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1.
J Hazard Mater ; 421: 126824, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34396973

RESUMO

Hydrophobic and oleophilic materials are attractive candidates for efficient oil collection due to their excellent oil-water separation. However, the most of currently reported oil adsorption materials are limited resources or require complicated preparation steps, which causes high energy consumption and not be practical for large-scale application. Herein, we report a facile strategy to modify the wettability of Enteromorpha from hydrophilic to hydrophobic, which not only greatly reduces energy consumption but also shows the outstanding capacity for oil-water separation with the maximum adsorption capacities is 11.4 g/g and the contact angle reaches 137°. The successful modification of the Enteromorpha is achieved by grafting n-octyltriethoxysilane on the surface of the pristine Enteromorpha. The hydrophobic and superoleophilic Enteromorpha guarantee adequate voids in the fibrous bundles only for oil adsorption and the oil floating on the seawater is removed by the formation of hydrogen bonding between oil and modified Enteromorpha. By optimizing test, the optimal adsorption conditions are adsorption time of 60 min, oil-water ratio of 1:10 and pH of 7. Our reported hydrophobic organosilane modified Enteromorpha will open a new avenue to control marine oil pollution and suppress the damage of Enteromorpha to the marine ecology system.


Assuntos
Compostos de Organossilício , Poluição por Petróleo , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Poluição por Petróleo/análise , Água
2.
Chemosphere ; 287(Pt 3): 132342, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34583298

RESUMO

Organosilane, with functional organic groups attached to inorganic silicon atoms, exhibits excellent passivation performance for pyrite. However, a considerable number of micro-cracks will gradually appear on the surface of passivation film under long-term corrosion of oxidizing medium, resulting in a significant decrease of passivation effect. To improve the stability and long-term performance of organosilane coating, a novel passivator (PT-ATP@HQ) with self-healing function was prepared to inhibit the oxidation of pyrite. We chose 3-mercaptopropyltrimethoxysilane (Prop-SH) and tetraethoxysilane (TEOS) as the host coating (PT), and attapulgite clay (ATP) loaded with 8-hydroxyquinoline (8-HQ) was used to endow the coating with better passivation and self-healing performance. The electrochemical and chemical leaching results showed that the addition of ATP@HQ greatly improved the passivation performance of PT coating. The passivation efficiencies of total Fe and SO42- reached to 88.1% and 79.2%, respectively. We also found that the protective capability of the scratched PT-ATP@HQ coating can be recovered automatically through 8-HQ release from ATP. The passivation and self-healing mechanisms were investigated by FT-IR, XPS, 29Si NMR, and other characterization methods, which were as follows: firstly, the organosilanes hydrolyzed to form highly active silanol groups, then dehydration condensation reaction occurred between silanol molecules and ATP@HQ to obtain cross-linked network structure connected by Si-O-Si bonds. After that, Si-OH groups reacted with the hydroxyl groups of pyrite to form Fe-O-Si bonds, thereby an inert and dense passivation film attached to the surface of pyrite. Once the passivation film is locally damaged, 8-HQ will automatically release to repair the cracks.


Assuntos
Compostos de Organossilício , Argila , Ferro , Compostos de Magnésio , Oxirredução , Compostos de Silício , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfetos
3.
PLoS One ; 16(10): e0259216, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34705881

RESUMO

We proposed an experimental methodology for producing films on substrates with an ion beam induced chemical vapor deposition (IBICVD) method using hexamethyldisilazane (HMDS) as a source material. In this study, both HMDS and ion beam were simultaneously injected onto a Si substrate. We selected Ar+ and N+ as the ion beam. The energy of the ion beam was 101 eV. Temperature of the Si substrate was set at 540 °C. After the experiments, films were found to be deposited on the substrates. The films were then analyzed by Fourier transform infrared (FTIR) spectroscopy, stylus profilometer, X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS results showed that silicon carbide films containing small amount of nitrogen were formed when Ar+ ions were injected in conjunction with HMDS. On the other hand, in the cases of N+ ion beam irradiation, silicon nitride films involving small amount of carbon were formed. It was noted that no film deposition was observed when HMDS alone was supplied to the substrates without any ion beam injections.


