Corona Phase Research Articles

High-Throughput Approaches to Engineer Fluorescent Nanosensors.

Optical sensors are powerful tools to identify and image (biological) molecules. Because of their optoelectronic properties, nanomaterials are often used as building blocks. To transduce the chemical interaction with the analyte into an optical signal, the interplay between surface chemistry and nanomaterial photophysics has to be optimized. Understanding these aspects promises major opportunities for tailored sensors with optimal performance. However, this requires methods to create and explore the many chemical permutations. Indeed, many current approaches are limited in throughput. This affects the chemical design space that can be studied, the application of machine learning approaches as well as fundamental mechanistic understanding. Here, an overview of selection-limited and synthesis-limited approaches is provided to create and identify molecular nanosensors. Bottlenecks are discussed and opportunities of non-classical recognition strategies are highlighted such as corona phase molecular recognition as well as the requirements for high throughput and scalability. Fluorescent carbon nanotubes are powerful building blocks for sensors and their huge chemical design space makes them an ideal platform for high throughput approaches. Therefore, they are the focus of this article, but the insights are transferable to any nanosensor system. Overall, this perspective aims to provide a fresh perspective to overcome current challenges in the nanosensor field.

Graben systems and geological history of Mbokomu Mons region, Parga Chasmata, Venus

The relationship between chasmata (rift zones) and spatially associated volcanism (mons and coronae) on Venus has been extensively discussed but remains enigmatic. One region where these features are prominently displayed is along the 10,000 km long, WNW trending, Parga Chasmata, which connects Atla Regio with Themis Regio. The Mbokomu Mons area (located about 2200 km SE of Atla Regio) was selected for detailed study to provide insight into these relationships. More than 39,000 extensional lineaments (grabens, fissures and fractures) were mapped at 1:500,000 scale using full resolution Magellan Synthetic Aperture Radar (SAR) images and grouped into radiating, circumferential and linear systems. They are (except where noted) interpreted to represent the surface expression of underlying mafic dyke swarms, on the basis of associated volcanic features and terrestrial analogues. Radiating and/or circumferential swarms are associated with Mbokomu Mons and the four coronae in the surrounding area, Among Corona (AC), Repa Corona (RC) and two unnamed coronae (UC1 and UC2). Mbokomu Mons is unique among the tectono-magmatic features in this region of Parga Chasmata, in having both corona and mons characteristics. The initial Corona Phase consists of radiating and circumferential systems mainly preserved in an unflooded annular uplift, while the Mons Phase includes a second radiating swarm associated with a central edifice, and smaller circumferential fracture pattern near the summit that could overlie a magma reservoir. The plume or diapir that is interpreted to have been responsible for the initial Corona Phase is estimated to have had a radius of ∼150 km. Cross-cutting relationships indicate that Mbokomu Mons is younger than nearby Among, Oduduwa and Onenhtse coronae. All four centres are aligned along a WNW-trend parallel to the Parga Chasmata (rift system). Mbokomu Mons is located at, and its emplacement may be linked to, the intersection of this WNW-trending zone of weakness and the orthogonal Jokwa Linea rift system. Mbokumo Mons is also younger than the nearby parallel Penthesilia Fossa (PF) (part of the Great Dyke of Atla Regio).

Rationally Designed Functionalization of Single-Walled Carbon Nanotubes for Real-Time Monitoring of Cholinesterase Activity and Inhibition in Plasma.

Enzymes play a pivotal role in regulating numerous bodily functions. Thus, there is a growing need for developing sensors enabling real-time monitoring of enzymatic activity and inhibition. The activity and inhibition of cholinesterase (CHE) enzymes in blood plasma are fluorometrically monitored using near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) as probes, strategically functionalized with myristoylcholine (MC)- the substrate of CHE. A significant decrease in the fluorescence intensity of MC-suspended SWCNTs upon interaction with CHE is observed, attributed to the hydrolysis of the MC corona phase of the SWCNTs by CHE. Complementary measurements for quantifying choline, the product of MC hydrolysis, reveal a correlation between the fluorescence intensity decrease and the amount of released choline, rendering the SWCNTs optical sensors with real-time feedback in the NIR biologically transparent spectral range. Moreover, when synthetic and naturally abundant inhibitors inhibit the CHE enzymes present in blood plasma, no significant modulations of the MC-SWCNT fluorescence are observed, allowing effective detection of CHE inhibition. The rationally designed SWCNT sensors platform for monitoring of enzymatic activity and inhibition in clinically relevant samples is envisioned to not only advance the field of clinical diagnostics but also deepen further understanding of enzyme-related processes in complex biological fluids.

