Poly(dehydroalanine)-Based Hydrogels as Efficient Soft Matter Matrices for Light-Driven Catalysis.

Soft matter integration of photosensitizers and catalysts provides promising solutions to developing sustainable materials for energy conversion. Particularly, hydrogels bring unique benefits, such as spatial control and 3D-accessibility of molecular units, as well as recyclability. Herein, the preparation of polyampholyte hydrogels based on poly(dehydroalanine) (PDha) is reported. Chemically crosslinked PDha with bis-epoxy poly(ethylene glycol) leads to a transparent, self-supporting hydrogel. Due to the ionizable groups on PDha, this 3D polymeric matrix can be anionic, cationic, or zwitterionic depending on the pH value, and its high density of dynamic charges has a potential for electrostatic attachment of charged molecules. The integration of the cationic molecular photosensitizer [Ru(bpy)3 ]2+ (bpy = 2,2'-bipyridine) is realized, which is a reversible process controlled by pH, leading to light harvesting hydrogels. They are further combined with either a thiomolybdate catalyst ([Mo3 S13 ]2- ) for hydrogen evolution reaction (HER) or a cobalt polyoxometalate catalyst (Co4 POM = [Co4 (H2 O)2 (PW9 O34 )2 ]10- ) for oxygen evolution reaction (OER). Under the optimized condition, the resulting hydrogels show catalytic activity in both cases upon visible light irradiation. In the case of OER, higher photosensitizer stability is observed compared to homogeneous systems, as the polymer environment seems to influence decomposition pathways.

Thiomolybdate Clusters: From Homogeneous Catalysis to Heterogenization and Active Sites.

Thiomolybdates are molecular molybdenum-sulfide clusters formed from Mo centers and sulfur-based ligands. For decades, they have attracted the interest of synthetic chemists due to their unique structures and their relevance in biological systems, e.g., as reactive sites in enzymes. More recently, thiomolybdates are explored from the catalytic point of view and applied as homogeneous and molecular mimics of heterogeneous molybdenum sulfide catalysts. This review summarizes prominent examples of thiomolybdate-based electro- and photocatalysis and provides a comprehensive analysis of their reactivities under homogeneous and heterogenized conditions. Active sites of thiomolybdates relevant for the hydrogen evolution reaction are examined, aiming to shed light on the link between cluster structure and performance. The shift from solution-phase to surface-supported thiomolybdates is discussed with a focus on applications in electrocatalysis and photocatalysis. The outlook highlights current trends and emerging areas of thiomolybdate research, ending with a summary of challenges and key takeaway messages based on the state-of-the-art research.

Stress and heat flux via automatic differentiation.

Machine-learning potentials provide computationally efficient and accurate approximations of the Born-Oppenheimer potential energy surface. This potential determines many materials properties and simulation techniques usually require its gradients, in particular forces and stress for molecular dynamics, and heat flux for thermal transport properties. Recently developed potentials feature high body order and can include equivariant semi-local interactions through message-passing mechanisms. Due to their complex functional forms, they rely on automatic differentiation (AD), overcoming the need for manual implementations or finite-difference schemes to evaluate gradients. This study discusses how to use AD to efficiently obtain forces, stress, and heat flux for such potentials, and provides a model-independent implementation. The method is tested on the Lennard-Jones potential, and then applied to predict cohesive properties and thermal conductivity of tin selenide using an equivariant message-passing neural network potential.

Multimodal Analysis of Light-Driven Water Oxidation in Nanoporous Block Copolymer Membranes.

Heterogeneous light-driven catalysis is a cornerstone of sustainable energy conversion. Most catalytic studies focus on bulk analyses of the hydrogen and oxygen evolved, which impede the correlation of matrix heterogeneities, molecular features, and bulk reactivity. Here, we report studies of a heterogenized catalyst/photosensitizer system using a polyoxometalate water oxidation catalyst and a model, molecular photosensitizer that were co-immobilized within a nanoporous block copolymer membrane. Via operando scanning electrochemical microscopy (SECM), light-induced oxygen evolution was determined using sodium peroxodisulfate (Na2 S2 O8 ) as sacrificial electron acceptor. Ex situ element analyses provided spatially resolved information on the local concentration and distribution of the molecular components. Infrared attenuated total reflection (IR-ATR) studies of the modified membranes showed no degradation of the water oxidation catalyst under the reported light-driven conditions.

Hetero-Diels-Alder Cycloaddition with RAFT Polymers as Bioconjugation Platform.

We introduce the bioconjugation of polymers synthesized by RAFT polymerization, bearing no specific functional end group, by means of hetero-Diels-Alder cycloaddition through their inherent terminal thiocarbonylthio moiety with a diene-modified model protein. Quantitative conjugation occurs over the course of a few hours, at ambient temperature and neutral pH, and in the absence of any catalyst. Our technology platform affords thermoresponsive bioconjugates, whose aggregation is solely controlled by the polymer chains.

α,ω-Reactive Building Blocks Based on a Dual Functional RAFT Agent for Thermal and Light-Induced Ligation.

