Protein-nanoparticle construct for intracellular delivery

Proteins are essential parts of organisms and participate in virtually every process within cells. Being able to control them, deliver them to specific locations or give them desired functionalities and properties pave the way to numerous applications, including use as biosensors, within biocatalysis and biomedical devices. Thus, protein monitoring is extremely relevant and one of the most important challenges in biotechnology. One way to protein monitoring could be related to understanding and controlling their tertiary structure. It is known that the properties and functions of proteins are determined by their conformation. Therefore being able to induce conformational changes in proteins may be a possible way to control them. In the present study, a series of experiments with Bovine serum albumin (BSA) were performed, analyzed and described to understand the adsorption, unfolding behaviour and conformational changes in tertiary structure of this protein when it was attached and spread on the surface of different types of polymer nanoparticles. BSA was selected since it is wellstudied protein, the most abundant protein in plasma and one of the most used model protein. Three kinds of negatively charged monodisperse polymer nanoparticles were elaborated by soap free emulsion polymerization: two different size polymer nanoparticles with epoxy groups and one type of polymer nanoparticles without epoxy groups. Finally, size and zeta potential measurements of corresponding BSA-polymer nanoparticle constructs, fluorescence spectroscopy, isothermal titration calorimetry (ITC) and unfolding studies with urea were carried out to study BSA conformational isomerisation in immobilized polymer nanoparticle systems. All experiments were done at three different pH conditions; 3.8, 7.4 and 9, corresponding to conditions below and above the isoelectric point (pI) of BSA. BSA immobilization and degree of unfolding was found to be strongly affected by pH and matching of the global protein and polymer nanoparticle charges. The results suggested that polymer nanoparticles with epoxy groups offered covalent binding with stronger attachment and larger conformational isomerisation than polymer nanoparticles without epoxy groups. These changes occurred to the largest degree at pH 7.4. This may be due to a high number of epoxy groups conjugated with amino groups of the protein. At pH 3.8 it seemed that the attachment of BSA was highest but without relevant structural alterations while at pH 9 it was in an intermediate level of adsorption and structural changes. Finally, there were no appreciable discrepancies between different size polymer nanoparticles.Outgoin

Size-dependent protein-nanoparticle interactions in citrate-stabilized gold nanoparticles : the emergence of the protein corona

Surface modifications of highly monodisperse citrate-stabilized gold nanoparticles (AuNPs) with sizes ranging from 3.5 to 150 nm after their exposure to cell culture media supplemented with fetal bovine serum were studied and characterized by the combined use of UV-vis spectroscopy, dynamic light scattering, and zeta potential measurements. In all the tested AuNPs, a dynamic process of protein adsorption was observed, evolving toward the formation of an irreversible hard protein coating known as Protein Corona. Interestingly, the thickness and density of this protein coating were strongly dependent on the particle size, making it possible to identify different transition regimes as the size of the particles increased: (i) NP-protein complexes (or incomplete corona), (ii) the formation of a near-single dense protein corona layer, and (iii) the formation of a multilayer corona. In addition, the different temporal patterns in the evolution of the protein coating came about more quickly for small particles than for the larger ones, further revealing the significant role that size plays in the kinetics of this process. Since the biological identity of the NPs is ultimately determined by the protein corona and different NP-biological interactions take place at different time scales, these results are relevant to biological and toxicological studies

Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments : Aggregation, Dissolution and Oxidation

Herein, we study how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution. The optical contributions of these processes to the extinction spectra in the UV-vis region are often overlapped, making difficult its interpretation. In this regard, modeling the UV-vis spectra (in particular absorbance curve, peaks position, intensity and full width at half maximum-FWHM) of each process separately offers a powerful tool to identify the transformation of NPs under relevant and complex scenarios, such as in biological media. The proper identification of these transformations is crucial to understand the biological effects of the NPs

Energy management, wireless and system solutions for highly integrated implantable devices

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The Normative Implication of the B Corp Movement in the Business and Human Rights Context (abstract)