Ionic Strength-Mediated "DNA Corona Defects" for Efficient Arrangement of Single-Walled Carbon Nanotubes.

Single-stranded DNA oligonucleotides wrapping on the surface of single-walled carbon nanotubes (SWCNTs), described as DNA corona, are often used as a dispersing agent for SWCNTs. The uneven distribution of DNA corona along SWCNTs is related to the photoelectric properties and the surface activity of SWCNTs. An ionic strength-mediated "DNA corona defects" (DCDs) strategy is proposed to acquire an exposed surface of SWCNTs (accessible surface) as large as possible while maintaining good dispersibility via modulating the conformation of DNA corona. By adjusting the solution ionic strength, the DNA corona phase transitioned from an even-distributed and loose conformation to a locally compact conformation. The resulting enlarged exposed surface of SWCNTs is called DCDs, which provide active sites for molecular adsorption. This strategy is applied for the arrangement of SWCNTs on DNA origami. SWCNTs with ≈11nm DCD, providing enough space for the adsorption of "capture ssDNA" (≈7nm width required for 24-nt) extended from DNA origami structures are fabricated. The DCD strategy has potential applications in SWCNT-based optoelectronic devices.

Nitric Oxide Detection Using a Corona Phase Molecular Recognition Site on Chiral Single-Walled Carbon Nanotubes.

Semiconducting single-walled carbon nanotubes (s-SWCNT) are structures that fluoresce in the near-infrared region. By coating SWCNT surfaces with polymeric materials such as single-chain DNA, changes in fluorescence emission occur in the presence of reagents. In this way, polymer-coated SWCNT structures allow them to be used as optical sensors for single molecule detection. Especially today, the inadequacy of the methods used in the detection of cellular molecules makes the early diagnosis of diseases such as cancer difficult at the single-molecule level. In this study, the detection of nitric oxide (NO) signals, which are a marker of cancer, was carried out at the single-molecule level. In this context, a sensor structure was formed by coating the 7,6-chiral s-SWCNT surface with ssDNA with different oligonucleotide lengths (AT). The sensor structure was characterized by using UV-vis spectroscopy and Raman spectroscopy microscopy. After formation of the sensor structure, a selectivity library was created using various molecules. As a result of the coating of the SWCNT (7,6) surface with DNA corona phase formation, Raman peaks at 195 and 276 cm-1 were observed to shift to the right. Additionally, the selectivity library results showed that the (AT)30 sequence can be used in NO detection. As a result of the studies using SWCNT (7.6)- (AT)30, the limit of detection (LOD) and limit of determination (LOQ) values of the sensor against NO were found to be 1.24 and 4.13 μM, respectively.

Laser Fluence Dependent Modulation of Single Walled Carbon Nanotube Photoluminescence

Single-walled carbon nanotubes (SWCNT) have a unique, non-photobleaching, bandgap photoluminescence (PL) that has been of interest for sensor development. Take advantage of these properties, colloidal dispersions of single SWCNTs in aqueous solvents are often formed by creating a surface corona phase (CP) using amphiphilic materials. As SWCNT PL emission following photoexcitation can be significantly dependent on its local environment, the CP can be used to tune its photophysical properties, often as a design parameter for sensor development. Recent sensor experiments have shown that reporting and controlling laser excitation can be a method to significantly reduce measurement variability. In this work, we study this phenomenon of excitation fluence (EF) (mW/area) dependent PL modulation for aqueous dispersed SWCNTs. By using a continuously stirred chamber excited at a single location, the stirring rate can be a means of controlling SWCNT excitation exposure. SWCNT wrapped in both DNA and SDS SWCNT CPs showed a decreased quantum yield of nearly 40% with increasing EF while those with sodium cholate and phospholipid-PEG CPs remain invariant. Through spectroscopy and heat transfer modeling, we determined that the observed effect is unlikely to have a significant direct local solution heating contribution from SWNCT photoabsorption. Finally, we used previously studied SWCNT sensor constructs, for ascorbic acid and dopamine, to show how EF can affect calibration and eventual sensor applications. This work highlights the importance of measuring, testing, reporting and controlling for EF while developing SWCNT based photophysical sensors. This newly characterized property can also serve as a unique parameter to tune optical responsivity.