Assuntos
Compostos Inorgânicos de Carbono/química , Nanoestruturas/química , Nitrogênio/química , Compostos de Organossilício/química , Compostos de Silício/química , Argônio/química , Volatilização
4.
Cancer Control ; 28: 10732748211045275, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34623943

RESUMO

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has overwhelmed the capacity of healthcare systems worldwide. Cancer patients, in particular, are vulnerable and oncology departments drastically needed to modify their care systems and established new priorities. We evaluated the impact of SARS-CoV-2 on the activity of a single cancer center. METHODS: We performed a retrospective analysis of (i) volumes of oncological activities (2020 vs 2019), (ii) patients' perception rate of the preventive measures, (iii) patients' SARS-CoV-2 infections, clinical signs thereof, and (iv) new diagnoses made during the SARS-CoV-2 pandemic. RESULTS: As compared with a similar time frame in 2019, the overall activity in total numbers of outpatient chemotherapy administrations and specialist visits was not statistically different (P = .961 and P = .252), while inpatient admissions decreased for both medical oncology and thoracic oncology (18% (P = .0018) and 44% (P < .0001), respectively). Cancer diagnosis plummeted (-34%), but no stage shift could be demonstrated.Acceptance and adoption of hygienic measures was high, as measured by a targeted questionnaire (>85%). However, only 46.2% of responding patients regarded telemedicine, although widely deployed, as an efficient surrogate to a consultation.Thirty-three patients developed SARS-CoV-2, 27 were hospitalized, and 11 died within this time frame. These infected patients were younger, current smokers, and suffered more comorbidities. CONCLUSIONS: This retrospective cohort analysis adds to the evidence that continuation of active cancer therapy and specialist visits is feasible and safe with the implementation of telemedicine. These data further confirm the impact of SARS-CoV-2 on cancer care management, cancer diagnosis, and impact of infection on cancer patients.


Assuntos
COVID-19/epidemiologia , Institutos de Câncer/organização & administração , Institutos de Câncer/estatística & dados numéricos , Neoplasias/epidemiologia , Neoplasias/terapia , Fatores Etários , Comorbidade , Ciclopentanos , Humanos , Controle de Infecções/organização & administração , Neoplasias/diagnóstico , Neoplasias/mortalidade , Compostos de Organossilício , Pandemias , Percepção , Estudos Retrospectivos , SARS-CoV-2
5.
Phys Rev Lett ; 127(10): 108001, 2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34533362

RESUMO

Limited-valency colloidal particles can self-assemble into polymeric structures analogous to molecules. While their structural equilibrium properties have attracted wide attention, insight into their dynamics has proven challenging. Here, we investigate the polymerization dynamics of semiflexible polymers in 2D by direct observation of assembling divalent particles, bonded by critical Casimir forces. The reversible critical Casimir force creates living polymerization conditions with tunable chain dissociation, association, and bending rigidity. We find that unlike dilute polymers that show exponential size distributions in excellent agreement with Flory theory, concentrated samples exhibit arrest of rotational and translational diffusion due to a continuous isotropic-to-nematic transition in 2D, slowing down the growth kinetics. These effects are circumvented by the addition of higher-valency particles, cross linking the polymers into networks. Our results connecting polymer flexibility, polymer interactions, and the peculiar isotropic-nematic transition in 2D offer insight into the polymerization processes of synthetic two-dimensional polymers and biopolymers at membranes and interfaces.


Assuntos
Coloides/química , Modelos Químicos , Cinética , Metacrilatos/química , Compostos de Organossilício/química , Polimerização , Poliestirenos/química
6.
J Org Chem ; 86(18): 13160-13168, 2021 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-34478290

RESUMO

An efficient route for the synthesis of 1-aryl-2,2-difluoroalkenes via 1,2-desilylative defluorination is disclosed. Only a catalytic amount of fluoride source is required to initiate the desilylation and afford gem-difluoroalkenes in very good to quantitative yields, using mild reaction conditions in dimethyl carbonate as a green solvent. This reaction uses (1-aryl)-2,2,2-trifluoroethyl-silanes, which are easily prepared via the insertion reaction of trifluoroethyl diazo alkanes into the Si-H bond of tertiary organosilanes. (1-Aryl)-perfluoroalkyl-silanes cleanly afford the corresponding (Z)-1-benzylideneperfluoroalkanes, which upon hydrodefluorination furnish the (E)-ß(perfluoroalkyl)styrene derivatives with excellent yield and complete stereoselectivity. A one-pot system involving sequential insertion and desilylative-defluorination is also suitable for this transformation. This method demonstrates the usefulness of organosilanes toward the preparation of fluorinated alkenes as synthetically useful targets.


