Utilizing a Paper-Based Platform for Oilfield Applications: Time-Resolved Fluorescence Imaging and Detection of Interwell Chemical Tracers.

Chemical tracers are indispensable tools for enhancing reservoir characterization and optimizing production processes in the oil and gas industry. Particularly, interwell water tracers provide key data for efficient water flood management and the improvement of production rates. However, the analysis of these water tracers within reservoir fluids is challenging, requiring laborious separation and extraction steps that often rely on complex instruments and skilled operators. Real-time analysis is especially problematic in remote areas with limited access to well-equipped laboratories. To address these challenges, we introduce a paper-based platform for the time-resolved fluorescence detection of dipicolinic acid (DPA) tracers complexed with terbium ion (Tb3+). Our innovation is driven by the need to simplify tracer analysis, make it portable, and enhance accessibility for oilfield applications. By leveraging the unique properties of cyclen-based macrocyclic ligands, we have achieved the stable and sensitive immobilization of Tb3+ on quartz microfilter paper, eliminating the need for extensive laboratory-based procedures. We achieve the stable and sensitive immobilization of Tb3+ on quartz microfilter paper by leveraging the unique properties of cyclen-based macrocyclic ligands. This innovation enables the formation of highly fluorescent, oil-blind, and optically detectable DPA-Tb3+ complexes at the paper surface. We visualize and capture these fluorescence signals using an intensified charge-coupled device camera via time gating, effectively suppressing undesirable fluorescence originating from crude oil. The quantification of DPA concentrations is achievable down to 158 ppb (9.45 × 10-7 M), as confirmed through time-resolved fluorescence microplate reader measurements. We also demonstrate the practicality of our technology by detecting DPA tracers in the presence of crude oil contamination, a common challenge encountered in oil production wells.

Terahertz imaging for non-destructive porosity measurements of carbonate rocks.

Within the petrochemical industry, accurate measurement of microporosity and its distribution within core samples, particularly those from carbonate reservoirs, has garnered intense interest because studies have suggested that following primary and secondary depletion, a majority of the residual and bypassed oil may reside in these porosities. Ideally, the microporosity and its distribution would be determined accurately, quickly, and efficiently. Imaging techniques are commonly used to characterize the porosity and pores but accurate microporosity characterization can be challenging due to resolution and scale limitations. To this end, this study describes the development and verification of a novel method to characterize microporosity in carbonate rocks using terahertz time-domain spectroscopy and exploiting the high signal absorption due to water at these high frequencies. This new method is able to measure microporosity and the results agree well with other bulk measurements and produce microporosity maps which is not possible with many bulk characterization or imaging methods. These microporosity maps show the spatial variation of micropores within a sample and offers insights into the heterogeneity of reservoir materials.

Continuous Multistage Synthesis and Functionalization of Sub-100 nm Silica Nanoparticles in 3D-Printed Continuous Stirred-Tank Reactor Cascades.

The controlled and continuous production of nanoparticles (NPs) with functionalized surfaces remains a technological challenge. We present a multistage synthetic platform, consisting of 3D-printed miniature continuous stirred-tank reactor (CSTR) cascades, for the continuous synthesis and functionalization of SiO2 NPs. The use of the CSTR platform provides ideal and rapid mixing of precursor solutions, precise injection of additional reagents for multistep reactions, and facile operation when using viscous solutions and handling of syntheses with longer reaction times. To exemplify the use of such custom-designed CSTR cascades, amine- and carbohydrate-functionalized SiO2 NPs are chosen as model reaction systems. In particular, the intensified flow reactor units allowed for the reproducible formation of SiO2 NPs with diameters less than 100 nm and narrow size distributions (3-8%). Most importantly, by assembling various 3D-printed CSTR cascades, we synthesized gluconolactone-capped polyethylenimine-modified silica NPs in a fully continuous manner. The inherent control over NP surface charge, reactor scalability, and the significant shortening of processing times (less than 10 min) compared to batch methodologies (several days) strongly indicate the ability of the reactor technology to accelerate continuous nanomanufacturing. In general, it provides a simple route for the reproducible preparation of functionalized NPs, thus expanding the gamut of flow reactors for material synthesis.

Predicting Stability Constants for Terbium(III) Complexes with Dipicolinic Acid and 4-Substituted Dipicolinic Acid Analogues using Density Functional Theory.