Corona Phase Molecular Recognition of Interleukin-6 Family Cytokines Using Nir Single Walled Carbon Nanotube

The Interleukin-6 (IL-6) family of cytokines regulate inflammation and play important roles in numerous biochemical pathways. Understanding the fundamental molecular recognition of these molecules with synthetic substrates is key to new biomedical technologies, including assays and sensors, therapeutics and purification methods. In this work, we use Corona Phase Molecular Recognition (CoPhMoRe) to engineer new carbon nanotubes corona phases and study nanotube binding to IL6. Library screening identifies two CoPhMoRe constructs based on carbon nanotube complexation with a p(AA68-rand-BA 16 -rand-CD 16 ) polymer (MK2) and a p(SS80-rand-BS 20 ) polymer (P14) corona phases respectively. Both exhibit KD of binding of 8.38 ng/mL and 16.7 μg/mL respectively, with MK2 construct having a response function consistent with two stage binding for IL-6. Comparative binding experiments show that both constructs appear to recognize the axially aligned alpha-helical structures present in the IL-6 and other IL-6 family cytokines. The findings from this study elucidate how nanoparticle interfaces can be designed to lock onto specific protein features, particularly alpha-helical structures, to enable molecular recognition and new types of sensing technologies.

Understanding Oligonucleotide Hybridization and the Role of Anchoring on the Single-Walled Carbon Nanotube Corona Phase for Viral Sensing Applications

Semiconducting single-walled carbon nanotubes (SWCNTs) with tailored corona phases (CPs), or surface adsorbed molecules, have emerged as a promising interface for sensing applications. The adsorption of an analyte can be specifically transduced as a modulation of their band gap near-infrared (nIR) photoluminescence (PL). One such CP ideal for this purpose is single-stranded DNA (ssDNA), where subsequent sequence dependent hybridization can result in PL emission wavelength shifts. Due to ssDNA adsorption to the SWCNT surface, the resultant non-canonical hybridization and its effect on SWCNT photophysical properties are not well understood. In this work, we study 20- and 21-mer DNA and RNA hybridization on the complementary ssDNA-SWCNT CP in the context of nucleic acid sensing for SARS-CoV-2 sequences as model analytes. We found that the van’t Hoff transition enthalpy of hybridization on SWCNT CP was -11.9 kJ mol-1, much lower than that of hybridization in solution (-707 kJ mol-1). We used SWCNT solvatochromism to calculate the solvent exposed surface area to indicate successful hybridization. We found that having a 30-mer anchor region in addition to the complementary region significantly improved PL response sensitivity and selectivity, with (GT)15 anchor preferred for RNA targets. Coincubation of ssDNA-SWCNT with analyte at 37°C resulted in faster hybridization kinetics without sacrificing specificity. Other methods aimed to improve CP rearrangement kinetics such as bath sonication and surfactant additions were ineffective. We also determined that target sequence choice is important as secondary structure formation in target is negatively correlated with hybridization. Best performing CPs showed detection limits of 11 nM and 13 nM for DNA and RNA targets respectively. Finally, we simulated sensing conditions using saliva environment, showing sensor compatibility in biofluids. In total, this work elucidates key design features and processing to enable sequence specific hybridization on ssDNA-SWCNT CP.

