Real-Time Optical Tracking of Protein Corona Formation on Single Nanoparticles in Serum

The formation of a protein corona, where proteins spontaneously adhere to the surface of nanomaterials in biological environments, leads to changes in their physicochemical properties and subsequently affects their intended biomedical functionalities. Most current methods to study protein corona formation are ensemble-averaging and either require fluorescent labeling, washing steps, or are only applicable to specific types of particles. Here we introduce real-time all-optical nanoparticle analysis by scattering microscopy (RONAS) to track the formation of protein corona in full serum, at the single-particle level, without any labeling. RONAS uses optical scattering microscopy and enables real-time and in situ tracking of protein adsorption on metallic and dielectric nanoparticles with different geometries directly in blood serum. We analyzed the adsorbed protein mass, the affinity, and the kinetics of the protein adsorption at the single particle level. While there is a high degree of heterogeneity from particle to particle, the predominant factor in protein adsorption is surface chemistry rather than the underlying nanoparticle material or size. RONAS offers an in-depth understanding of the mechanisms related to protein coronas and, thus, enables the development of strategies to engineer efficient bionanomaterials.</p

Real-Time Optical Tracking of Protein Corona Formation on Single Nanoparticles in Serum

The formation of a protein corona, where proteins spontaneously adhere to the surface of nanomaterials in biological environments, leads to changes in their physicochemical properties and subsequently affects their intended biomedical functionalities. Most current methods to study protein corona formation are ensemble-averaging and either require fluorescent labeling, washing steps, or are only applicable to specific types of particles. Here we introduce real-time all-optical nanoparticle analysis by scattering microscopy (RONAS) to track the formation of protein corona in full serum, at the single-particle level, without any labeling. RONAS uses optical scattering microscopy and enables real-time and in situ tracking of protein adsorption on metallic and dielectric nanoparticles with different geometries directly in blood serum. We analyzed the adsorbed protein mass, the affinity, and the kinetics of the protein adsorption at the single particle level. While there is a high degree of heterogeneity from particle to particle, the predominant factor in protein adsorption is surface chemistry rather than the underlying nanoparticle material or size. RONAS offers an in-depth understanding of the mechanisms related to protein coronas and, thus, enables the development of strategies to engineer efficient bionanomaterials.</p

Real-Time Interfacial Nanothermometry Using DNA-PAINT Microscopy

Biofunctionalized nanoparticles are increasingly used in biomedical applications including sensing, targeted delivery, and hyperthermia. However, laser excitation and associated heating of the nanomaterials may alter the structure and interactions of the conjugated biomolecules. Currently no method exists that directly monitors the local temperature near the material's interface where the conjugated biomolecules are. Here, a nanothermometer is reported based on DNA-mediated points accumulation for imaging nanoscale topography (DNA-PAINT) microscopy. The temperature dependent kinetics of repeated and reversible DNA interactions provide a direct readout of the local interfacial temperature. The accuracy and precision of the method is demonstrated by measuring the interfacial temperature of many individual gold nanoparticles in parallel, with a precision of 1 K. In agreement with numerical models, large particle-to-particle differences in the interfacial temperature are found due to underlying differences in optical and thermal properties. In addition, the reversible DNA interactions enable the tracking of interfacial temperature in real-time with intervals of a few minutes. This method does not require prior knowledge of the optical and thermal properties of the sample, and therefore opens the window to understanding and controlling interfacial heating in a wide range of nanomaterials

Structural characterization of [M,C,2H](+) products formed by reaction of 5d metal cations Pt+ and Ir+ with ethylene oxide and Ta+ with methane using messenger spectroscopy

Structural characterization of gas-phase [M,C,2H]+(M = Ta, Ir, Pt), formed by reacting laser ablationformed M+with ethylene oxide (c-C2H4O) or methane under multiple collision conditions, is achievedusing infrared multiple-photon dissociation (IR-MPD) spectroscopy with the intracavity free-electronlaser FELICE. After product formation, part of the product distribution is complexed with Ar, allowingfor simultaneous recording of IR-MPD spectra of both bare [M,C,2H]+, which dissociates viadehydrogenation, and [M,C,2H]+∙Ar, which loses Ar. Comparison of the spectra with density functionaltheory (DFT) calculations allows for an internally consistent assignment of the spectra to the Ta+CH2(3A00) distorted carbene, Pt+CH2(2A1) carbene, and to the HIr+CH (1A0) carbyne-hydride. Evidence for asymmetric Ta+CH2∙Ar (3B2) complex is also obtained. For Pt and Ir, these structures match those foundin previous work when these species were formed by reaction of M+with methane, CH4and CD4.Under the current conditions, no clear signs of the previously observed Ir+CH2(3A2) carbene product werefound, consistent with its higher energy, especially after Ar complexation. Potential energy surfaces forthe reactions of Pt+and Ir+with c-C2H4O are also computed

A single-particle plasmon sensor to monitor proteolytic activity in real-time

We have established a label-free plasmonic platform that monitors proteolytic activity in real-time. The sensor consists of a random array of gold nanorods that are functionalized with a design peptide that is specifically cleaved by thrombin resulting in a blue-shift of the longitudinal plasmon. By monitoring the plasmon of many individual nanorods we determined thrombin’s proteolytic activity in real-time and inferred relevant kinetic parameters. Furthermore, comparison to a kinetic model revealed that the plasmon shift is dictated by a competition between peptide cleavage and thrombin binding, which have opposing effects on the measured plasmon shift. The dynamic range of the sensor is greater than two orders of magnitude, and it is capable of detecting physiologically relevant levels of active thrombin down to 3 nM in buffered conditions. We expect these plasmon-mediated label-free sensors open the window to a range of applications stretching from diagnostic and characterization of bleeding disorders to fundamental proteolytic and pharmacological studies

