In article number 1602300, Bruce Dunn, Liqiang Mai, and co-workers present an overview of emerging novel, porous, one-dimensional nanostructures: from methodologies for rational and controllable synthesis to their successful application in different types of energy-storage devices, including lithium-ion batteries, sodium-ion batteries, lithium–sulfur batteries, lithium–oxygen batteries, and supercapacitors.
Research in recent years has demonstrated that biological molecules such as enzymes, immunoglobulins, and other proteins can be immobilized in sol-gel derived matrices and retain their biological function. Development of glasses with encapsulated biomolecules has opened the possibility of solid-state optical biosensors for the detection and measurement of desired analytes. In this work, we report the successful use of sol-gel silica glasses with encapsulated antibodies for the detection of trinitrotoluene (TNT). Results show that both competitive immunoassay and displacement immunoassay are feasible using antibody-doped glasses, and these materials can detect TNT at < 1 ppm. Moreover, the sol-gel immobilized antibodies retained the ability to discriminate between TNT and an analog, trinitrobenzene. Finally, enhanced stability was observed in the sol-gel immobilized as compared to surface immobilized antibodies.
An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more rugged sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection
Antibodies to trinitrotoluene (TNT) were encapsulated in optically transparent sol−gel derived silica glasses and retained their ability to bind TNT. Both competitive and displacement immunoassays were successfully performed using sol−gel immobilized antibodies. TNT concentrations on the order of ppm were detected. In competitive immunoassays using the sol−gel immobilized antibodies, a logarithmic decrease in fluorescence signal as a function of TNT concentration was observed, similar to competitive immunoassays performed in solution. When encapsulated in the sol−gel silica matrix, the antibodies retained their ability to differentiate between TNT and trinitrobenzene (TNB), an analogue. In displacement immunoassays, the rate of displacement was dependent upon pore morphology, with aged gels exhibiting faster rates than that of xerogels. The relative stability of antibodies was better for sol−gel encapsulated antibodies than for antibodies immobilized using surface attachment. After exposure to HCl, methanol, or 60 °C, the sol−gel immobilized antibodies experienced essentially no loss in ability to bind TNT whereas the surface immobilized antibodies showed as much as 30% loss in ability to bind TNT.
The effects of atomic oxygen on boron nitride (BN) and silicon nitride (Si3N4) have been studied in low Earth orbit (LEO) flight experiments and in a ground-based simulation facility at Los Alamos National Laboratory. Both the in-flight and ground-based experiments employed the materials coated over thin (approx 250 Angstrom) silver films whose electrical resistance was measured in situ to detect penetration of atomic oxygen through the BN and Si3N4 materials. In the presence of atomic oxygen, silver oxidizes to form silver oxide, which has a much higher electrical resistance than pure silver. Permeation of atomic oxygen through BN, as indicated by an increase in the electrical resistance of the silver underneath, was observed in both the in-flight and ground-based experiments. In contrast, no permeation of atomic oxygen through Si3N4 was observed in either the in-flight or ground-based experiments. The ground-based results show good qualitative correlation with the LEO flight results, thus validating the simulation fidelity of the ground-based facility in terms of reproducing LEO flight results.
Abstract Objectives To evaluate the impact of a dietary supplement within an elderly population who reside in a Community Living Center (CLC; VA Nursing Home), on the number of respiratory tract infections (RTIs) during a 90-day study period. Methods This is a randomized, double-blind, placebo-controlled study to evaluate the impact of bovine Lactoferrin (bLf) on RTIs in an elderly nursing home population in the US. Subjects will be residents of the CLC and screened within 21 days prior to starting study supplementation. Eligible participants were at least 55 years of age, able to eat and drink and expected to reside at the CLC for the duration of the study. Consent was obtained from the study participant or their legally recognized representative decision maker. Participants will be excluded if: receiving tube feeds or specialized diets for eating disorders; immunocompromised; have a life expectancy of less than six months; or allergic to study products. Results Subjects will be randomized in a ratio of 1:1 to either investigational (600 mg of bLf) or (placebo arms. All participants will take study supplement by mouth daily for 90 days. Subjects will be assessed daily for RTI symptoms. Blood and saliva will be collected at 45 and 90 days. Ad hoc assessments and a nasal sample will take place if a subject develops a protocol-defined RTI. Conclusions The primary outcome will be number of RTIs over the 90-day study period. Secondary outcomes include severity and duration of RTI symptoms, symptoms associated with RTIs, number of RTI complications, and nasopharyngeal swab at onset of RTI, Other secondary outcomes include the following, all measured at baseline, day 45 and day 90: quality of life by questionnaire, weight, saliva markers, laboratory testing and immunological markers. An exploratory endpoint is vaccine specific inflammatory panel (influenza and Sars-Cov2) measured upon vaccination during supplement period. RTI number, severity, duration and complications and medically confirmed adverse events will be compared between the placebo and investigational groups. Funding Sources RB/Mead Johnson & Company.
SummaryThe sol-gel process is a chemical technique for immobilizing biomolecules in an inorganic, transparent matrix. The dopant biomolecules reside in an interconnected mesoporous network and become part of the nanostructured architecture of the entire material. In this chapter, we review the sol-gel immobilization approach and discuss how it leads to the stabilization of a number of proteins against aggressive chemical and thermal environments. We also review the sensor applications of this material that result from having analyte molecules diffuse through the matrix and reach the immobilized biomolecule.
This chapter contains sections titled: Introduction and Background Method/Technique/Approach Applications General Discussion Concluding Remarks and Future Directions Acknowledgments References