Detection of the Inflammatory Cytokine IL-6 in Complex Human Serum Samples Via Rational Nanotube Surface Passivation Screening

In recent years, biosensors have emerged as a tool with strong potential in medical diagnostics. Single-walled carbon nanotube (SWCNT) based optical nanosensors have notably garnered interest due to the unique characteristics of their near-infrared fluorescence emission, including tissue transparency, photostability, and various chiralities with discrete absorption and fluorescence emission bands.The optoelectronic properties of SWCNT are sensitive to the surrounding environment, which makes them suitable for highly selective biosensing. Single-stranded (ss) DNA-wrapped SWCNTs have been reported as optical nanosensors for cancers and metabolic diseases. However, given the complexity of the human protein environment, non-specific interactions occur between SWCNT-based nanosensors and proteins. This inevitably leads to compromised selectivity of SWCNT-based nanosensors unless strategies for prevention are developed and employed.Non-covalent passivation of the ssDNA-SWCNT surface is reported as an excellent strategy to improve nanosensor selectivity in complex biological settings without causing irreversible changes to the optical properties of SWCNTs. Emerging studies have explored and successfully shown passivation using proteins and phospholipids. However, a systematic comparative study of passivating agents has not been done. In this work, we explore and compare the efficacy of select proteins, polymers, and surfactants as passivating agents.We, therefore, sought to evaluate various potential SWCNT surface passivation agents among broad classes of biomolecules and biomaterials. In the category of protein, Bovine serum albumin, dry-fat milk powder, and casein were selected due to their wide application to improve immunoassay selectivity. In the class of polymers, we selected 1 anionic and 2 cationic polymers, namely, polyethylene glycol, poly-ethylene imine, and poly-l-lysine. From surfactants, 2 phospholipids and 1 anionic surfactant: ammonium salt of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (16:0 PE2000PEG); 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE PEG phospholipids), and sodium dodecylbenzene sulfonate (SDBS) were selected.We analyzed the ability of all passivation agents to screen the non-specific interactions of ssDNA- SWCNTs in the presence of fetal bovine serum using fluorescence spectroscopy. The non-specific interactions between ssDNA-SWCNTs and proteins lead to a reorientation of the dipole moments and charge transfer in the corona phase around ssDNA-SWCNTs, leading to modulation in the center wavelength of the fluorescence as well as absorption peaks. We hence hypothesized that smaller changes in the center wavelength of the fluorescence peaks of passivated ssDNA-SWCNTs in presence of serum, lead to higher screening effect of the passivation agent towards non-specific interactions. We found that the most successful candidates were poly-L-lysine, polyethylene imine, dry-fat milk powder, and casein, in that order. Moreover, the ability to screen the interference was retained over a period of at least 3 hours. We further experimented with the four different mass ratios of passivating agents to ssDNA-SWCNTs and found that the mass ratio 50:1 for passivating agents: ss-DNA SWCNTs was most optimal.We confirmed the strength of passivation using absorption spectroscopy. We hypothesized that stronger surface saturation of the SWCNT-TAT6 is by a passivating agent in buffer conditions leads to a larger shift in the absorption peaks. We found that for the above successful passivation agents, the order of passivation strength followed the same trend as the screening abilities of the successful passivating agents, supporting this mechanistic hypothesis.Then, we evaluated an antibody-conjugated ssDNA-SWCNT nanosensor for the pro-inflammatory cytokine IL-6 with our successful passivation agents. We assessed the ability of the passivation agents to confer selective detection of IL-6 detection in clinical serum samples from patients with atherosclerosis and rheumatoid arthritis, both anticipated to have high IL-6 levels. Samples were compared to healthy human serum sample controls. We validated SWCNT fluorescence response with traditional immunoassays (ELISA).We expect this study to provide rational strategies to screen interferences from non-specific interactions and improve the selectivity of the SWCNT-based optical nanosensors for in vivo applications.

Corona Phase Molecular Recognition of the Interleukin-6 (IL-6) Family of Cytokines Using nIR Fluorescent Single-Walled Carbon Nanotubes