Stability-limited ion-exchange of calcium with zinc in biomimetic hydroxyapatite

The exchange of Ca2+ ions in hydroxyapatite (HAp) with Zn2+ ions into Zn-HAp is of interest for applications ranging from bone tissue engineering to the use as a precursor in subsequent ion-exchange reactions. Previous studies, using direct synthesis, showed that ~ 20 mol% Zn2+ ions can be incorporated into HAp, before byproducts are observed. However, this is realized at the cost of a loss in crystallinity and control over crystal size and shape with increasing amounts of Zn2+ ion incorporation. In this work a simple post-synthetic ion-exchange strategy for the formation of Zn-HAp has been investigated. By merely exposing HAp to high concentrations of zinc nitrate in water, up to 22 mol% of the Ca2+ ions can displaced by Zn2+ ions without any measured loss in crystallinity and preservation of crystallite size and shape. It was found that the incorporation of Zn2+ ions destabilizes the HAp crystals resulting in their gradual dissolution and reprecipitation. Consequently, promoting the exchange of Ca2+ with Zn2+ions using increased reaction times, sonication and increased temperature results in an increased dissolution of HAp and precipitation of hopeite crystals, thereby preventing the formation of more zinc rich Zn-HAp

Real-time Optical Tracking of Protein Corona Formation on Single Nanoparticles in Serum

Significant advances in synthesis and functionalization have provided state-of-the-art technology in controlling the physico-chemical properties of nanomaterials. These are finding numerous applications including in the biomedical field whereby nanoparticles are injected in vivo for medical imaging, theranostics and biosensing. However, interactions with proteins contained in biological fluids lead to the formation of a shell on the surface of the nanoparticles called "protein corona" (PC). PC plays a detrimental role for the intended applications as it may modify the interface of the nanoparticle and thereby block functional groups needed for recognition. It is therefore essential to understand the mechanisms of formation of these PCs in order to control the surface chemistry of the nanoparticles in complex biological fluids. Current characterization techniques can identify and quantify the composition of PCs using mass spectroscopy and electrophoresis. However, most of them do not enable real-time measurement in complex media because they require washing steps to remove excess protein. Finally, most techniques provide ensemble averages and are unable to access inter-particle heterogeneity. Here, we demonstrate the use of single-particle scattering microscopy combined with a microfluidic system to study PC formation in real-time at the single-nanoparticle level. The method is label-free and operates in undiluted blood serum. We probe PC formation on both, metallic and dielectric nanoparticles with different surface chemistries. Analysis of protein adsorption revealed unexpectedly strong heterogeneity whereby the amount of accumulated protein varies by up to a factor of 10 between the particles. Furthermore, it is found that the surface roughness of the nanoparticles affects the kinetics of the PC formation. The results of this in-situ characterization are a powerful tool to optimize the surface chemistry in order to minimize the formation of PCs and thus increase the efficiency of nanoparticles for applications such as targeted drug delivery

Real-Time Optical Tracking of Protein Corona Formation on Single Nanoparticles in Serum

The formation of a protein corona, where proteins spontaneously adhere to the surface of nanomaterials in biological environments, leads to changes in their physicochemical properties and subsequently affects their intended biomedical functionalities. Most current methods to study protein corona formation are ensemble-averaging and either require fluorescent labeling, washing steps, or are only applicable to specific types of particles. Here we introduce real-time all-optical nanoparticle analysis by scattering microscopy (RONAS) to track the formation of protein corona in full serum, at the single-particle level, without any labeling. RONAS uses optical scattering microscopy and enables real-time and in situ tracking of protein adsorption on metallic and dielectric nanoparticles with different geometries directly in blood serum. We analyzed the adsorbed protein mass, the affinity, and the kinetics of the protein adsorption at the single particle level. While there is a high degree of heterogeneity from particle to particle, the predominant factor in protein adsorption is surface chemistry rather than the underlying nanoparticle material or size. RONAS offers an in-depth understanding of the mechanisms related to protein coronas and, thus, enables the development of strategies to engineer efficient bionanomaterials

Organizational Culture and Relationship Skills

While both the strategic management and the network literature recognize the importance of inter-firm relationships for explaining competitive advantage, the question why firms differ in their ability to benefit from these relationships is rarely addressed.This paper aims to begin to fill this gap in the literature. We argue that organizational culture is an important factor influencing the relationship skills of a firm, defined as a firm s ability to manage its ties with other firms, whether these are customers, suppliers, or service providers. We assume relationship skills to be especially relevant for the formation and maintenance of close and durable transaction ties.We test our model on a dataset of 127 Dutch inter-firm relations and find general support.Specifically, we find that firms with organizational cultures characterized by an orientation towards stability and predictability, a positive orientation towards innovation, and not characterized by a strong focus on immediate results, score high on relationship skills.Relationship skills, in turn, are found to have a positive influence on the outcomes of inter-firm relationships in terms of learning, achieving innovations and gaining new contacts, but not in terms of immediate (financial) results.