Over the past decades, issues of corporate accountability and social responsibility have risen to the forefront of international debate. The U.N. Guiding Principles on Business and Human Rights (Guiding Principles), endorsed by the U.N. HRC in June 2011, lays out authoritatively the state duty to protect and the corporate responsibility to respect human rights. In an effort to operationalize the Guiding Principles, the U.N. Working Group on Business and Human Rights has called on all states to develop a National Action Plan (NAP) regarding domestic implementation of the Guiding Principles. A key first-step in the creation of a NAP is the completion of a national baseline assessment, a taking of stock of the current conditions affecting the protection and promotion of human rights by the state and businesses alike. With over twenty-five countries now committed to the creation of a NAP, it is increasingly important to evaluate the existing corporate landscape, specifically structures that claim to be socially and ethically motivated. The B Corp movement began in 2006, through the work of California based non-profit B-Lab. A B Corp is a business certified by B-Lab as committed to creating and supporting social and environmental rights. The B Corp movement has grown in size and stature, spreading into over thirty countries and garnering a reputation for excellence. Boosts to the movement have recently come from the certification of large multinational companies, and the interest of others that followed. As the B Corp movement continues to proliferate, it’s normative value on the business and human rights field merits analysis. What are the normative implications of the B Corp movement?—Is it a tool that should be embraced by business and human rights activists or one that undermines the movement by enabling corporations to claim an inability to take into account ethical considerations without adoption of a special corporate form

Analysis of uncertainty and variability in finite element computational models for biomedical engineering: characterization and propagation

Computational modeling has become a powerful tool in biomedical engineering thanks to its potential to simulate coupled systems. However, real parameters are usually not accurately known, and variability is inherent in living organisms. To cope with this, probabilistic tools, statistical analysis and stochastic approaches have been used. This article aims to review the analysis of uncertainty and variability in the context of finite element modeling in biomedical engineering. Characterization techniques and propagation methods are presented, as well as examples of their applications in biomedical finite element simulations. Uncertainty propagation methods, both non-intrusive and intrusive, are described. Finally, pros and cons of the different approaches and their use in the scientific community are presented. This leads us to identify future directions for research and methodological development of uncertainty modeling in biomedical engineering

Computational evaluation of cochlear implant surgery outcomes accounting for uncertainty and parameter variability

Cochlear implantation (CI) is a complex surgical procedure that restores hearing in patients with severe deafness. The successful outcome of the implanted device relies on a group of factors, some of them unpredictable or difficult to control. Uncertainties on the electrode array position and the electrical properties of the bone make it difficult to accurately compute the current propagation delivered by the implant and the resulting neural activation. In this context, we use uncertainty quantification methods to explore how these uncertainties propagate through all the stages of CI computational simulations. To this end, we employ an automatic framework, encompassing from the finite element generation of CI models to the assessment of the neural response induced by the implant stimulation. To estimate the confidence intervals of the simulated neural response, we propose two approaches. First, we encode the variability of the cochlear morphology among the population through a statistical shape model. This allows us to generate a population of virtual patients using Monte Carlo sampling and to assign to each of them a set of parameter values according to a statistical distribution. The framework is implemented and parallelized in a High Throughput Computing environment that enables to maximize the available computing resources. Secondly, we perform a patient-specific study to evaluate the computed neural response to seek the optimal post-implantation stimulus levels. Considering a single cochlear morphology, the uncertainty in tissue electrical resistivity and surgical insertion parameters is propagated using the Probabilistic Collocation method, which reduces the number of samples to evaluate. Results show that bone resistivity has the highest influence on CI outcomes. In conjunction with the variability of the cochlear length, worst outcomes are obtained for small cochleae with high resistivity values. However, the effect of the surgical insertion length on the CI outcomes could not be clearly observed, since its impact may be concealed by the other considered parameters. Whereas the Monte Carlo approach implies a high computational cost, Probabilistic Collocation presents a suitable trade-off between precision and computational time. Results suggest that the proposed framework has a great potential to help in both surgical planning decisions and in the audiological setting process