The Interleukin-6 (IL-6) family of cytokines regulates inflammation and plays important roles in numerous biochemical pathways. Typically, cytokine levels are measured using enzyme-linked immunosorbent assay (ELISA) or western blot. However, these techniques usually require substantial processing time, cost, machinery, and specialist training. Understanding the fundamental molecular recognition mechanism of cytokines with synthetic substrates is key to developing new biomedical technologies such as assays, sensors, and therapeutics that overcome the above limitations. Herein, we use the corona phase molecular recognition (CoPhMoRe) approach to engineer new carbon nanotube constructs and study their binding to the inflammatory cytokines: IL-6, interleukin-11 (IL-11), ciliary neurotrophic factor (CNTF), and leukemia inhibitory factor (LIF). Library screening identified two polymer-based CoPhMoRe constructs consisting of single-walled carbon nanotubes complexed with p(AA68-rand-BA16-rand-CD16) polymer (MK2) or p(SS80-rand-BS20) polymer (P14) corona phases. The resulting dissociation constants (KD) were 8.38 ng/mL and 16.7 μg/mL, respectively, compared to that of the natural IL-6 receptor at ∼0.32 ng/mL. In addition, the MK2 constructs showed a nonmonotonic response function upon binding with IL-6. Comparative binding experiments suggest that both constructs appear to recognize the axially aligned α-helical structures present in the Interleukin-6 family. The findings from this study elucidate how nanoparticle interfaces, such as those produced by CoPhMoRe, can be designed to lock onto specific protein features. We find that the α-helical structure of the IL-6 family of cytokines can enable facile molecular recognition, opening the door to new types of label-free, low-cost sensing technologies.

Characterizing the Interactions of Cell-Membrane-Disrupting Peptides with Lipid-Functionalized Single-Walled Carbon Nanotubes.

Lipid-functionalized single-walled carbon nanotubes (SWNTs) have garnered significant interest for their potential use in a wide range of biomedical applications. In this work, we used molecular dynamics simulations to study the equilibrium properties of SWNTs surrounded by the phosphatidylcholine (POPC) corona phase and their interactions with three cell membrane disruptor peptides: colistin, TAT peptide, and crotamine-derived peptide. Our results show that SWNTs favor asymmetrical positioning within the POPC corona, so that one side of the SWNT, covered by the thinnest part of the corona, comes in contact with charged and polar functional groups of POPC and water. We also observed that colistin and TAT insert deeply into the POPC corona, while crotamine-derived peptide only adsorbs to the corona surface. In separate simulations, we show that three examined peptides exhibit similar insertion and adsorption behaviors when interacting with POPC bilayers, confirming that peptide-induced perturbations to POPC in conjugates and bilayers are similar in nature and magnitude. Furthermore, we observed correlations between the peptide-induced structural perturbations and the near-infrared emission of the lipid-functionalized SWNTs, which suggest that the optical signal of the conjugates transduces the morphological changes in the lipid corona. Overall, our findings indicate that lipid-functionalized SWNTs could serve as simplified cell membrane model systems for prescreening of new antimicrobial compounds that disrupt cell membranes.

Review Paper on Characteristic Study of Water Sample for Public Schools and Colleges in Yavatmal

Abstract: This is a project of public interest and the child's immune system is particularly fragile following the corona phase. Water testing is so crucial, and this is the most crucial truth. why did we select this topic? We believe that the majority of the disease-causing bacteria are present in the water, which is the only reason we are testing the water sample. It is an environmentally friendly and crucial project for Yavatmal City because it is located in a hilly area and that most schoolchildren are no longer attending because of health concerns. Water is a valuable resource, and life on earth is impossible without it. Due to excessive and negligent use, water is becoming more and more polluted, and as a result, less and less of it is available for human use. Water pollution can be caused in a variety of ways, and both living things and non-living things are negatively impacted. In current situation water is a more contaminated that’s why it is verry essential to check the quality of water. The causes of water pollution include sewage systems, industrial waste, acid rain, the oil industry, aquatic plants, and household garbage. We studied environmental engineering in the previous section, when we looked at the water quality found in nature. It is well known; the quality of the water is not verified after a corona. As a result, we are undertaking this endeavour for public benefit.

