The impact of zwitterionic surfactants on optode-based nanosensors different fabrication approaches and sensing mechanisms.

In this work, we explored the impact of zwitterionic surfactants, sulfobetaine 16 (SB-16) and a PEG-phospholipid conjugate (DSPE-PEG), on nanosensor performance. We fabricated four sensors (for Na, K, Al, and O) and examined how these surfactants influenced various aspects, including fabrication methods, sensing mechanisms, and the incorporation of nanomaterials. Our results highlighted SB-16's role in enhancing selectivity in ion-exchange sensors (Na and K) while maintaining sensitivity akin to its PEG counterpart.

Increasing aggregate size reduces single-cell organic carbon incorporation by hydrogel-embedded wetland microbes.

Microbial degradation of organic carbon in sediments is impacted by the availability of oxygen and substrates for growth. To better understand how particle size and redox zonation impact microbial organic carbon incorporation, techniques that maintain spatial information are necessary to quantify elemental cycling at the microscale. In this study, we produced hydrogel microspheres of various diameters (100, 250, and 500 μm) and inoculated them with an aerobic heterotrophic bacterium isolated from a freshwater wetland ( sp.

Persistent Luminescence Nanosensors: A Generalized Optode-Based Platform for Autofluorescence-Free Sensing in Biological Systems.

Fluorescent nanosensors have revolutionized diagnostics and our ability to monitor cellular dynamics. Yet, distinguishing sensor signals from autofluorescence remains a challenge. Here, we merged optode-based sensing with near-infrared-emitting ZnGaO:Cr persistent luminescence nanoparticles (PLNPs) to create nanocomposites for autofluorescence-free "glow-in-the-dark" sensing.

Mini Winnies: scaled down and transparent Winogradsky columns for microscopy in microbiology education.

Winogradsky columns were invented by Sergei Winogradsky in the 1880s and have commonly been used as a microbiology classroom learning tool in K-12 and collegiate education. However, they can be challenging to examine with microscopy. We scaled down Winogradsky columns into nuclear magnetic resonance (NMR) tubes and replaced the natural sediment with a transparent soil substitute toward the goal of observing the microbial growth under a bright-field microscope without column disassembly.

Multifunction fluorescence open source in vivo/in vitro imaging system (openIVIS).

The widespread availability and diversity of open-source microcontrollers paired with off-the-shelf electronics and 3D printed technology has led to the creation of a wide range of low-cost scientific instruments, including microscopes, spectrometers, sensors, data loggers, and other tools that can be used for research, education, and experimentation. These devices can be used to explore a wide range of scientific topics, from biology and chemistry to physics and engineering. In this study, we designed and built a multifunction fluorescent open source in vivo/in vitro imaging system (openIVIS) system that integrates a Raspberry Pi with commercial cameras and LEDs with 3D printed structures combined with an acrylic housing.

Triplet-Triplet Annihilation Upconversion-Based Oxygen Sensors to Overcome the Limitation of Autofluorescence.

Autofluorescence is one of the many challenges in bioimaging as it can mask the emission from fluorescent probes or markers, a limitation that can be overcome via upconversion. Herein, we have developed a nanosensor that uses triplet-triplet annihilation upconversion to optically report changes in the dissolved oxygen concentration. Using a sensitizer-annihilator dye pairing of platinum(II) octaethylporphyrin and 9,10-diphenylanthracene, we monitored the oxygen consumption (as a proxy for metabolic activity) over time in a biological system─ (brewing yeast).

Sensors in a Flash! Oxygen Nanosensors for Microbial Metabolic Monitoring Synthesized by Flash Nanoprecipitation.

Flash nanoprecipitation (FNP) is an efficient and scalable nanoparticle synthesis method that has not previously been applied to nanosensor fabrication. Current nanosensor fabrication methods have traditionally exhibited poor replicability and consistency resulting in high batch-to-batch variability, highlighting the need for a more tunable and efficient method such as FNP. We used FNP to fabricate nanosensors to sense oxygen based on an oxygen-sensitive dye and a reference dye, as a tool for measuring microbial metabolism.

A near-infrared optical nanosensor for measuring aerobic respiration in microbial systems.

