Modelling the influence of UV curing strategies for optimisation of inkjet based 3D printing

A predictive model is developed to assist in the design and manufacture of structures by inkjet based 3D printing (IJ3DP)/additive manufacturing. IJ3DP often exploits photopolymerisation to rapidly convert a photoreactive liquid ink into a solid product. Unfortunately, deviations from the intended design and product performance are often observed and a lack of understanding of the underlying processes and their interactions prevents users from resolving these issues. We develop and validate a predictive model that incorporates the critical processing parameters, including UV source pathway, UV intensity, printing strategy, and interlayer attenuation, such that we are able to predict the degree of ink conversion throughout the product. We show how this model can then be used to guide users by demonstrating the coupling of this description with a cost model and illustrating how printing strategy affects descriptors of both the quality and cost of production

Modulating the biological function of protein by tailoring the adsorption orientation on nanoparticles

Protein orientation in nanoparticle-protein conjugates plays a crucial role in binding to cell receptors and ultimately, defines their targeting efficiency. Therefore, understanding fundamental aspects of the role of protein orientation upon adsorption on the surface of nanoparticles (NPs) is vital for the development of clinically important protein-based nanomedicines. In this work, new insights on the effect of the different orientation of cytochrome c (cyt c) bound to gold nanoparticles (GNPs) using various ligands on its apoptotic activity is reported. Time-of-Flight Secondary-Ion Mass Spectrometry (ToF-SIMS), electrochemical and circular dichroism (CD) analyses are used to investigate the characteristics of cyt c orientation and structure on functionalized GNPs. These studies indicate that the orientation and position of the heme ring inside the cyt c structure can be altered by changing the surface chemistry on the GNPs. A difference in the apoptosis inducing capability because of different orientation of cyt c bound to the GNPs is observed. These findings indicate that the biological activity of a protein can be modulated on the surface of NPs by varying its adsorption orientation. This study will impact on the rational design of new nanoscale biosensors, bioelectronics, and nanoparticle-protein based drugs

Pancreatic resections : experience of the pancreato-biliary group at Hospital de Clínicas de Porto Alegre, Brazil, between 2000 and 2003

Este trabalho apresenta a experiência de 20 ressecções pancreáticas e tem como objetivo principal ressaltar a importância dos centros de referência para doenças de tratamento cirúrgico complexo, como é o caso dos portadores de neoplasia da confluência biliopancreática. De 60 doentes com neoplasia biliopancreática tratados no período de janeiro de 2000 a janeiro de 2003, 20 foram submetidos a ressecção: 16 a duodenopancreatectomia, três a ressecção corpo-caudal e um a ressecção da papila de Vater. As complicações mais freqüentes foram: cinco fístulas pancreáticas, sete abscessos intra-abdominais e oito infecções do aparelho respiratório. A mortalidade foi de 0%. Nos Estados Unidos, em hospitais com pequena experiência, nos anos de 1984 a 1991, a mortalidade foi de 21,8%; já em centros de referência, foi de 4%. Em série anterior do Hospital de Clínicas de Porto Alegre, referente ao período de 1988 a 1999, a mortalidade foi de 20%. A presente série confirma a experiência internacional: o resultado das ressecções pancreáticas é melhor em centros de referência. A indicação da cirurgia, os cuidados pré e pós-operatórios e a experiência de uma equipe que realiza o procedimento no mínimo de 10 a 15 vezes por ano são fundamentais para a obtenção de bons resultados, com a gradativa diminuição do tempo de internação e dos custos hospitalares.This paper presents the experience of 20 pancreatic resections. The main purpose of the study was to emphasize the importance of high-volume hospitals to improve results with complex surgery procedures such as pancreaticoduodenectomies. Out of 60 patients with periampullary neoplasia treated from January 2000 to January 2003, 20 underwent resections: 16 pancreaticoduodenectomies, three body and tail pancreatectomies, and one local excision of the Vater’s ampulla. The most frequent complications were five pancreatic fistulae, seven intra-abdominal abscesses and eight respiratory tract infections. In this series, mortality was 0%. In previous studies carried out in the United States (1984 to 1991), mortality has been reported to reach21.8% in minimal-volume hospitals, against 4% in high-volume hospitals. In addition, in a previous series from Hospital de Clínicas de Porto Alegre (1988 to 1999), mortality was 20%. The experience described in this study confirms that pancreatic resections have better results when performed in high-volume centers. The correct indication of surgery, pre and postoperative care and the experience of a surgical staff that carries out at least 10 to 15 resections per year, are of paramount importance for obtaining good results, with a gradual decrease in hospital stay and related costs