Assuntos
Compostos de Organossilício , Silanos , Alcenos , Catálise , Fluoretos
7.
J Phys Chem Lett ; 12(39): 9657-9661, 2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34586816

RESUMO

Silaffin peptide R5 is key for the biogenesis of silica cell walls of diatoms. Biosilification by the R5 peptide has potential in biotechnology, drug development, and materials science due to its ability to precipitate stable, high fidelity silica sheets and particles. A true barrier for the design of novel peptide-based architectures for wider applications has been the limited understanding of the interfacial structure of R5 when precipitating silica nanoparticles. While R5-silica interactions have been studied in detail at flat surfaces, the structure within nanophase particles is still being debated. We herein elucidate the conformation of R5 in its active form within silica particles by combining interface-specific vibrational spectroscopy data with solid-state NMR torsion angles using theoretical spectra. Our calculations show that R5 is structured and undergoes a conformational transition from a strand-type motif in solution to a more curved, contracted structure when interacting with silica precursors.


Assuntos
Diatomáceas/metabolismo , Espectroscopia de Ressonância Magnética , Fragmentos de Peptídeos/química , Precursores de Proteínas/química , Dióxido de Silício/química , Sequência de Aminoácidos , Nanopartículas/química , Compostos de Organossilício/química
8.
Int J Mol Sci ; 22(16)2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34445073

RESUMO

Human immunodeficiency virus (HIV-1) is still a major problem, not only in developing countries but is also re-emerging in several developed countries, thus the development of new compounds able to inhibit the virus, either for prophylaxis or treatment, is still needed. Nanotechnology has provided the science community with several new tools for biomedical applications. G2-S16 is a polyanionic carbosilane dendrimer capable of inhibiting HIV-1 in vitro and in vivo by interacting directly with viral particles. One of the main barriers for HIV-1 eradication is the reservoirs created in primoinfection. These reservoirs, mainly in T cells, are untargetable by actual drugs or immune system. Thus, one approach is inhibiting HIV-1 from reaching these reservoir cells. In this context, macrophages play a main role as they can deliver viral particles to T cells establishing reservoirs. We showed that G2-S16 dendrimer is capable of inhibiting the infection from infected macrophages to healthy T CD4/CD8 lymphocytes by eliminating HIV-1 infectivity inside macrophages, so they are not able to carry infectious particles to other body locations, thus preventing the reservoirs from forming.


Assuntos
Alcanossulfonatos/farmacologia , Fármacos Anti-HIV/farmacologia , Dendrímeros/farmacologia , Infecções por HIV/tratamento farmacológico , HIV-1/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Compostos de Organossilício/farmacologia , Silanos/farmacologia , Linhagem Celular , Células Cultivadas , Infecções por HIV/transmissão , Humanos , Macrófagos/virologia , Polieletrólitos/farmacologia
9.
J Chromatogr A ; 1653: 462418, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34340056