Understanding Oligonucleotide Hybridization and the Role of Anchoring on the Single-Walled Carbon Nanotube Corona Phase for Viral Sensing Applications

Semiconducting single-walled carbon nanotubes (SWCNTs) with tailored corona phases (CPs), or surface-adsorbed molecules, have emerged as a promising interface for sensing applications. The adsorption of an analyte can be specifically transduced as a modulation of their band-gap near-infrared (nIR) photoluminescence (PL). One such CP ideal for this purpose is single-stranded DNA (ssDNA), where subsequent sequence-dependent hybridization can result in PL emission wavelength shifts. Due to ssDNA adsorption to the SWCNT surface, the resultant noncanonical hybridization and its effect on SWCNT photophysical properties are not well understood. In this work, we study 20- and 21-mer DNA and RNA hybridization on the complementary ssDNA-SWCNT CP in the context of nucleic acid sensing for SARS-CoV-2 sequences as model analytes. We found that the van’t Hoff transition enthalpy of hybridization on SWCNT CP was −11.9 kJ mol–1, much lower than that of hybridization in solution (−707 kJ mol–1). We used SWCNT solvatochromism to calculate the solvent-exposed surface area to indicate successful hybridization. We found that having a 30-mer anchor region in addition to the complementary region significantly improved PL response sensitivity and selectivity, with a (GT)15 anchor preferred for RNA targets. Coincubation of ssDNA-SWCNTs with an analyte at 37 °C resulted in faster hybridization kinetics without sacrificing specificity. Other methods aimed to improve CP rearrangement kinetics such as bath sonication and surfactant additions were ineffective. We also determined that the target sequence choice is important as secondary structure formation in the target is negatively correlated with hybridization. Best-performing CPs showed detection limits of 11 and 13 nM for DNA and RNA targets, respectively. Finally, we simulated sensing conditions using the saliva environment, showing sensor compatibility in biofluids. In total, this work elucidates key design features and processing to enable sequence-specific hybridization on ssDNA-SWCNT CPs.

Molecular Recognition and In Vivo Detection of Temozolomide and 5-Aminoimidazole-4-carboxamide for Glioblastoma Using Near-Infrared Fluorescent Carbon Nanotube Sensors

There is a pressing need for sensors and assays to monitor chemotherapeutic activity within the human body in real time to optimize drug dosimetry parameters such as timing, quantity, and frequency in an effort to maximize efficacy while minimizing deleterious cytotoxicity. Herein, we develop near-infrared fluorescent nanosensors based on single walled carbon nanotubes for the chemotherapeutic Temozolomide (TMZ) and its metabolite 5-aminoimidazole-4-carboxamide using Corona Phase Molecular Recognition as a synthetic molecular recognition technique. The resulting nanoparticle sensors are able to monitor drug activity in real-time even under in vivo conditions. Sensors can be engineered to be biocompatible by encapsulation in poly(ethylene glycol) diacrylate hydrogels. Selective detection of TMZ was demonstrated using U-87 MG human glioblastoma cells and SKH-1E mice with detection limits below 30 μM. As sensor implants, we show that such systems can provide spatiotemporal therapeutic information in vivo, as a valuable tool for pharmacokinetic evaluation. Sensor implants are also evaluated using intact porcine brain tissue implanted 2.1 cm below the cranium and monitored using a recently developed Wavelength-Induced Frequency Filtering technique. Additionally, we show that by taking the measurement of spatial and temporal analyte concentrations within each hydrogel implant, the direction of therapeutic flux can be resolved. In all, these types of sensors enable the real time detection of chemotherapeutic concentration, flux, directional transport, and metabolic activity, providing crucial information regarding therapeutic effectiveness.

Divalent Metal Cation Optical Sensing Using Single-Walled Carbon Nanotube Corona Phase Molecular Recognition.

Colloidal single-walled carbon nanotubes (SWCNTs) offer a promising platform for the nanoscale engineering of molecular recognition. Optical sensors have been recently designed through the modification of noncovalent corona phases (CPs) of SWCNTs through a phenomenon known as corona phase molecular recognition (CoPhMoRe). In CoPhMoRe constructs, DNA CPs are of great interest due to the breadth of the design space and our ability to control these molecules with sequence specificity at scale. Utilizing these constructs for metal ion sensing is a natural extension of this technology due to DNA's well-known coordination chemistry. Additionally, understanding metal ion interactions of these constructs allows for improved sensor design for use in complex aqueous environments. In this work, we study the interactions between a panel of 9 dilute divalent metal cations and 35 DNA CPs under the most controlled experimental conditions for SWCNT optical sensing to date. We found that best practices for the study of colloidal SWCNT analyte responses involve mitigating the effects of ionic strength, dilution kinetics, laser power, and analyte response kinetics. We also discover that SWCNT with DNA CPs generally offers two unique sensing states at pH 6 and 8. The combined set of sensors in this work allowed for the differentiation of Hg2+, Pb2+, Cr2+, and Mn2+. Finally, we implemented Hg2+ sensing in the context of portable detection within fish tissue extract, demonstrating nanomolar level detection.