A dual functional chain transfer agent (CTA) capable of highly efficient sequential thermal and photoinduced ligation, generating α,ω-functional polymers, is introduced. The newly designed CTA (1-(4-((2-formyl-3-methyl phenoxy)methyl)phenyl)ethyl (diethoxyphosphoryl)methane dithioate) fuses thermally triggered hetero Diels-Alder chemistry with rapid light-induced photoenol chemistry. The versatility of the CTA is exemplarily demonstrated via the preparation of an amphiphilic triblock quaterpolymer poly(isoprene-co-styrene)-block-poly(ethyl acrylate)-block-poly(ethylene oxide) (P(I-co-S)-b-PEA-b-PEO). Subsequent to the homopolymerization of ethyl acrylate (PEA), a Cp-functional poly(isoprene-co-styrene) (P(I-co-S)) is conjugated with the electron-deficient C═S double bond (dienophile) of the CTA end group, generating a P(I-co-S)-b-PEA diblock terpolymer. The triblock quaterpolymer P(I-co-S)-b-PEA-b-PEO is generated by photoligation of a macromolecular dienophile, i.e., the fumarate-terminated poly(ethylene oxide) (PEO-fum) to the photoenol-functional P(I-co-S)-b-PEA. The new dual functional ligation RAFT agent constitutes a technology platform for generating α,ω-reactive building blocks from one single chain transfer agent.

Fast and Simple Preparation of Patterned Surfaces with Hydrophilic Polymer Brushes by Micromolding in Capillaries.

Micropatterns of hydrophilic polymer brushes were prepared by micromolding in capillaries (MIMIC). The polymers are covalently bound to the surfaces by a rapid hetero Diels-Alder reaction, constituting the first example of polymers grafted to surfaces in a defined pattern by MIMIC. The polymers [poly(acrylic acid), poly(hydroxyethyl acrylate), and poly(tetraethylene glycol acrylate) ranging in molecular weight from 1500 to 6000 g mol(-1)] were prepared with narrow dispersities via the reversible addition-fragmentation chain transfer (RAFT) process using a highly electron deficient RAFT agent that can react with surface-anchored dienes such as cyclopentadiene. We demonstrate that the anchoring method is facile to perform and highly suitable for preparing patterned surfaces that are passivated against biological impact in well-defined areas.

Vena cava filters in cancer patients: experience with 50 patients.

OBJECTIVE: To study the immediate and late results obtained from the implantation of vena cava filters in cancer patients with deep vein thrombosis concomitant with neoplasia. METHODS: This was a retrospective evaluation of 50 patients with an association of cancer and deep venous thrombosis who underwent interruption of the inferior vena cava and the insertion of permanent vena cava filters. The indications for the procedure, filter implantation technique, early and late complications related to the operation, and the clinical evolution were evaluated. RESULTS: The most frequent indication for filter implantation was the contraindication for full anticoagulant treatment (80%). The femoral vein was the preferred access route (86% of the patients). There were no complications related to the surgical procedure. During the follow-up, the following complications were observed: 1 episode of nonfatal pulmonary thromboembolism, 2 cases of occlusion of the inferior vena cava, and 1 case of thrombus retained in the device. Twenty patients (40%) died due to progression of the neoplasm. CONCLUSIONS: Interruption of the inferior cava vein using an endoluminal filter is a procedure with a low rate of complications. It is a safe and efficient measure for preventing pulmonary embolism in cancer patients who have deep vein thrombosis of the lower limbs.

Vena cava filters in cancer patients: experience with 50 patients

OBJETIVO: Estudar os resultados imediatos e tardios obtidos com a implantação de filtros de veia cava inferior em pacientes com trombose venosa profunda concomitante a neoplasia. MÉTODOS: Avaliamos retrospectivamente 50 pacientes com câncer e trombose venosa profunda associada submetidos a interrupção de veia cava inferior com filtros intraluminais definitivos. Foram estudados aspectos referentes à indicação do procedimento, à técnica de implante dos dispositivos, complicações precoces e tardias relacionadas à operação e à evolução dos pacientes. RESULTADOS: A indicação mais freqüente para o procedimento foi a impossibilidade de anticoagulação plena (80% ) e a via de acesso preferencial foi a punção da veia femoral, realizada em 86% dos pacientes. Não houve complicações relativas ao implante dos filtros. Durante a evolução ocorreram: um episódio de tromboembolia pulmonar não fatal e dois casos de oclusão da veia cava inferior; em um paciente foi demonstrada a presença de coágulo retido no dispositivo. Vinte pacientes (40%) faleceram devido à neoplasia.CONCLUSÃO: A interrupção da veia cava inferior com filtro endoluminal é um procedimento com baixo índice de complicações e eficaz na prevenção da embolia pulmonar nos pacientes com tromobose venosa profunda de membros inferiores portadores de câncer.

Totally implantable venous catheters for chemotherapy: experience in 500 patients.