The relative stability constants of Tb(III) complexes exhibiting binding to a series of 4-substituted analogues of dipicolinic acid (2,6-pyridinedicarboxylic acid) (DPA) were calculated using density functional theory (DFT) with the standard thermodynamic cycle. DFT calculations showed that the strengths of the stability constants were modified by the substituents in the following (decreasing) order: -NH2 > -OH ∼ -CH2OH > -imidazole ∼ -Cl ∼ -Br ∼ -H > -F > -I, with the differences among them falling within one to two log units except for -NH2. Through population and structural analysis, we observed that the -NH2, -OH, -CH2OH, and halide substituents can donate electrons via resonance effect to the pyridine ring of DPA while inductively withdrawing electrons with different strengths, thus resulting in the different binding strengths of the 4-substituted DPAs to the Tb(III) ions. We believe that these observations possess utility not only in the ongoing development of luminescent probes for bioanalytical studies but also for more recent cross-industrial efforts to enhance reservoir surveillance capabilities using chemical tracers within the oil and gas sector.

Intracellular delivery of core-shell fluorescent silica nanoparticles.

Highly fluorescent core-shell silica nanoparticles made by the modified Stöber process (C dots) are promising as tools for sensing and imaging subcellular agents and structures but will only be useful if they can be easily delivered to the cytoplasm of the subject cells. This work shows that C dots can be electrostatically coated with cationic polymers, changing their surface charge and enabling them to escape from endosomes and enter the cytoplasm and nucleus. As an example of cellular delivery, we demonstrate that these particles can also be complexed with DNA and mediate and trace DNA delivery and gene expression.

Pyrolyzable Nanoparticle Tracers for Environmental Interrogation and Monitoring.

Environmental tracing applications require materials that can be detected in complex fluids composed of multiple phases and contaminants. Moreover, large libraries of tracers are necessary in order to mitigate memory effects and to deploy multiple tracers simultaneously in complex oil fields. Herein, we disclose a novel approach based on the thermal decomposition of polymeric nanoparticles comprised of styrenic and methacrylic monomers. Polymeric nanoparticles derived from these monomers cleanly decompose into their constituent monomers at elevated temperatures, thereby maximizing atom economy wherein the entire nanoparticle mass contributes to the generation of detectable units. A total of ten unique single monomer particles and three dual-monomer particles were synthesized using semicontinuous monomer starved addition polymerization. The pyrolysis gas chromatography-flame ionization detection/mass spectrometry (GC-FID/MS) behavior of these particles was studied using high-pressure mass spectrometry. The programmable nature of our methodology permits simultaneous removal of contaminants and subsequent identification and quantification in a single analytical step.

Hydration Repulsion between Carbohydrate Surfaces Mediated by Temperature and Specific Ions.

Stabilizing colloids or nanoparticles in solution involves a fine balance between surface charges, steric repulsion of coating molecules, and hydration forces against van der Waals attractions. At high temperature and electrolyte concentrations, the colloidal stability of suspensions usually decreases rapidly. Here, we report a new experimental and simulation discovery that the polysaccharide (dextran) coated nanoparticles show ion-specific colloidal stability at high temperature, where we observed enhanced colloidal stability of nanoparticles in CaCl2 solution but rapid nanoparticle-nanoparticle aggregation in MgCl2 solution. The microscopic mechanism was unveiled in atomistic simulations. The presence of surface bound Ca(2+) ions increases the carbohydrate hydration and induces strongly polarized repulsive water structures beyond at least three hydration shells which is farther-reaching than previously assumed. We believe leveraging the binding of strongly hydrated ions to macromolecular surfaces represents a new paradigm in achieving absolute hydration and colloidal stability for a variety of materials, particularly under extreme conditions.

A plug-and-play ratiometric pH-sensing nanoprobe for high-throughput investigation of endosomal escape.

An important aspect in the design of nanomaterials for delivery is an understanding of its uptake and ultimate release to the cytosol of target cells. Real-time chemical sensing using a nanoparticle-based platform affords exquisite insight into the trafficking of materials and their cargo into cells. This versatile and tunable technology provides a powerful tool to probe the mechanism of cellular entry and cytosolic delivery of a variety of materials, allowing for a simple and convenient means to screen materials towards efficient delivery of therapeutics such as nucleic acids.

Tracking mesenchymal stem cell tumor-homing using fluorescent silica nanoparticles.

Stem cell tracking can reveal the underlying biological processes of stem-cell-based therapies such as the migration and biodistribution of human mesenchymal stem cells (hMSCs) in cancer therapy. Nanoparticle-based contrast agents offer unprecedented opportunities for achieving this goal due to their unique and tunable imaging capabilities. However, most nanoparticles are still in the process of development due to challenges such as retention time and safety issues, and are inaccessible to most researchers. In this article, we investigate the potential application of core-shell fluorescent silica nanoparticles (i.e. C dots), which are commercially available and approved by the FDA for clinical trials. Specifically we demonstrate that 500 nm C dots have prolonged cellular retention (up to one month), minimal contrast agent transfer (at least three weeks) between cells in a co-culture Boyden chamber system, and minimal influence on the hMSC properties including viability, proliferation, differentiation, and tropism to tumor cells.