RESUMO

The present work systematically investigates a new strategy for the functionalization of silica gel using alkyl silatrane chemistry instead of alkylsilanes for synthesis of chromatographic stationary phases. In this work, silica was chemically modified for further functionalization by a thiol-ene click reaction. Thus, 3-mercaptopropylsilatrane (MPS) was used which is capable to form self-assembled monolayers (SAM) on top of silanol surfaces in a controlled manner as previously shown for silicon wafers. The utility of this chemistry for stationary phase synthesis in liquid chromatography was not evaluated yet. Hence, silica surface modifications using MPS were studied in comparison to established 3-mercaptopropyltrimethoxysilane (MPTMS) chemistry. First, the employed elemental analysis method was validated and it showed excellent intra-day and inter-day precisions (typically less than 5% RSD). It could be shown that the reaction kinetics of MPS was roughly 35-times faster than with MPTMS. After 30 min reaction time with MPS, the thiol content reached 74% of the maximal coverage. Due to controlled chemistry with MPS, which does not lead to oligomeric siloxane network at the silica surface, the ligand coverage was lower. However, multiple silanization cycles with MPS led to a dense surface coverage (around 4 µmol m-2). 29Si cross polarization/magic angle spinning (CP/MAS) solid-state NMR revealed distinct T1/T2/T3 ratios for MPS and MPTMS materials with up to 80% T3 (indicative for trifunctional siloxane linkage) for MPS and around 20% T3 for MPTMS. This indicates a more homogeneous, thinner monolayer film of MPS on the silica surface, as compared to an irregular thick oligomeric siloxane network with MPTMS. Bonding of quinine carbamate as chiral selector afforded an efficient chiral stationary phase (CSP) for chromatographic enantiomer separation. Separation factors were comparable to MPTMS-bonded CSP, however, chromatographic efficiency was much better for the MPS-bonded CSP. H/u curves indicated a reduced mass transfer resistance by roughly factor 3 for MPS- compared to MPTMS-bonded CSP. This confirms better chromatographic performance of surfaces with homogeneous monolayer compared to network structures on the silica surface which suffer from poor stationary phase mass transfer.


Assuntos
Cromatografia Líquida , Compostos de Organossilício , Dióxido de Silício , Compostos de Sulfidrila , Compostos Bicíclicos Heterocíclicos com Pontes , Química Analítica , Cromatografia Líquida/métodos , Siloxanas
10.
Colloids Surf B Biointerfaces ; 207: 112010, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34392081

RESUMO

Rapid and efficient pesticide detection methods are particularly important due to the growing problems of pesticide residues. Here, a new azo-based porous organic polymer, Azo(Fe)PPOP, was prepared from octa(amino-phenyl)silsesquioxane (OAPS) and iron(III) 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (FeTPP(NO2)4) via a simple coupling reaction without the participation of metal catalysts. The inorganic cage units of OAPS endowed Azo(Fe)PPOP a porous framework, high surface area, favorably thermal and chemical stability. In Azo(Fe)PPOP, iron(III) porphyrin units were individually isolated in a fixed location, which could effectively avoid dimerization or self-oxidation as happens as in the case of porphyrin monomers. Such a unique structure made Azo(Fe)PPOP exhibit an excellent peroxidase-like catalytic performance in the presence of H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). Because of these advantages, we established a selective, facile, and sensitive colorimetric platform for direct detection of malathion within a very short time (3 min) with a low detection limit (8.5 nM). In addition, the recognition mechanism between Azo(Fe)PPOP and malathion was verified using X-ray photoelectron spectroscopy spectra. The practicality of the constructed platform was further executed by the detection of the pesticide in soil and food samples.


Assuntos
Compostos de Anilina/química , Colorimetria , Malation/análise , Metaloporfirinas , Compostos de Organossilício/química , Peroxidase/química , Compostos Férricos , Peróxido de Hidrogênio , Polímeros , Porosidade
11.
Molecules ; 26(13)2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34279386

RESUMO

The selective inhibition of immunoproteasome is a valuable strategy to treat autoimmune, inflammatory diseases, and hematologic malignancies. Recently, a new series of amide derivatives as non-covalent inhibitors of the ß1i subunit with Ki values in the low/submicromolar ranges have been identified. Here, we investigated the binding mechanism of the most potent and selective inhibitor, N-benzyl-2-(2-oxopyridin-1(2H)-yl)propanamide (1), to elucidate the steps from the ligand entrance into the binding pocket to the ligand-induced conformational changes. We carried out a total of 400 ns of MD-binding analyses, followed by 200 ns of plain MD. The trajectories clustering allowed identifying three representative poses evidencing new key interactions with Phe31 and Lys33 together in a flipped orientation of a representative pose. Further, Binding Pose MetaDynamics (BPMD) studies were performed to evaluate the binding stability, comparing 1 with four other inhibitors of the ß1i subunit: N-benzyl-2-(2-oxopyridin-1(2H)-yl)acetamide (2), N-cyclohexyl-3-(2-oxopyridin-1(2H)-yl)propenamide (3), N-butyl-3-(2-oxopyridin-1(2H)-yl)propanamide (4), and (S)-2-(2-oxopyridin-1(2H)-yl)-N,4-diphenylbutanamide (5). The obtained results in terms of free binding energy were consistent with the experimental values of inhibition, confirming 1 as a lead compound of this series. The adopted methods provided a full dynamic description of the binding events, and the information obtained could be exploited for the rational design of new and more active inhibitors.


