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1.
ChemSusChem ; 17(10): e202400289, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38503687

RESUMO

Furfural is an industrially relevant biobased chemical platform. Unlike classical furan, or C-alkylated furans, which have been previously described in the current literature, the =C5H bond of furfural is unreactive. As a result, on a large scale, C=C and C=O bond hydrogenation/hydrogenolysis is mainly performed, with furfuryl alcohol and methyl tetrahydrofuran being the two main downstream chemicals. Here, we show that the derivatization of the -CHO group of furfural restores the reactivity of its =C5H bond, thus permitting its double condensation on various alkyl aldehydes. Overcoming the recalcitrance of the =C5H bond of furfural has opened an access to a biobased monomer, whose potential have been investigated in the fabrication of renewably-sourced poly(silylether). By means of a combined theoretical-experimental study, a reactivity scale for furfural and its protected derivatives against carbonylated compounds has been established using an electrophilicity descriptor, a means to predict the molecular diversity and complexity this pathway may support, and also to de-risk any project related to this topic. Finally, by using performance criteria for industrial operations in the field of fuels and commodities, we discussed the industrial potential of this work in terms of cost, E-factor, reactor productivity and catalyst consumption.

2.
Angew Chem Int Ed Engl ; 63(12): e202319414, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38295149

RESUMO

Efficient plastic recycling processes are crucial for the production of value-added products or intermediates. Here, we present a multicatalytic route that allows the degradation of nitrile-butadiene rubber, cross-metathesis of the formed oligomers, and polymerization of the resulting dicarboxylic acids with bio-based diols, providing direct access to unsaturated polyesters. This one-pot approach combines the use of commercially available catalysts that are active and selective under mild conditions to synthesize renewable copolymers without the need to isolate intermediates.

3.
Surg Endosc ; 38(3): 1484-1490, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38233627

RESUMO

BACKGROUND: Laparoscopic subtotal cholecystectomy (LSC) is a recognised alternative to laparoscopic cholecystectomy (LC) when it is unsafe to achieve the "critical view of safety". Although LSC reduces the risk of bile duct injury, it is associated with increased morbidity, primarily due to bile leak. LSC can be classified as fenestrating (F-LSC) or reconstituting (R-LSC), with the latter being more complex. The objective of this study was to evaluate the two LSC techniques, their complications, and overall outcomes. METHODS: We conducted a retrospective analysis of all adult patients who underwent LSC between January 2015 and December 2021 using our electronic database. Data collected included patient demographics, prior acute biliary presentations, operative details/techniques, length of stay (LOS), 30-day complications, 30-day mortality, readmissions, and follow-up investigations/procedures. Descriptive statistics, Chi-squared tests, and relative risk were employed for data analysis. RESULTS: In the study period, LSC was performed on 170 patients, showing an increasing trend over time. Most procedures (76%) were performed in the acute setting, and 37.1% of patients had a history of previous acute biliary presentations. Fenestrating LSC was the most performed technique (115 [67.6%] vs. 55 [32.4%]). Complications occurred in 80 (47.1%) patients; 60 patients (35.3%) had a bile leak. 16 patients (9.4%) required reoperation, and readmission was observed in 14 patients (8.2%). F-LSC was associated with more complications [p = 0.03 RR 2.46 (95% CI 1.5-4)], more bile leaks [p < 0.01, RR 2.1 (95% CI 1.2-3.7)], greater need for rescue postoperative endoscopic retrograde cholangiopancreatography (ERCP) [p < 0.01, RR 3.8 (95% CI 1.4-10.2)], and longer LOS (6 vs. 4 days p < 0.01). CONCLUSION: Although LSC is seen as a safe alternative to open conversion, our findings demonstrate a high morbidity, including reoperation/reintervention, readmissions, and complications, associated with LSC especially with F-LSC. We suggest that if LSC is performed, the reconstituted technique should be chosen, if feasible.