High fat diet deviates PtC-specific B1 B cell phagocytosis in obese mice.

Phagocytosis had been attributed predominantly to "professional" phagocytes such as macrophages, which play critical roles in adipose tissue inflammation. However, recently, macrophage-like phagocytic activity has been reported in B1 B lymphocytes. Intrigued by the long-established correlation between high fat diet (HFD)-induced obesity and immune dysfunction, we investigated how HFD affects B1 B cell phagocytosis. A significant number of B1 B cells recognize phosphatidylcholine (PtC), a common phospholipid component of cell membrane. We report here that unlike macrophages, B1 B cells have a unique PtC-specific phagocytic function. In the presence of both PtC-coated and non-PtC control fluorescent nano-particles, B1 B cells from healthy lean mice selectively engulfed PtC-coated beads, whereas B1 B cells from HFD-fed obese mice non-discriminately phagocytosed both PtC-coated and control beads. Morphologically, B1 B cells from obese mice resembled macrophages, displaying enlarged cytosol and engulfed more beads. Our study suggests for the first time that HFD can affect B1 B cell phagocytosis, substantiating the link of HFD-induced obesity and immune deviation.

Commercial nanoparticles for stem cell labeling and tracking.

Stem cell therapy provides promising solutions for diseases and injuries that conventional medicines and therapies cannot effectively treat. To achieve its full therapeutic potentials, the homing process, survival, differentiation, and engraftment of stem cells post transplantation must be clearly understood. To address this need, non-invasive imaging technologies based on nanoparticles (NPs) have been developed to track transplanted stem cells. Here we summarize existing commercial NPs which can act as contrast agents of three commonly used imaging modalities, including fluorescence imaging, magnetic resonance imaging and photoacoustic imaging, for stem cell labeling and tracking. Specifically, we go through their technologies, industry distributors, applications and existing concerns in stem cell research. Finally, we provide an industry perspective on the potential challenges and future for the development of new NP products.

Measurement of plasma volume using fluorescent silica-based nanoparticles.

Plasma volume (PV) is an important determinant of cardiovascular function and organ perfusion, and it is the target of infusion and diuretic therapies in daily clinical practice. Despite its fundamental importance PV is not commonly measured because available methods of tracer dilution are reliant on dye substances that suffer from numerous drawbacks including binding plasma proteins, spectral changes, and clearance kinetics that complicate analysis and interpretation. To address these issues, we have tested the utility of fluorescent nanoparticles comprised of a dye-rich silica core and polyethylene glycol-coated shell. Photophysical and visual analysis showed discrete size-gradated nanoparticle populations could be synthesized within a distribution tolerance of ±4 nm, which were optically unaffected in the presence of plasma/albumin. In normal mice, the cutoff for renal filtration of nanoparticles from blood into urine was ≤11 nm. A linear relationship between body weight and PV was readily determined in mice administered far red fluorescent nanoparticles sized either 20 or 30 nm. PV measurements using nanoparticles were correlated to values obtained with Evans blue dye. Induced expansion or contraction of PV was demonstrated with albumin or furosemide administration, respectively, in mice. Longitudinal experiments >30 min required matched untreated control mice to correct for nanoparticle loss (≈30%) putatively to the reticuloendothelial/phagocyte system. Collectively, the findings support a nanotechnology-based solution to methodological problems in measure of PV, notably in clinical settings where information on hemodynamic changes may improve treatment of injury and disease.

Multimodal silica nanoparticles are effective cancer-targeted probes in a model of human melanoma.

Nanoparticle-based materials, such as drug delivery vehicles and diagnostic probes, currently under evaluation in oncology clinical trials are largely not tumor selective. To be clinically successful, the next generation of nanoparticle agents should be tumor selective, nontoxic, and exhibit favorable targeting and clearance profiles. Developing probes meeting these criteria is challenging, requiring comprehensive in vivo evaluations. Here, we describe our full characterization of an approximately 7-nm diameter multimodal silica nanoparticle, exhibiting what we believe to be a unique combination of structural, optical, and biological properties. This ultrasmall cancer-selective silica particle was recently approved for a first-in-human clinical trial. Optimized for efficient renal clearance, it concurrently achieved specific tumor targeting. Dye-encapsulating particles, surface functionalized with cyclic arginine-glycine-aspartic acid peptide ligands and radioiodine, exhibited high-affinity/avidity binding, favorable tumor-to-blood residence time ratios, and enhanced tumor-selective accumulation in αvß3 integrin-expressing melanoma xenografts in mice. Further, the sensitive, real-time detection and imaging of lymphatic drainage patterns, particle clearance rates, nodal metastases, and differential tumor burden in a large-animal model of melanoma highlighted the distinct potential advantage of this multimodal platform for staging metastatic disease in the clinical setting.