Assuntos
Simulação de Acoplamento Molecular , Complexo de Endopeptidases do Proteassoma/química , Inibidores de Proteassoma/farmacologia , Sítios de Ligação , Dipeptídeos/química , Dipeptídeos/farmacologia , Simulação de Dinâmica Molecular , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Compostos de Organossilício/química , Compostos de Organossilício/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/química , Ligação Proteica
12.
J Phys Chem B ; 125(30): 8460-8471, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34296881

RESUMO

We report on charge-transfer dynamics of newly designed acceptor-donor-acceptor organosilanes, with a specific focus on how donor-acceptor combination and local chemical environment can be used to control the lifetime for intramolecular charge-separation between silane electron donors and organic acceptors. In this work linear oligosilanes were capped with arene-vinyl end groups of variable electron-accepting strength: weak (diester vinyl), intermediate (ester,cyano vinyl), and strong (dicyanovinyl). Ultrafast transient absorption spectroscopy was used to characterize their structure-dependent charge-transfer and recombination behaviors. All structures exhibit similar photoinduced ultrafast spectral dynamics that we ascribe to relaxation of the nascent charge-separated excited state followed by a return to the ground state via charge recombination. We find that relaxation of the nascent "hot" charge-separated excited state scales with the strength of dipole-dipole interactions between solvent molecules and the polar arene-vinyl acceptor. Furthermore, electron-accepting strength governs whether electronic coupling dictates charge recombination rate: weak acceptors produce charge-separated states that exhibit relatively large electronic coupling for back-electron transfer (approaching the adiabatic limit) that result in fast recombination, whereas the strong and moderate-strength acceptors support more stable charge-separated states with weaker coupling and longer lifetimes. We find that recombination rates increase substantially for structures with weak and moderate-strength acceptors in cyclohexane (i.e., negligible solvent reorganization energy), which we attribute to an increased electronic coupling in a nonpolar solvent environment where charge pairs are weakly screened. In contrast, for structures with strong electron acceptors, the very low reorganization energy of cyclohexane places back-electron transfer even further into the Marcus inverted regime, with a resultant increase in charge-separation lifetime. Together these results provide critical insights on how to tune photoinduced charge-transfer behavior in organic-inorganic hybrids that have potential material applications in molecular electronics and optoelectronics.


Assuntos
Compostos de Organossilício , Transporte de Elétrons , Elétrons , Recombinação Genética , Análise Espectral
13.
Cochrane Database Syst Rev ; 7: CD012997, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34219224

