Hyperbranched DNA clusters

Taking advantage of the base-pairing specificity and tunability of DNA interactions, we investigate the spontaneous formation of hyperbranched clusters starting from purposely designed DNA tetravalent nanostar monomers, encoding in their four sticky-ends the desired binding rules. Specifically, we combine molecular dynamics simulations and Dynamic Light Scattering experiments to follow the aggregation process of the DNA nanostars at different concentrations and temperatures. At odd with the Flory-Stockmayer predictions, we find that, even when all possible bonds are formed, the system does not reach percolation due to the presence of intracluster bonds. We present an extension of the Flory-Stockmayer theory that properly describes the numerical and the experimental results.Comment: The Supplementary Information is included in the pdf fil

Photonic simulation of entanglement growth and engineering after a spin chain quench

The time evolution of quantum many-body systems is one of the most important processes for benchmarking quantum simulators. The most curious feature of such dynamics is the growth of quantum entanglement to an amount proportional to the system size (volume law) even when interactions are local. This phenomenon has great ramifications for fundamental aspects, while its optimisation clearly has an impact on technology (e.g., for on-chip quantum networking). Here we use an integrated photonic chip with a circuit-based approach to simulate the dynamics of a spin chain and maximise the entanglement generation. The resulting entanglement is certified by constructing a second chip, which measures the entanglement between multiple distant pairs of simulated spins, as well as the block entanglement entropy. This is the first photonic simulation and optimisation of the extensive growth of entanglement in a spin chain, and opens up the use of photonic circuits for optimising quantum devices

Cold-swappable DNA gels

We report an experimental investigation of an all-DNA gel composed by tetra-functional DNA nanoparticles acting as network nodes and bi-functional ones acting as links. The DNA binding sequence is designed to generate at room and lower temperatures a persistent long-lived network. Exploiting ideas from DNA-nanotechnology, we implement in the binding base sequences an appropriate exchange reaction which allows links to swap, constantly retaining the total number of network links. The DNA gel is thus able to rearrange its topology at low temperature while preserving its fully-bonded configuration

Surface-Enhanced Raman Scattering of DNA-Nanoparticle assemblies

During the last years, soft matter colloids have gained important achievements and a large amount of results have been accomplished to the realisation of innovative and smart nanomaterials. In particular, the understanding in the mastering of DNA-nanoparticle systems, which combine the plasmonic properties of metallic nanoparticles (NPs) with the programmability and self-assembly of DNA strands – opens up a great number of applications in different branches of science, especially in nanoscience. Consequently, the importance of Surface Enhanced Raman Scattering (SERS), which associates a high sensitivity and a specific spectral signature of DNA, is significantly increasing in the detection of specific targets, thus, in the implementation of high-quality biosensors. The DNA base-pairing specificity (A-T, C-G) allows the breakthrough in “programmable bonds” between nanoparticles, serving as the basic building blocks for the creation of mesoscopic plasmonic aggregates. In our labs we provided to the realisation of DNA-NP structures by properly functionalizing metallic gold NPs with complementary and purposely programmed single-stranded DNA. To this aim, we have chosen two specific single-stranded DNA sequences, consisting of 12 base oligomers, with a thiolgroup at the end of each one which allows to covalent bond onto the metallic NP surfaces; the aforementioned sequence assures not only a harder and more reproducible bond but also a more controllable adherence. Therefore, it has been possible an ensuing study of the spectroscopic features of these binary systems through the use of SERS. We have thus characterised the SERS spectrum for both DNA sequences-which were attached on gold NPs and obtained a coherent and reproducible signal. The spectra were obtained by using a direct and label-free protocol, thus, avoiding the loss of information about the intrinsic chemical and structural properties of DNA oligonucleotides that fluorescence methods cause. In addition, we provided the realisation of DNA-nanoparticle aggregates, starting from gold nanoparticles functionalized with the two different 12-base DNA sequences and let them hybridise through the addition of a DNA ‘bridge’ which is a 24 base oligomers complementary to the two chains

