):

Ondřej Podrazký ◽

Jan Mrázek ◽

Jana Proboštová ◽

Soňa Vytykáčová ◽

Ivan Kašík ◽

...

Keyword(s):

Cataract Surgery ◽

Aqueous Humor ◽

Fiber Optic ◽

Ex Vivo ◽

Sol Gel ◽

Ph Sensor ◽

Fiber Optic Sensor ◽

Optic Sensor ◽

Tapered Optical Fiber ◽

Practical Demonstration

A practical demonstration of pH measurement in real biological samples with an in-house developed fiber-optic pH sensor system is presented. The sensor uses 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) fluorescent dye as the opto-chemical transducer. The dye is immobilized in a hybrid sol-gel matrix at the tip of a tapered optical fiber. We used 405 nm and 450 nm laser diodes for the dye excitation and a photomultiplier tube as a detector. The sensor was used for the measurement of pH in human aqueous humor samples during cataract surgery. Two groups of patients were tested, one underwent conventional phacoemulsification removal of the lens while the other was subjected to femtosecond laser assisted cataract surgery (FLACS). The precision of the measurement was ±0.04 pH units. The average pH of the aqueous humor of patients subjected to FLACS and those subjected to phacoemulsification were 7.24 ± 0.17 and 7.31 ± 0.20 respectively.

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Sol-Gel Optical Sensors for Glutamate

MRS Proceedings ◽

10.1557/proc-662-oo2.2 ◽

2000 ◽

Vol 662 ◽

Author(s):

Jenna L. Rickus ◽

Esther Lan ◽

Allan J. Tobin ◽

Jeffery I. Zink ◽

Bruce Dunn

Keyword(s):

Optical Sensors ◽

Sol Gel ◽

Kinetic Studies ◽

Excitatory Neurotransmitter ◽

Nadh Fluorescence ◽

Millisecond Time Scale ◽

Temporal And Spatial ◽

Sensor Detection ◽

The Brain ◽

Amino Acid Glutamate

AbstractThe amino acid glutamate is the major excitatory neurotransmitter used in the nervous system for interneuronal communication. It is used throughout the brain by various neuronal pathways including those involved in learning and memory, locomotion, and sensory perception. Because glutamate is released from neurons on a millisecond time scale into sub-micrometer spaces, the development of a glutamate biosensor with high temporal and spatial resolution is of great interest for the study of neurological function and disease. Here, we demonstrate the feasibility of an optical glutamate sensor based on the sol-gel encapsulation of the enzyme glutamate dehydrogenase (GDH). GDH catalyses the oxidative deamination of glutamate and the reduction of NAD+ to NADH. NADH fluorescence is the basis of the sensor detection. Thermodynamic and kinetic studies show that GDH remains active in the sol-gel matrix and that the reaction rate is correlated to the glutamate concentration.

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