RESUMO

BACKGROUND: Haemolytic uraemic syndrome (HUS) is a common cause of acquired kidney failure in children and rarely in adults. The most important risk factor for development of HUS is a gastrointestinal infection by Shiga toxin-producing Escherichia coli (STEC). This review addressed the interventions aimed at secondary prevention of HUS in patients with diarrhoea who were infected with a bacteria that increase the risk of HUS. OBJECTIVES: Our objective was to evaluate evidence regarding secondary preventative strategies for HUS associated with STEC infections. In doing so, we sought to assess the effectiveness and safety of interventions as well as their potential to impact the morbidity and death associated with this condition. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Register of Studies up to 12 November 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. SELECTION CRITERIA: Studies were considered based on the methods, participants, and research goals. Only randomised controlled trials were considered eligible for inclusion. The participants of the studies were paediatric and adult patients with diarrhoeal illnesses due to STEC. The primary outcome of interest was incidence of HUS. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures as recommended by Cochrane. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: We identified four studies (536 participants) for inclusion that investigated four different interventions including antibiotics (trimethoprim-sulfamethoxazole), anti-Shiga toxin antibody-containing bovine colostrum, Shiga toxin binding agent (Synsorb Pk: a silicon dioxide-based agent), and a monoclonal antibody against Shiga toxin (urtoxazumab). The overall risk of bias was unclear for selection, performance and detection bias and low for attrition, reporting and other sources of bias. It was uncertain if trimethoprim-sulfamethoxazole reduced the incidence of HUS compared to no treatment (47 participants: RR 0.57, 95% CI 0.11-2.81, very low certainty evidence). Adverse events relative to this review, need for acute dialysis, neurological complication and death were not reported. There were no incidences of HUS in either the bovine colostrum group or the placebo group. It was uncertain if bovine colostrum caused more adverse events (27 participants: RR 0.92, 95% CI 0.42 to 2.03; very low certainty evidence). The need for acute dialysis, neurological complications or death were not reported. It is uncertain whether Synsorb Pk reduces the incidence of HUS compared to placebo (353 participants: RR 0.93, 95% CI 0.39 to 2.22; very low certainty evidence). Adverse events relevant to this review, need for acute dialysis, neurological complications or death were not reported. One study compared two doses of urtoxazumab (3.0 mg/kg and 1.0 mg/kg) to placebo. It is uncertain if either 3.0 mg/kg urtoxazumab (71 participants: RR 0.34, 95% CI 0.01 to 8.14) or 1.0 mg/kg urtoxazumab (74 participants: RR 0.95, 95% CI 0.79 to 1.13) reduced the incidence of HUS compared to placebo (very low certainty evidence). Low certainty evidence showed there may be little or no difference in the number of treatment-emergent adverse events with either 3.0 mg/kg urtoxazumab (71 participants: RR 1.00, 95% CI 0.84 to 1.18) or 1.0 mg/kg urtoxazumab (74 participants: RR 0.95, 95% CI 0.79 to 1.13) compared to placebo. There were 25 serious adverse events reported in 18 patients: 10 in the placebo group, and 9 and 6 serious adverse events in the 1.0 mg/kg and 3.0 mg/kg urtoxazumab groups, respectively. It is unclear how many patients experienced these adverse events in each group, and how many patients experienced more than one event. It is uncertain if either dose of urtoxazumab increased the risk of neurological complications or death (very low certainty evidence). Need for acute dialysis was not reported. AUTHORS' CONCLUSIONS: The included studies assessed antibiotics, bovine milk, and Shiga toxin inhibitor (Synsorb Pk) and monoclonal antibodies (Urtoxazumab) against Shiga toxin for secondary prevention of HUS in patients with diarrhoea due to STEC. However, no firm conclusions about the efficacy of these interventions can be drawn given the small number of included studies and the small sample sizes of those included studies. Additional studies, including larger multicentre studies, are needed to assess the efficacy of interventions to prevent development of HUS in patients with diarrhoea due to STEC infection.


Assuntos
Diarreia/complicações , Infecções por Escherichia coli/terapia , Síndrome Hemolítico-Urêmica/prevenção & controle , Prevenção Secundária/métodos , Escherichia coli Shiga Toxigênica , Adulto , Animais , Anticorpos Monoclonais Humanizados/efeitos adversos , Anticorpos Monoclonais Humanizados/uso terapêutico , Viés , Bovinos , Criança , Colostro/imunologia , Diarreia/microbiologia , Diarreia/terapia , Síndrome Hemolítico-Urêmica/epidemiologia , Humanos , Incidência , Compostos de Organossilício/efeitos adversos , Compostos de Organossilício/uso terapêutico , Placebos/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Combinação Trimetoprima e Sulfametoxazol/uso terapêutico , Trissacarídeos/efeitos adversos , Trissacarídeos/uso terapêutico
14.
Inorg Chem ; 60(15): 11672-11683, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34269564