Exploiting SERS sensitivity to monitor DNA aggregation properties

In the last decades. DNA has been considered far more than the system carrying the essential genetic instructions. Indeed, because of the remarkable properties of the base-pairing specificity and thermoreversibility of the interactions, DNA plays a central role in the design of innovative architectures at the nanoscale. Here, combining complementary DNA strands with a custom-made solution of silver nanoparticles, we realize plasmonic aggregates to exploit the sensitivity of Surface Enhanced Raman Spectroscopy (SERS) for the identification/detection of the distinctive features of DNA hybridization, both in solution and on dried samples. Moreover. SERS allows monitoring the DNA aggregation process by following the temperature variation of a specific spectroscopic marker associated with the Watson-Crick hydrogen bond formation. This temperature-dependent behavior enables us to precisely reconstruct the melting profile of the selected DNA sequences by spectroscopic measurements only. (C) 2020 Elsevier B.V. All rights reserved

Treatment of kidney clear cell carcinoma, lung adenocarcinoma and glioblastoma cell lines with hydrogels made of DNA nanostars

Overcoming the systemic administration of chemotherapy to reduce drug toxicity and the application of personalised medicine are two of the major challenges in the treatment of cancer. To this aim, efforts are focused on finding novel nanomaterials for the targeted administration of drugs and bioactive molecules in the tumor sites. DNA-based hydrogels are promising candidates for these applications. However, while such materials are fairly known from a structural and physical standpoint, their effects on cell cultures are far less investigated. Here, we studied the biological response of three different cell lines (clear cell renal cell carcinoma 786-O, lung adenocarcinoma H1975 and glioblastoma U87MG) to the treatment with DNA-GEL - a DNA-based hydrogel composed of interacting DNA nanostars. Additionally, we investigated the structural modification of DNA-GELs under cell culture conditions. The results we collected show a cell type specificity of the response, with interesting implications for future applications

Quantum simulation of spin chain dynamics via integrated photonics

Summary form only given. Photonic circuits represent a promising platform to perform quantum simulation of several different physical phenomena. Indeed, large progresses have been achieved in the last few years due to the technological advances enabled by integrated photonics, which allowed to achieve a significant increase in the size of the implemented systems. Notable examples of observed phenomena in integrated circuits include Anderson localization [1] and transport mechanisms [2].[4]). We discuss the photonic simulation of spin chain dynamics after a quench in a 5-site system [3]. Such dynamics present the feature of entangling distant spins in pairs starting from the input (separable) Neel state, thus obtaining an amount of entanglement which is proportional to the number of sites present in the system (volume law [4]). The verification of such increase in the amount of the generated entanglement provides a useful resource for several quantum information protocols, including quantum teleportation and quantum networking

Quantum simulation of spin chain dynamics via integrated photonics

Summary form only given. Photonic circuits represent a promising platform to perform quantum simulation of several different physical phenomena. Indeed, large progresses have been achieved in the last few years due to the technological advances enabled by integrated photonics, which allowed to achieve a significant increase in the size of the implemented systems. Notable examples of observed phenomena in integrated circuits include Anderson localization [1] and transport mechanisms [2].[4]). We discuss the photonic simulation of spin chain dynamics after a quench in a 5-site system [3]. Such dynamics present the feature of entangling distant spins in pairs starting from the input (separable) Neel state, thus obtaining an amount of entanglement which is proportional to the number of sites present in the system (volume law [4]). The verification of such increase in the amount of the generated entanglement provides a useful resource for several quantum information protocols, including quantum teleportation and quantum networking

Photonic simulation of entanglement generation and transfer in a spin chain

We report on photonic quantum simulation of a 5-site spin chain dynamics in femtosecond-written circuits, with engineered couplings for perfect quantum transport, confirming the expected creation of entanglement at half transport time

A experiência do adoecer: uma discussão sobre saúde, doença e valores

Partindo de uma discussão do conceito de saúde-doença, percebe-se que um dos enfoques atuais inclui a percepção do sujeito quanto à sua condição. Porém, a hegemonia de um método clínico que, muitas vezes, não considera esta individualidade levou alguns profissionais a discutir as necessidades de mudanças na abordagem médica. Por meio da discussão do caso relatado, percebemos que a relação médico-paciente influencia direta ou indiretamente a satisfação, o estado de saúde do paciente e a qualidade dos serviços de saúde. O cuidado efetivo requer um olhar atento às reais necessidades do paciente e respeito às suas opiniões sobre o adoecimento, suas percepções e sua cultura. A Medicina Centrada na Pessoa é um método clínico que propõe uma abordagem médica que possibilita o atendimento integral e humanístico e respeita a autonomia das pessoas