CONTEXT: Totally implantable devices are increasingly being utilized for chemotherapy treatment of oncological patients, although few studies have been done in our environment to analyze the results obtained from the implantation and utilization of such catheters. OBJECTIVE: To study the results obtained from the implantation of totally implantable catheters in patients submitted to chemotherapy. TYPE OF STUDY: Prospective. SETTING: Hospital do Cancer A.C. Camargo, Sao Paulo, Brazil. METHODS: 519 totally implantable catheters were placed in 500 patients submitted to chemotherapy, with preference for the use of the right external jugular vein. Evaluations were made of the early and late-stage complications and patient evolution until removal of the device, death or the end of the treatment. RESULTS: The prospective analysis showed an average duration of 353 days for the catheters. There were 427 (82.2%) catheters with no complications. Among the early complications observed, there were 15 pathway hematomas, 8 cases of thrombophlebitis of the distal stump of the external jugular vein and one case of pocket infection. Among the late-stage complications observed, there were 43 infectious complications (0.23/1000 days of catheter use), 11 obstructions (0.06/1000 days of catheter use) and 14 cases of deep vein thrombosis (0.07/1000 days of catheter use). Removal of 101 catheters was performed: 35 due to complications and 66 upon terminating the treatment. A total of 240 patients died while the catheter was functioning and 178 patients are still making use of the catheter. CONCLUSION: The low rate of complications obtained in this study confirms the safety and convenience of the use of totally implantable accesses in patients undergoing prolonged chemotherapy regimes.

Totally implantable venous catheters for chemotherapy: experience in 500 patients

CONTEXTO: Os dispositivos totalmente implantáveis vêm sendo cada vez mais utilizados para quimioterapia de pacientes oncológicos, porém poucos são os estudos em nosso meio que analisam os resultados obtidos com a implantação e utilização desses cateteres. OBJETIVO: Estudar os resultados obtidos com a implantação de cateteres totalmente implantáveis em pacientes submetidos a quimioterapia. TIPO DO ESTUDO: Prospectivo. LOCAL: Hospital do Câncer A.C. Camargo, São Paulo, Brasil. MÉTODOS: Foram colocados 519 cateteres totalmente implantáveis em 500 pacientes a serem submetidos a regime de quimioterapia preferencialmente utilizando-se a veia jugular externa direita. Foram avaliadas as complicações precoces, as tardias e a evolução até a retirada do dispositivo, morte ou fim de tratamento. RESULTADOS: A análise prospectiva mostrou duração média dos cateteres de 353 dias. Em 427 (82,2%) cateteres não se observou nenhuma complicação. Entre as complicações precoces, observamos 15 hematomas de trajeto, oito tromboflebites de coto distal de veia jugular externa e uma infecção de bolsa de subcutâneo. Entre as complicações tardias, observamos 43 complicações infecciosas (0,23/1000 dias de uso de cateter), 11 obstruções (0,06/1000 dias de uso de cateter) e 14 tromboses venosas profundas (0,07/1000 dias de uso de cateter). Foram retirados 101 cateteres, 35 devido às complicações e 66 por final de tratamento. 240 pacientes foram a óbito com o cateter funcionante e 178 pacientes ainda o utilizavam para quimioterapia. CONCLUSAO: As baixas taxas de complicação obtidas nesse estudo confirmam a segurança e conveniência do uso dos acessos totalmente implantáveis em pacientes em regime prolongado de quimioterapia.

Cateteres venosos totalmente implantáveis para quimioterapia: experiência em 415 pacientes / Totally implantable venous catheters for chemotherapy: experience in 415 patients

Introdução: Os dispositivos totalmente implantáveis vem sendo cada vez mais utilizados para quimioterapia de pacientes oncológicos porém poucos são os estudos em nosso meio que analisam os resultados obtidos com o implante e utilização desses cateteres. Material e Métodos: foram colocados 430 cateteres totalmente implantáveis em 415 pacientes a serem submetidos a regime de quimioterapia preferencialmente utilizando-se a veia jugular externa direita. Foram avaliadas as complicações precoces, as tardias e a evolução até a retidada do dispositivo, morte ou fim do tratamento. Resultados: a análise prospectiva mostrou uma duração média dos cateteres de 290 dias. Não se observou nenhuma complicação em 340 pacientes. Entre as complicações precoces observamos 11 hematomas de trajeto, 10 arritmias, 6 tromboflebites de coto distal de veia jugular externa e uma infecção de bolsa de subcutânea. Entre as complicações tardias, observamos 38 complicações infecciosas (0,3/1000 dias de uso de cateter), 10 obstruções (0,08/1000 dias de uso de cateter) e 13 tromboses venosas profundas (0,11/1000 dias de uso de cateter). Foram retirados 77 cateterers, 29 relacionados às complicações e 48 por final de tratamento. 172 pacientes foram a óbito com o cateter e 181 pacientes ainda o utilizavam para quimioterapia. Conclusão: as baixas taxas de complicação obtidas nesse estudo que implicaram em perda do cateter confirmam a segurança e conveniência do uso dos acessos totalmente implantáveis em pacientes em regime prolongado de quimioterapia.