Protein identification by 3D OrbiSIMS to facilitate in situ imaging and depth profiling

Label-free protein characterization at surfaces is commonly achieved using digestion and/or matrix application prior to mass spectrometry. We report the assignment of undigested proteins at surfaces in situ using secondary ion mass spectrometry (SIMS). Ballistic fragmentation of proteins induced by a gas cluster ion beam (GCIB) leads to peptide cleavage producing fragments for subsequent OrbitrapTM analysis. In this work we annotate 16 example proteins (up to 272 kDa) by de novo peptide sequencing and illustrate the advantages of this approach by characterizing a protein monolayer biochip and the depth distribution of proteins in human skin

The influence of printing parameters on multi-material two-photon polymerisation based micro additive manufacturing

Two-photon polymerisation (2PP) based additive manufacturing has emerged as a powerful technology to fabricate complex three-dimensional micro- and nanoscale architectures. However, a comprehensive understanding of the effect of printing parameters on the functional properties of these structures is needed to unleash the potential of 2PP and enable controlled deposition / integration of various materials into multi-material structures. In this study we investigate the correlation between printing parameters, resin composition and the final properties of 2PP structures fabricated with different monomers and initiators. The link between 2PP process and final material properties is validated by morphological studies, vibrational spectroscopy and advanced mass spectrometry, ToF-SIMS, imaging. We establish empirical relationships between printing parameters and mechanical properties, and achieve controlled deposition of different monomers with high precision and uniform composition. The approaches developed here are successfully used to demonstrate multi-material 2PP and produce complex 3D architectures incorporating three polymers. The 2PP structures produced can be transferred into solution or onto different substrates, in addition to direct fabrication on flexible substrates. This work advances the understanding of the 2PP process, which enable rational design and manufacture of complex geometries and additive manufacturing of nanoscale multi-material structures

Strategies for Integrating Metal Nanoparticles with Two-Photon Polymerization Process: Toward High Resolution Functional Additive Manufacturing

This study reports the successful fabrication of complex 3D metal nanoparticle–polymer nanocomposites using two-photon polymerization (2PP). Three complementary strategies are detailed: in situ formation of metal nanoparticles (MeNPs) through a single-step photoreduction process, integration of pre-formed MeNPs into 2PP resin, and site-selective MeNPs decoration of 3D 2PP structures. In the in situ formation strategy, a phase-transfer method is applied to transfer silver and copper ions from an aqueous phase into a toluene solvent to disperse them in photoreactive monomers.The addition of a photosensitive dye, coumarin 30, facilitated the reduction of silver ions and improved the distribution of silver nanoparticles (AgNPs). This strategy is successfully used to produce other MeNPs, such as Cu and Au. The integration of pre-formed MeNPs enabled highly controlled NP size distribution within the 2PP 3D structures with high-fidelity To enable selective decoration of 2PP 3D surfaces with MeNPs, a multimaterial strategy is developed, with one of the resins designed for thiol-ene reaction, which demonstrated selective binding to AuNPs. The successful development of complementary strategies for integration of MeNPs into 2PP resins offers exciting opportunities for fabrication of MeNP composites with sub-micron resolution for applications fromphotonics to metamaterials and drug delivery