We developed a ratiometric oxygen-sensitive nanosensor and demonstrated application in monitoring metabolic oxygen consumption in microbial samples over time. Based on a near-infrared (NIR) emitting oxygen-quenched luminophore, platinum(II) octaethylporphine ketone (PtOEPK), along with a stable dioctadecyl dicarbocyanine reference dye (DiD), this nanosensor system provides an advantageous approach for overcoming imaging issues in biological systems, such as autofluorescence and optical scattering in the visible wavelength region. The dyes are encapsulated within a polymer-based nanoparticle matrix to maintain them at a constant ratio in biological samples, precluding the need for complex synthetic approaches.

Nanoparticle-Based Liquid-Liquid Extraction for the Determination of Metal Ions.

Traditional liquid phase extraction techniques that use optically responsive ligands provide benefits that enable cost-efficient and rapid measurements. However, these approaches have limitations in their excessive use of organic solvents and multistep procedures. Here, we developed a simple, nanoscale extraction approach by replacing the macroscopic organic phase with hydrophobic polymeric nanoparticles that are dispersed in an aqueous feed.

Signal transduction with a swing.

The continuous monitoring of proteins is a current challenge in medical diagnostics. A new electrochemical approach aiming to address this has been described. The method uses antibodies as a recognition element to achieve the real-time measurement of proteins in saliva in the mouth.

LipiSensors: Exploiting Lipid Nanoemulsions to Fabricate Ionophore-Based Nanosensors.

Ionophore-based nanosensors (IBNS) are tools that enable quantification of analytes in complex chemical and biological systems. IBNS methodology is adopted from that of bulk optodes where an ion exchange event is converted to a change in optical output. While valuable, an important aspect for application is the ability to intentionally tune their size with simple approaches, and ensure that they contain compounds safe for application.

Nanodiagnostics to monitor biofilm oxygen metabolism for antibiotic susceptibility testing.

In clinical environments, many serious antibiotic-resistant infections are caused by biofilm-forming species. This presents issues when attempting to determine antimicrobial dosing as traditional antibiotic susceptibility tests (ASTs) are typically designed around planktonic bacteria and thus offer information that is not relevant to the biofilm phenotype present in the patient. Even the popular Calgary biofilm device may provide inaccurate minimum biofilm inhibitory concentrations (MBICs) and can be time- and material-intensive.

Triplet-Triplet Annihilation Upconversion Based Nanosensors for Fluorescence Detection of Potassium.

Typical ionophore-based nanosensors use Nile blue derived indicators called chromoionophores, which must contend with strong background absorption, autofluorescence, and scattering in biological samples that limit their usefulness. Here, we demonstrate potassium-selective nanosensors that utilize triplet-triplet annihilation upconversion to minimize potential optical interference in biological media and a pH-sensitive quencher molecule to modulate the upconversion intensity in response to changes in analyte concentration. A triplet-triplet annihilation dye pair (platinum(II) octaethylporphyrin and 9,10-diphenylanthracene) was integrated into nanosensors containing an analyte binding ligand (ionophore), charge-balancing additive, and a pH indicator quencher.

An ionophore-based persistent luminescent 'Glow Sensor' for sodium detection.

Optical sensors have numerous positive attributes such as low invasiveness, miniaturizability, biocompatibility, and ease of signal transduction. Recently, there has been a strong research focus on using phosphorescent readout mechanisms, specifically from long-lifetime phosphorescent or 'persistent luminescence' particles, for and sensors. Persistent luminescence readouts can avoid cellular autofluorescence during biological monitoring, leading to an improved signal-to-noise ratio over a more traditional fluorescence readout.

Luminescent Nanosensors for Ratiometric Monitoring of Three-Dimensional Oxygen Gradients in Laboratory and Clinical Pseudomonas aeruginosa Biofilms.

Bacterial biofilms can form persistent infections on wounds and implanted medical devices and are associated with many chronic diseases, such as cystic fibrosis. These infections are medically difficult to treat, as biofilms are more resistant to antibiotic attack than their planktonic counterparts. An understanding of the spatial and temporal variation in the metabolism of biofilms is a critical component toward improved biofilm treatments.