Mechanical Stability of DNA Corona Phase on Gold Nanospheres.

Noncovalent adsorption of biopolymers on the surface of gold nanoparticles (AuNPs) forms a corona phase that drastically diversify AuNP functions. However, mechanical stabilities of such corona phase are still obscure, hindering the application of biopolymer-coated AuNPs. Here, using optical tweezers, we have observed, for the first time, that DNA corona phase adsorbed on a 5 nm AuNP via two (dA)21 strands in proximity can withstand an average desorption force of 40 pN, which is higher than the stall force of DNA/RNA polymerases. This suggests a new role for AuNPs to modulate replications or transcriptions after binding to prevalent poly(dA) segments in eukaryotic genomes. We have also revealed that with increasing AuNP size (1.8-10 nm), DNA corona becomes harder to remove, likely due to the larger surfaces and flatter facets on bigger AuNPs. These findings provide guidance to design AuNP corona that can withstand harsh environments for biological and materials applications.

An Algorithmic Approach for Developing Single-Walled Carbon Nanotube Optical Sensors Against Adulterants in Aquaculture

The nanoparticle corona phase (CP) offers a unique materials design space for constructs capable of molecular recognition (MR) for sensing applications. Single-walled carbon nanotube (SWCNT) CPs have the additional ability to transduce MR through its band gap photoluminescence (PL). DNA oligonucleotides are well-known to disperse SWCNTs through forming CPs and can be manufactured with molecular precision. Nevertheless, no generalized scheme exists for the de novo prediction of SWCNT MR based on these CPs due to their sequence-dependent three-dimensional complexity.In aquaculture, there exist a pressing need for rapid tests for the detection of commonly harmful adulterants such as metal ions and small molecule antibiotics. Through a screening process, we found that DNA-SWCNTs offer a rich design space for MR capable of differentiating divalent metal ions. We also created best practices for the study of colloidal SWCNT analyte responses involve mitigating the effects of ionic strength, dilution kinetics, laser power and analyte response kinetics.Next, we generated the largest DNA-SWCNT PL response library of 1408 elements against 4 adulterant targets. We leveraged machine learning (ML) techniques and used both local features (LFs) and high-level features (HLFs) of the DNA sequences were utilized as model inputs. Out-of-sample analysis of our ML model showed significant correlations between model predictions and actual sensor responses for 6 out of the 8 tested experimental conditions. Furthermore, models utilizing both LFs and HLFs show improvement over that with HLFs alone, demonstrating that DNA-SWCNT CP engineering is more complex than simply specifying general DNA molecular properties. Taken as a whole, we detail the feasibility and utility of a ML-guided approach for nanoparticle CP engineering with relatively few experiments within a high-dimensional design space.

(Invited) Real-Time Detection of Insulin Secreted By Pancreatic β-Cells Using Single-Walled Carbon Nanotube Sensors