Assuntos
Doenças Biliares , Colecistectomia Laparoscópica , Adulto , Humanos , Colecistectomia Laparoscópica/métodos , Estudos Retrospectivos , Colangiopancreatografia Retrógrada Endoscópica , Tempo de Internação
4.
Gut Pathog ; 16(1): 4, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38243246

RESUMO

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis in adults. Various C. difficile strains circulate currently, associated with different outcomes and antibiotic resistance profiles. However, most studies still focus on the reference strain 630 that does not circulate anymore, partly due to the lack of immunological tools to study current clinically important C. difficile PCR ribotypes. The goal of this study was to generate monoclonal antibodies recognizing various epidemic ribotypes of C. difficile. To do so, we immunized mice expressing human variable antibody genes with the Low Molecular Weight (LMW) subunit of the surface layer protein SlpA from various C. difficile strains. Monoclonal antibodies purified from hybridomas bound LMW with high-affinity and whole bacteria from current C. difficile ribotypes with different cross-specificities. This first collection of anti-C. difficile mAbs represent valuable tools for basic and clinical research.

5.
Cureus ; 15(8): e43473, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37711944

RESUMO

Introduction Biliary diseases are a major acute general surgical burden. Laparoscopic cholecystectomy is the gold standard surgical procedure, although it was discontinued during an outbreak. Effective management permits decisive therapy, symptom alleviation, and fewer hospitalizations and complications. Throughout the initial COVID-19 situation, surgical procedures for patients were delayed. Invasive services were required to employ conservative or non-operative therapy, which could lead to increased recurring presentations and biliary-pancreatic problems. Aim Examining the impact of COVID-19 on the outcomes and hospitalizations of patients suffering from gallstone, biliary tract, and pancreatic diseases.  Methods The retrospective analysis included patients with the following ICD-10 codes who presented to our unit: cholelithiasis (K80), cholecystitis (K81), and acute pancreatitis (K85). We compared the interval of the first COVID-19 pandemic wave, from March to August 2020, with the period before the pandemic, referred to as Pre-COVID-19. After applying exclusion criteria, a total of 868 patients were enrolled in the trial, having initially recruited around 1,400 individuals using these codes. Patients with inaccurate coding, cancer, or non-stone disease were excluded (e.g., alcoholic pancreatitis). The demographic information, admission details, investigations, surgical therapy, operating specifics, and postoperative complications of the patients were noted. Changes in surgical management, patient representation, and postoperative complications were the key outcomes. Results A statistically significant (p<0.05) rise was seen in repeat presentations in the COVID group, most likely due to the failure of definitive treatment. The other outcome is the distribution of presentations was comparable, patients with acute cholecystitis and gallstone pancreatitis showed statistically significant (p<0.05) lower rates of definitive therapy. Conclusion During the COVID period, all surgeries except those for cancer were halted. Unknown causes led to several consequences related to the gallbladder, biliary tract, and pancreas. Patients with cholecystitis, gallstone pancreatitis, and pancreatic inflammation experienced a lower probability of treatment. The increase in hospitalizations and self-presentations indicated that definitive therapy, designed to restrict COVID-19 exposure, actually increased patient risk. Despite this risk, we had no COVID-19 instances in our cohort. The evaluation of the long-term consequences of the pandemic on acute pancreatitis and its care will require a large-scale, multicenter investigation.

6.
Chemphyschem ; 24(15): e202300182, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37170881

RESUMO

We demonstrate that the strong N2 bond can be efficiently dissociated at low pressure and ambient temperature on a Si(111)-7x7 surface. The reaction was experimentally investigated by scanning tunnelling microscopy and X-ray photoemission spectroscopy. Experimental and density functional theory results suggest that relatively low thermal energy collision of N2 with the surface can facilitate electron transfer from the Si(111)-7x7 surface to the π*-antibonding orbitals of N2 that significantly weaken the N2 bond. This activated N2 triple bond dissociation on the surface leads to the formation of a Si3 N interface.

7.
Obes Surg ; 33(6): 1866-1875, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37067684

RESUMO

This study aims to be a contemporary review of mHealth apps in bariatric and metabolic surgery (BMS) to assess their quality using the Silberg scale as well as features, themes, usability, and medical/allied health professional involvement (MAPI). Apps were identified using search terms in the Android and Apple app stores. 52 apps were included. 42 (80.7%) apps main target users were patients. More than half, 27 (52%), targeted US based users. 29 (56%) had payment-restricted content. 42 (81%) had MAPI and the mean Silberg score was 5.2. Compared to previous studies the quality of BMS apps is improving with more MAPI and useful functionality. Wider use of mHealth apps for patient centred follow-up, management and care are yet to be widely implemented and explored.