Fluorescent silica nanoparticles with efficient urinary excretion for nanomedicine.

The development of molecularly targeted probes that exhibit high biostability, biocompatibility, and efficient clearance profiles is key to optimizing biodistribution and transport across biological barriers. Further, coupling probes designed to meet these criteria with high-sensitivity, quantitative imaging strategies is mandatory for ensuring early in vivo tumor detection and timely treatment response. These challenges have often only been examined individually, impeding the clinical translation of fluorescent probes. By simultaneously optimizing these design criteria, we created a new generation of near-infrared fluorescent core-shell silica-based nanoparticles (C dots) tuned to hydrodynamic diameters of 3.3 and 6.0 nm with improved photophysical characteristics over the parent dye. A neutral organic coating prevented adsorption of serum proteins and facilitated efficient urinary excretion. Detailed particle biodistribution studies were performed using more quantitative ex vivo fluorescence detection protocols and combined optical-PET imaging. The results suggest that this new generation of C dots constitutes a promising clinically translatable materials platform which may be adapted for tumor targeting and treatment.

Fluorescent core-shell silica nanoparticles: towards "Lab on a Particle" architectures for nanobiotechnology.

Novel nanoscale fluorescent materials are integral to the progress of emergent fields such as nanobiotechnology and facilitate new research in a variety of contexts. Sol-gel derived silica is an excellent host material for creating fluorescent nanoparticles by the inclusion of covalently-bound organic dyes. Significant enhancements in the brightness and stability of organic dye emission can be achieved for silica-based core-shell nanoparticle architectures at length scales down to tens of nanometers with narrow size distributions. This tutorial review will highlight these findings and describe the evolution of the fluorescent core-shell silica nanoparticle concept towards integration of multiple functionalities including mesoporosity, metal nanoshells and quantitative chemical sensing. These developments point towards the development of "lab on a particle" architectures with promising prospects for nanobiotechnology, drug development and beyond.

Bright and stable core-shell fluorescent silica nanoparticles.

A class of highly fluorescent and photostable core-shell nanoparticles from a modified Stober synthesis in the size range of 20-30 nm is described. These nanoparticles are monodisperse in solution, 20 times brighter, and more photostable than their constituent fluorophore, and are amenable to specific labeling of biological macromolecules for bioimaging experiments. The photophysical characteristics of the encapsulated fluorophores differ from their solution properties. This raises the possibility of tuning nanoparticle structure toward enhanced radiative properties, making them an attractive material platform for a diverse range of applications.

Ordered mesoporous ceramics stable up to 1500 degrees C from diblock copolymer mesophases.

In the present study, a poly(isoprene-block-dimethylamino ethyl methacrylate) diblock copolymer (PI-b-PDMAEMA) is used to structure-direct a polysilazane pre-ceramic polymer, commercially known as Ceraset. To the polymer was added a 2-fold excess in weight of the silazane oligomer (Ceraset). The resulting composite was cast into films, and after cooperative self-assembly of block copolymer and Ceraset, the structure was permanently set in the hexagonal columnar morphology, as evidenced by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Cross-linking of the silazane oligomer was achieved with a radical initiator at 120 degrees C. Upon heating of the composite to 1500 degrees C under nitrogen, the structure is preserved and a mesoporous ceramic material is obtained, as demonstrated by SAXS and TEM. The pores are open and accessible, as evidenced by nitrogen sorption/desorption measurements indicating a surface area of about 51 m2 g-1 and a pore diameter of 13 nm, consistent with TEM analysis. These results suggest that the use of block copolymer mesophases may provide a simple, easily controlled pathway for the preparation of various high-temperature ceramic mesostructures.

Nanohybrids from liquid crystalline extended amphiphilic dendrimers.

A novel extended amphiphilic dendrimer with linear poly(ethylene oxide) (PEO) attached to a PEO-like dendritic core as hydrophilic fraction and eight docosyl chain branches as hydrophobic fraction has been prepared for the use as structure-directing agent for silica-type materials. The extended dendrimer exhibits a hexagonal columnar liquid crystalline phase in the melt. Organically modified inorganic precursors and the extended dendrimer co-assemble into nanostructured hybrids. Hybrids with 0.44 weight fraction (fw) of aluminosilicate show a lamellar morphology, while hybrids with 0.21 fw exhibit a cylindrical structure. Nanostructures were characterized by a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results suggest that dendrimer-based amphiphiles may provide an exciting platform for the formation of multifunctional organic-inorganic nanostructured hybrid materials with unique structural characteristics.