Quantification of insulin is essential for diabetes research in general, and for the study of pancreatic β-cell function in particular. Fluorescent single-walled carbon nanotubes (SWCNTs) find many applications as optical nanosensors for biomolecules, proteins, and enzyme, with real-time feedback on target analyte binding1–4. Herein, fluorescent SWCNT are used for the recognition and real-time quantification of insulin5. Two approaches for rendering the SWCNT sensors for insulin are compared, using surface functionalization with either a natural insulin aptamer with known affinity to insulin, or a synthetic lipid-PEG, both of which show a modulation of the emitted fluorescence in response to insulin. Although the PEGylated-lipid has no prior affinity to insulin, its response to insulin is more stable and reproducible compared to the insulin aptamer-SWCNTs. The SWCNT sensors successfully detect and quantify insulin secreted by β-cells within the complex environment of the conditioned media, and the results are found to be in agreement with an enzyme-linked immunosorbent assay5. This novel analytical tool for real time quantification of insulin secreted by β-cells provides new opportunities for rapid assessment of β-cell function.(1) Bisker, G.; Dong, J.; Park, H. D.; Iverson, N. M.; Ahn, J.; Nelson, J. T.; Landry, M. P.; Kruss, S.; Strano, M. S. Protein-Targeted Corona Phase Molecular Recognition. Nat. Commun. 2016, 7, 1–14.(2) Bisker, G.; Bakh, N. A.; Lee, M. A.; Ahn, J.; Park, M.; O’Connell, E. B.; Iverson, N. M.; Strano, M. S. Insulin Detection Using a Corona Phase Molecular Recognition Site on Single-Walled Carbon Nanotubes. ACS Sensors 2018, 8 (2), 367–377.(3) Amir, D.; Hendler-Neumark, A.; Wulf, V.; Ehrlich, R.; Bisker, G. Oncometabolite Fingerprinting Using Fluorescent Single-Walled Carbon Nanotubes. Adv. Mater. Interfaces 2021.(4) Wulf, V.; Slor, G.; Rathee, P.; Amir, R. J.; Bisker, G. Dendron-Polymer Hybrids as Tailorable Coronae of Single-Walled Carbon Nanotube. ChemRxiv 2021. https://doi.org/10.26434/ChemRxiv.14452785.V1.(5) Ehrlich, R.; Hendler‐Neumark, A.; Wulf, V.; Amir, D.; Bisker, G. Optical Nanosensors for Real‐Time Feedback on Insulin Secretion by Β‐Cells. Small 2021, 17 (30), 2101660.

Machine learning for the discovery of molecular recognition based on single-walled carbon nanotube corona-phases

Nanoparticle corona phase (CP) design offers a unique approach toward molecular recognition (MR) for sensing applications. Single-walled carbon nanotube (SWCNT) CPs can additionally transduce MR through its band-gap photoluminescence (PL). While DNA oligonucleotides have been used as SWCNT CPs, no generalized scheme exists for MR prediction de novo due to their sequence-dependent three-dimensional complexity. This work generated the largest DNA-SWCNT PL response library of 1408 elements and leveraged machine learning (ML) techniques to understand MR and DNA sequence dependence through local (LFs) and high-level features (HLFs). Out-of-sample analysis of our ML model showed significant correlations between model predictions and actual sensor responses for 6 out of 8 experimental conditions. Different HLF combinations were found to be uniquely correlated with different analytes. Furthermore, models utilizing both LFs and HLFs show improvement over that with HLFs alone, demonstrating that DNA-SWCNT CP engineering is more complex than simply specifying molecular properties.

Experiences with Regional Medical Coordinators in Ambulatory Care in the Early COVID-19 Phase 2020 in Bavaria: Survey of Regional Ambulatory Coordinators and General Practitioners

During the state of emergency in Bavaria in the early Corona phase 2020, some physicians in ambulatory care were appointed as regional medical coordinators (RMCs). The aim of the present study was to evaluate this newly introduced but temporary position. In November 2020, a paper-based questionnaire was sent out to all 85 RMCs who could be identified through an internet research and to all 197 teaching practices of the Institute of General Practice and Health Services Research at the Technical University of Munich. The data analysis was descriptive and anonymised. Overall, 75 (88%) RMCs and 156 (79%) general practitioners (GPs) were included. 97% of the RMCs and 67% of the GPs assessed the introduction of RMCs in ambulatory care as reasonable, but also as an intervention concerning the self-administration of physicians (RMCs: 59% and GPs: 42%). 37% of the GPs stated that RMCs should be avoided as far as possible in future pandemic situations. Overall, GPs with more intensive contact to an RMC showed higher levels of agreement. Both groups rated the collaboration and communication strategies of politics, authorities and the Bavarian Association of Statutory Health Insurance Physicians as difficult and often contradictory. However, most of the RMCs assessed the cooperation with politics and authorities at the local level as positive. The lack of medical protective equipment at the beginning of the pandemic was judged critically by both groups of the respondents. The establishment of RMCs in the early Corona phase 2020 in Bavaria was considered sensible by almost all RMCs and the majority of the surveyed GPs. For the future, it seems necessary to involve primary care physicians more intensively and permanently in decision-making processes and to strengthen existing structures.