Assuntos
Cirurgia Bariátrica , Aplicativos Móveis , Obesidade Mórbida , Telemedicina , Humanos , Smartphone , Obesidade Mórbida/cirurgia
8.
Chembiochem ; 24(8): e202300093, 2023 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-36942862

RESUMO

This symposium is the third PSL (Paris Sciences & Lettres) Chemical Biology meeting (2016, 2019, 2023) held at Institut Curie. This initiative originally started at Institut de Chimie des Substances Naturelles (ICSN) in Gif-sur-Yvette (2013, 2014), under the directorship of Professor Max Malacria, with a strong focus on chemistry. It was then continued at the Institut Curie (2015) covering a larger scope, before becoming the official PSL Chemical Biology meeting. This latest edition was postponed twice for the reasons that we know. This has given us the opportunity to invite additional speakers of great standing. This year, Institut Curie hosted around 300 participants, including 220 on site and over 80 online. The pandemic has had, at least, the virtue of promoting online meetings, which we came to realize is not perfect but has its own merits. In particular, it enables those with restricted time and resources to take part in events and meetings, which can now accommodate unlimited participants. We apologize to all those who could not attend in person this time due to space limitation at Institut Curie.


Assuntos
Biologia , Humanos , Paris
9.
Chem Sci ; 14(2): 362-371, 2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36687351

RESUMO

The in vitro to in vivo translation of metal-based cytotoxic drugs has proven to be a significant hurdle in their establishment as effective anti-cancer alternatives. Various nano-delivery systems, such as polymeric nanoparticles, have been explored to address the pharmacokinetic limitations associated with the use of these complexes. However, these systems often suffer from poor stability or involve complex synthetic procedures. To circumvent these problems, we report here a simple, one-pot procedure for the preparation of covalently-attached Ru-polylactide nanoparticles. This methodology relies on the ring-opening polymerization of lactide initiated by a calcium alkoxide derivative formed from calcium bis(trimethylsilyl amide) and a hydroxyl-bearing ruthenium complex. This procedure proceeds with high efficiency (near-quantitative incorporation of Ru in the polymer) and enables the preparation of polymers with varying molecular weights (2000-11000 Da) and high drug loadings (up to 68% w/w). These polymers were formulated as narrowly dispersed nanoparticles (110 nm) that exhibited a slow and predictable release of the ruthenium payload. Unlike standard encapsulation methods routinely used, the release kinetics of these nanoparticles is controlled and may be adjusted on demand, by tuning the size of the polymer chain. In terms of cytotoxicity, the nanoparticles were assessed in the ovarian cancer cell line A2780 and displayed potency comparable to cisplatin and the free drug, in the low micromolar range. Interestingly, the activity was maintained when tested in a cisplatin-resistant cell line, suggesting a possible orthogonal mechanism of action. Additionally, the internalization in tumour cells was found to be significantly higher than the free ruthenium complex (>200 times in some cases), clearly showcasing the added benefit in the drug's cellular permeation and accumulation of the drug. Finally, the in vivo performance was evaluated for the first time in mice. The experiments showed that the intravenously injected nanoparticles were well tolerated and were able to significantly improve the pharmacokinetics and biodistribution of the parent drug. Not only was the nanosystem able to promote an 18-fold increase in tumour accumulation, but it also allowed a considerable reduction of drug accumulation in vital organs, achieving, for example, reduction levels of 90% and 97% in the brain and lungs respectively. In summary, this simple and efficient one-pot procedure enables the generation of stable and predictable nanoparticles capable of improving the cellular penetration and systemic accumulation of the Ru drug in the tumour. Altogether, these results showcase the potential of covalently-loaded ruthenium polylactide nanoparticles and pave the way for its exploitation and application as a viable tool in the treatment of ovarian cancer.

10.
Molecules ; 27(13)2022 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-35807313

RESUMO

The most versatile furanic building block for chemical and polymer applications is 2,5-furandicarboxylic acid. However, the classical 2,5-furandicarboxylic acid production methodology has been found to have significant drawbacks that hinder industrial-scale production. This review highlights new alternative methods to synthesize 2,5-furandicarboxylic acid that are both more advantageous and attractive than conventional oxidation of 5-hydroxymethylfurfural. This review also focuses on the use of 2,5-furandicarboxylic acid as a polymer precursor and the various potential applications that arise from these furan-based materials.