RESUMO

New neutral iridium(III) complexes featuring a cubic polyhedral oligomeric silsesquioxane (POSS) unit, [Ir(N∧C)2(L1-POSS)] [HN∧C = 2-phenylpyridine (Hppy; 1), 2-phenylbenzothioazole (Hbt; 2), and 2-(1-naphthyl)benzothiazole (Hbsn; 3); L1-POSS = (E)-4-[(2-hydroxybenzylidene)amino]benzyl 3-heptakis(isobutyl)POSS-propyl carbamate], were designed and synthesized. Their POSS-free counterparts, [Ir(N∧C)2(L1)] [L1 = (E)-N-(4-hydroxymethylphenyl)-1-(2-hydroxyphenyl)methanimine; HN∧C = Hppy (1a), Hbt (2a), and Hbsn (3a)], and the poly(ethylene glycol) (PEG) derivatives [Ir(N∧C)2(L1-PEG)] [L1-PEG = (E)-4-[(2-hydroxybenzylidene)amino]benzyl 3-[2-[ω-methoxypoly(1-oxapropyl)]ethyl]carbamate; HN∧C = Hppy (1b), Hbt (2b), and Hbsn (3b)] were also prepared. The photophysical, photochemical, and biological properties of the POSS complexes were compared with those of their POSS-free and PEG-modified counterparts. Upon irradiation, all of these complexes displayed orange-to-red emission and long emission lifetimes under ambient conditions. The bsn complexes 3, 3a, and 3b exhibited the highest singlet oxygen (1O2) generation quantum yields (ΦΔ = 0.85-0.86) in aerated CH3CN. Laser-scanning confocal microscopy images revealed that complexes 1-3 and 1a-3a showed exclusive lipid-droplet staining upon cellular uptake, while the PEG derivatives 1b-3b displayed lysosomal localization. Complex 3 was utilized to study various lipid-droplet-related biological events including lipid-droplet accumulation under oleic acid stimulation, the movement of lipid droplets, and preadipocyte differentiation. Notably, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays indicated that the ppy complexes 1 and 1b and the bt complexes 2 and 2b were noncytotoxic both in the dark and upon irradiation at 450 nm for 5 min (IC50 > 200 µM), while the bsn complexes 3, 3a, and 3b showed low dark cytotoxicity (IC50 = 52.9 to >200 µM) and high photocytotoxicity (IC50 = 1.1-5.3 µM). The cellular uptake, internalization mechanisms, and cell death pathways of these complexes were also investigated. This work not only offers promising luminescent probes for lipid droplets through the structural modification of iridium(III) complexes but also paves the way to the construction of new reagents for theranostics.


Assuntos
Irídio/química , Gotículas Lipídicas/metabolismo , Substâncias Luminescentes/química , Imagem Molecular/métodos , Compostos de Organossilício/química , Células HeLa , Humanos , Processos Fotoquímicos , Polietilenoglicóis/química , Teoria Quântica
15.
PLoS One ; 16(7): e0254165, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34234360

RESUMO

The cellular cortex is an approximately 200-nm-thick actin network that lies just beneath the cell membrane. It is responsible for the mechanical properties of cells, and as such, it is involved in many cellular processes, including cell migration and cellular interactions with the environment. To develop a clear view of this dense structure, high-resolution imaging is essential. As one such technique, electron microscopy, involves complex sample preparation procedures. The final drying of these samples has significant influence on potential artifacts, like cell shrinkage and the formation of artifactual holes in the actin cortex. In this study, we compared the three most used final sample drying procedures: critical-point drying (CPD), CPD with lens tissue (CPD-LT), and hexamethyldisilazane drying. We show that both hexamethyldisilazane and CPD-LT lead to fewer artifactual mesh holes within the actin cortex than CPD. Moreover, CPD-LT leads to significant reduction in cell height compared to hexamethyldisilazane and CPD. We conclude that the final drying procedure should be chosen according to the reduction in cell height, and so CPD-LT, or according to the spatial separation of the single layers of the actin cortex, and so hexamethyldisilazane.