Optical drug monitoring: photoacoustic imaging of nanosensors to monitor therapeutic lithium in vivo.

Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal, we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo.

Fluorescent sensors for the basic metabolic panel enable measurement with a smart phone device over the physiological range.

The advanced functionality of portable devices such as smart phones provides the necessary hardware to potentially perform complex diagnostic measurements in any setting. Recent research and development have utilized cameras and data acquisition properties of smart phones to create diagnostic approaches for a variety of diseases or pollutants. However, in concentration measurements, such as blood glucose, the performance of handheld diagnostic devices depends largely on the sensing mechanism.

Phosphorescent nanosensors for in vivo tracking of histamine levels.

Continuously tracking bioanalytes in vivo will enable clinicians and researchers to profile normal physiology and monitor diseased states. Current in vivo monitoring system designs are limited by invasive implantation procedures and biofouling, limiting the utility of these tools for obtaining physiologic data. In this work, we demonstrate the first success in optically tracking histamine levels in vivo using a modular, injectable sensing platform based on diamine oxidase and a phosphorescent oxygen nanosensor.

In vivo histamine optical nanosensors.

In this communication we discuss the development of ionophore based nanosensors for the detection and monitoring of histamine levels in vivo. This approach is based on the use of an amine-reactive, broad spectrum ionophore which is capable of recognizing and binding to histamine. We pair this ionophore with our already established nanosensor platform, and demonstrate in vitro and in vivo monitoring of histamine levels.

Wash-free, electrochemical platform for the quantitative, multiplexed detection of specific antibodies.

The diagnosis, prevention, and treatment of many illnesses, including infectious and autoimmune diseases, would benefit from the ability to measure specific antibodies directly at the point of care. Thus motivated, we designed a wash-free, electrochemical method for the rapid, quantitative detection of specific antibodies directly in undiluted, unprocessed blood serum. Our approach employs short, contiguous polypeptide epitopes coupled to the distal end of an electrode-bound nucleic acid "scaffold" modified with a reporting methylene blue.

The design and development of fluorescent nano-optodes for in vivo glucose monitoring.

Background: The advent of fluorescent nanosensors has enabled intracellular monitoring of several physiological analytes, which was previously not possible with molecular dyes or other invasive techniques. We have extended the capability of these sensors to include the detection of small molecules with the development of glucose-sensitive nano-optodes. Herein, we discuss the design and development of glucose-sensitive nano-optodes, which have been proven functional both in vitro and in vivo.

Nanosensors and nanomaterials for monitoring glucose in diabetes.

Worldwide, diabetes is a rapidly growing problem that is managed at the individual level by monitoring and controlling blood glucose levels to minimize the negative effects of the disease. Because of limitations in diagnostic methods, significant research efforts are focused on developing improved methods to measure glucose. Nanotechnology has impacted these efforts by increasing the surface area of sensors, improving the catalytic properties of electrodes and providing nanoscale sensors.

Tracking a molecular motor with a nanoscale optical encoder.

Optical encoders are commonly used in macroscopic machines to make precise measurements of distance and velocity by translating motion into a periodic signal. Here we show how Forster resonance energy transfer can be used to implement this technique at the single-molecule scale. We incorporate a series of acceptor dye molecules into self-assembling DNA, and the periodic signal resulting from unhindered motion of a donor-labeled molecular motor provides nanometer-scale resolution in milliseconds.

A general electrochemical method for label-free screening of protein-small molecule interactions.

Here we report a versatile method by which the interaction between a protein and a small molecule, and the disruption of that interaction by competition with other small molecules, can be monitored electrochemically directly in complex sample matrices.

The length and viscosity dependence of end-to-end collision rates in single-stranded DNA.

Intramolecular dynamics play an essential role in the folding and function of biomolecules and, increasingly, in the operation of many biomimetic technologies. Thus motivated we have employed both experiment and simulation to characterize the end-to-end collision dynamics of unstructured, single-stranded DNAs ranging from 6 to 26 bases. We find that, because of the size and flexibility of the optical reporters employed experimentally, end-to-end collision dynamics exhibit little length dependence at length scales <11 bases.