Assuntos
Ácidos Dicarboxílicos , Polímeros , Furanos , Oxirredução
11.
Acc Chem Res ; 55(16): 2168-2179, 2022 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-35881825

RESUMO

Almost all aspects of daily life involve polymers in some form or the other. However, polymer production is largely based on finite feedstocks. These limitations combined with environmental concerns force us to rethink the strategies for the synthesis of these materials. As an abundant and renewable resource, biomass is composed of a very diverse range of molecules that deserve to be valorized. The development of new methods for transforming biomass into resources suitable for polymer production remains a crucial hurdle on the road to a more sustainable chemical economy. The main challenge is to design efficient and selective transformations of abundant and inexpensive raw materials into innovative polymers. For the chemical industry to meet these challenges, process intensification must play an important role in developing cleaner and more energy-efficient technologies while aiming for safer and more sustainable processes. Catalysis is an important tool to support more sustainable plastics production by being ideally efficient, practical, and versatile. In this regard, the creation of sustainable polymers through one-pot catalysis represents an exciting frontier in materials science.In this Account, we describe some of the published advances for achieving one-pot synthesis of biobased monomers and the resulting (co)polymers. These studies demonstrate that one-pot reactions can produce sustainable materials for a wide range of applications. We show that these new multistep "one-pot" approaches are very promising from an academic and industrial point of view. These synthetic schemes have indeed allowed us to investigate the formation of new polyesters, polypeptides, and poly(meth)acrylates by different polymerization mechanisms. We discuss their efficiency by highlighting their ability to perform multiple (quantitative) synthetic transformations and bond formation steps while bypassing multiple purification procedures at the same time. While enabling the development of novel polymeric structures, we demonstrate that these one-pot procedures can also contribute to reducing the environmental footprint.In light of the growing concerns for sustainable development, these procedures may therefore allow, in the near future, one to prepare sustainable polymeric materials with advanced properties through extremely simplified routes from renewable feedstocks. Among these materials, block and alternating copolymers are unique structures that can exhibit a wide range of properties. While their multistep synthesis remains a demanding process, the one-pot synthesis of these polymers is much more scalable and can create multiblock or alternating copolymers with a wide range of potential sequences. These approaches then give access to materials whose structure and functionality can be designed to suit the need.


Assuntos
Poliésteres , Polímeros , Biomassa , Catálise , Polimerização , Polímeros/química
12.
Angew Chem Int Ed Engl ; 61(7): e202113443, 2022 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-34902211

RESUMO

The design of new materials with tunable properties and intrinsic recyclability, derived from biomass under mild conditions, stands as a gold standard in polymer chemistry. Reported herein are platinum complexes which catalyze the formation of poly(silylether)s (PSEs) at low catalyst loadings. These polymers are directly obtained from dual-functional biobased building blocks such as 5-hydroxymethylfurfural (HMF) or vanillin, coupled with various dihydrosilanes. Access to different types of copolymer architectures (statistical or alternating) is highlighted by several synthetic strategies. The materials obtained were then characterized as low Tg materials (ranging from -60 to 29 °C), stable upon heating (T-5% up to 301 °C) and resistant towards uncatalyzed methanolysis. Additionally, quantitative chemical recycling of several PSEs could be triggered by acid-catalyzed hydrolysis or methanolysis. These results emphasize the interest of biobased poly(silylether)s as sustainable materials with high recycling potential.

13.
BMJ Open ; 12(12): e059463, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36600359

RESUMO

INTRODUCTION: Incisional hernia has an incidence of up to 20% following laparotomy and is associated with significant morbidity and impairment of quality of life. A variety of surgical strategies including techniques and mesh types are available to manage patients with incisional hernia. Previous works have reported significant heterogeneity in outcome reporting for abdominal wall herniae, including ventral and inguinal hernia. This is coupled with under-reporting of important clinical and patient-reported outcomes. The lack of standardisation in outcome reporting contributes to reporting bias, hinders evidence synthesis and adequate data comparison between studies. This project aims to develop a core outcome set (COS) of clinically important, patient-oriented outcomes to be used to guide reporting of future research in incisional hernia. METHODS: This project has been designed as an international, multicentre, mixed-methods project. Phase I will be a systematic review of current literature to examine the current clinical and patient-reported outcomes for incisional hernia and abdominal wall reconstruction. Phase II will identify the outcomes of importance to all key stakeholders through in depth qualitative interviews. Phase III will achieve consensus on outcomes of most importance and for inclusion into a COS through a Delphi process. Phase IV will achieve consensus on the outcomes that should be included in a final COS. ETHICS AND DISSEMINATION: The adoption of this COS into clinical and academic practice will be endorsed by the American, British and European Hernia Societies. Its utilisation in future clinical research will enable appropriate data synthesis and comparison and will enable better clinical interpretation and application of the current evidence base. This study has been registered with the Core Outcome Measures in Effectiveness Trials initiative. PROSPERO REGISTRATION NUMBER: CRD42018090084.


Assuntos
Hérnia Ventral , Hérnia Incisional , Humanos , Hérnia Incisional/epidemiologia , Hérnia Incisional/cirurgia , Qualidade de Vida , Avaliação de Resultados em Cuidados de Saúde/métodos , Hérnia Ventral/cirurgia , Projetos de Pesquisa , Técnica Delphi , Resultado do Tratamento , Revisões Sistemáticas como Assunto
14.
Chem Soc Rev ; 50(24): 13587-13608, 2021 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-34786575

RESUMO

This review highlights recent developments in the field of biodegradable polymeric materials intended to replace non-degradable conventional plastics, focusing on studies from the last ten years involving the stereoselective ring-opening polymerization of cyclic esters. This encompasses exciting advances in both catalyst design and monomer scope. Notably, the last decade has seen the emergence of metal-free stereocontrolled ROP for instance, as well as the synthesis and stereocontrolled polymerization of new types of chiral monomers. This study will emphasize recent stereoselective polymerization catalysts and chiral monomers and will focus on stereocontrol quantification, the mechanisms of stereocontrol and their differentiation if reported and studied for a specific catalyst system.


Assuntos
Poliésteres , Polímeros , Catálise , Ésteres , Polimerização
15.
J Am Chem Soc ; 143(33): 13401-13407, 2021 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-34379408

RESUMO

A [Ni/Mg]-catalyzed orthogonal tandem polymerization has been developed starting from enol phosphates. Initial investigations conducted on branched 1,3-dienes as monomers enabled identification of a Mg-initiated polymerization process leading to 1,4-cis-polydienes. When aryl enol phosphates are used as monomers, the [Ni/Mg]-catalyzed tandem polymerization affords 1,4-cis-polydienes with selectivities up to 99%. Elastomeric or crystalline materials were obtained by simple structural modifications of the monomeric unit. This tandem approach appears as a straightforward and efficient way to enforce diversity and selectivity in diene polymerization while retaining a fair degree of control, just as observed for stepwise systems that are accessible through established time- and manpower-consuming synthetic procedures.

16.
Angew Chem Int Ed Engl ; 60(35): 19374-19382, 2021 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-34152679

RESUMO

Shifting from petrochemical feedstocks to renewable resources can address some of the environmental issues associated with petrochemical extraction and make plastics production sustainable. Therefore, there is a growing interest in selective methods for transforming abundant renewable feedstocks into monomers suitable for polymer production. Reported herein are one-pot catalytic systems, that are active, productive, and selective under mild conditions for the synthesis of copolymers from renewable materials. Each system allows for anhydride formation, alcohol acylation and/or acid esterification, as well as polymerization of the formed (meth)acrylates, providing direct access to a new library of unique poly(meth)acrylates.

17.
Macromol Rapid Commun ; 42(3): e2000530, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33433958

RESUMO

To prepare biobased polymers, particular attention must be paid to the obtention of the monomers from which they are derived. (Meth)acrylates and their analogs constitute such a class of monomers that have been extensively studied due to the wide range of polymers accessible from them. This review therefore aims to highlight the progresses made in the production and polymerization of (meth)acrylates and their analogs. Acrylic acid production from biomass is close to commercialization, as three different high-potential intermediates are identified: glycerol, lactic acid, and 3-hydroxypropionic acid. Biobased methacrylic acid is less common, but several promising options are available, such as the decarboxylation of itaconic acid or the dehydration of 2-hydroxyisobutyric acid. Itaconic acid is also a vinylic monomer of great interest, and polymers derived from it have already found commercial applications. Methylene butyrolactones are promising monomers, obtained from bioresources via three different intermediates: levulinic, succinic, or itaconic acid. Although expensive, methylene butyrolactones have a strong potential for the production of high-performance polymers. Finally, ß-substituted acrylic monomers, such as cinnamic, fumaric, muconic, or crotonic acid, are also examined, as they provide an original access to biobased materials from various renewable raw materials, such as protein waste, lignin, or wastewater.


Assuntos
Acrilatos , Polímeros , Lignina , Polimerização
18.
Colorectal Dis ; 23(1): 284-297, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33002261

RESUMO

AIM: Emergency colorectal surgery is associated with significant morbidity and mortality. Most general surgeons have a subspecialty, which forms the focus of their elective work, allowing development of specialist skill sets. The aim of this study was to assess the impact of consultant subspecialization on patient outcomes following emergency colorectal resections. METHODS: Data were requested for all emergency admissions under a general surgeon between 1 January 2002 and 31 December 2016 within the north of England. These were acquired from individual Trusts following Caldicott approval. Data included demographics, diagnoses and any procedures undertaken. Patients were assigned to cohorts based on the subspecialist interest of the consultant they were under the care of. The primary outcome of interest was 30-day postoperative mortality. Categorical data were compared with the chi-squared test, and continuous data with the t test or ANOVA. A logistic regression model determined factors associated with 30-day in-hospital mortality. RESULTS: Overall, 7648 emergency colorectal resections were performed with a 30-day postoperative mortality of 13.8%. This was significantly lower if the responsible consultant was a colorectal surgeon compared with other general surgery subspecialties (11.8% vs. 15.2%, P < 0.001). This was significant on univariate analysis (OR 0.75, P < 0.001); however, following multivariable adjustment, this was not statistically significant (P = 0.380). The colorectal specialists had a higher laparoscopy rate than their colleagues-9.8% versus 6.8% (P < 0.001). Stoma rates were also lower (46.9% vs. 51.0%, P = 0.001) and anastomosis rates higher (55.9% vs. 49.3%, P < 0.001) amongst colorectal surgeons. CONCLUSION: These findings add to the growing body of evidence that patient outcomes may be improved by involving subspecialists in colorectal emergencies.


Assuntos
Neoplasias Colorretais , Cirurgia Colorretal , Neoplasias Colorretais/cirurgia , Emergências , Inglaterra , Humanos , Estudos Retrospectivos
19.
Nanoscale ; 13(1): 349-354, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33346311

RESUMO

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic components, catalysts, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by electrons between the tip of a scanning tunnelling microscope and the Si(111)√3 ×√3 R30°-B surface. This electron transfer event only occurs when the bias voltage is below -4.5 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively 'switch on' a sequence leading to the formation of oligomers of defined size distribution thanks to the on-surface confinement of the reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

20.
Pharmaceutics ; 12(10)2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33066200

RESUMO

Antimicrobial photodynamic therapy (aPDT) also known as photodynamic inactivation (PDI) is a promising strategy to eradicate pathogenic microorganisms such as Gram-positive and Gram-negative bacteria. This therapy relies on the use of a molecule called photosensitizer capable of generating, from molecular oxygen, reactive oxygen species including singlet oxygen under light irradiation to induce bacteria inactivation. Ru(II) polypyridyl complexes can be considered as potential photosensitizers for aPDT/PDI. However, to allow efficient treatment, they must be able to penetrate bacteria. This can be promoted by using nanoparticles. In this work, ruthenium-polylactide (RuPLA) nanoconjugates with different tacticities and molecular weights were prepared from a Ru(II) polypyridyl complex, RuOH. Narrowly-dispersed nanoparticles with high ruthenium loadings (up to 53%) and an intensity-average diameter < 300 nm were obtained by nanoprecipitation, as characterized by dynamic light scattering (DLS). Their phototoxicity effect was evaluated on four bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa) and compared to the parent compound RuOH. RuOH and the nanoparticles were found to be non-active towards Gram-negative bacterial strains. However, depending on the tacticity and molecular weight of the RuPLA nanoconjugates, differences in photobactericidal activity on Gram-positive bacterial strains have been evidenced whereas RuOH remained non active.

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