Assuntos
Actinas/química , Liofilização/métodos , Microscopia Eletrônica de Varredura/métodos , Compostos de Organossilício/química , Artefatos , Células Cultivadas , Dessecação/métodos , Humanos , Manejo de Espécimes/métodos
16.
ACS Appl Mater Interfaces ; 13(30): 36370-36379, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34297533

RESUMO

Protein micropatterning on microfabricated surfaces is a promising technology in applications for biochip microarrays, cell attachment, and biosensors. In the present work, a novel photoresponsive polymer based on light-triggered charge shifting bridged polysilsesquioxane (CBPS) is designed and prepared. The organic bridged units containing a photocleavable group of diethylaminocoumarin-4-yl in CBPS could be cleaved rapidly upon irradiation at 410 nm, resulting in the polymer surface switching from a positive charge to a negative charge property. The photoresponsive behavior of CBPS is studied using FTIR, UV-vis, SEM, fluorescence microscopy, and zeta potential analysis. Proteins are easily immobilized on the polymer surface via electrostatic interactions and released after irradiation as required. Combined with photopatterning techniques, accurate protein micropatterns are fabricated by covering a photomask upon irradiation. A gradient protein pattern is also spatially and temporally controlled by regulating irradiation parameters. This smart photoresponsive polymer surface provides a gentle and straightforward strategy to micropattern charged proteins. Moreover, the photoresponsive polymer holds permitting potential in biomedical applications such as conjugating biomolecules, guiding cell arrays, and resisting bacteria.


Assuntos
Proteínas Imobilizadas/química , Compostos de Organossilício/química , Adsorção/efeitos da radiação , Animais , Bovinos , Cumarínicos/química , Cumarínicos/efeitos da radiação , Luz , Compostos de Organossilício/efeitos da radiação , Soroalbumina Bovina/química , Eletricidade Estática , Propriedades de Superfície
17.
Int J Mol Sci ; 22(11)2021 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-34073083

RESUMO

Despite a significant number of investigations in the field of phosphazene chemistry, the formation mechanism of this class of cyclic compounds is still poorly studied. At the same time, a thorough understanding of this process is necessary, both for the direct production of phosphazene rings of a given size and for the controlled cyclization reaction when it is secondary and undesirable. We synthesized a series of short linear phosphazene oligomers with the general formula Cl[PCl2=N]n-PCl3+PCl6- and studied their tendency to form cyclic structures under the influence of elevated temperatures or in the presence of nitrogen-containing agents, such as hexamethyldisilazane (HMDS) or ammonium chloride. It was established that linear oligophosphazenes are inert when heated in the absence of the mentioned cyclization agents, and the formation of cyclic products occurs only when these agents are involved in the process. The ability to obtain the desired size phosphazene cycle from corresponding linear chains is shown for the first time. Known obstacles, such as side interaction with the PCl6- counterion and a tendency of longer chains to undergo crosslinking elongation instead of cyclization are still relevant, and ways to overcome them are being discussed.


Assuntos
Compostos Organofosforados/síntese química , Cloreto de Amônio/química , Ciclização , Compostos de Organossilício/química
18.
J Pharm Biomed Anal ; 203: 114187, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34111733

RESUMO

A series of amino-derived mixed-mode chromatographic stationary phases were synthesized based on porous mercaptopropyl-functionalized polysilsesquioxane mesoporous microspheres synthesized by a co-condensation of methyltrimethoxysilane (MTMS) and mercaptopropyltrimethoxysilane (MPTMS). Through controlling the ratio of MTMS and MPTMS, the modified stationary phases with different amino densities were prepared by a "thiol-ene" click chemistry reaction. The morphology, pore structure, and functional groups of the microspheres were characterized by scanning electron microscope (SEM), nitrogen adsorption-desorption test, Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and zeta potential, respectively. The chromatographic behavior of the stationary phases was evaluated by using alkylbenzene homologs and inorganic anions as probes. The mixed-mode retention behavior and separation mechanisms for neutral, alkaline, and acidic drugs on the prepared column had been systematically studied by changing the value of pH, ionic, and solvent strength of the mobile phase. Compared with the silica-based amino-bonded column (S-NH2), the synthesized organosilica phase exhibited higher hydrothermal stability and longer service life under high alkaline conditions. The newly synthesized phase was successfully applied to the simultaneous separation of the multiple substances in compound drugs.


Assuntos
Cromatografia de Fase Reversa , Preparações Farmacêuticas , Ânions , Interações Hidrofóbicas e Hidrofílicas , Microesferas , Compostos de Organossilício , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Cancer Sci ; 112(8): 3041-3049, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34101947

RESUMO

Near-infrared photoimmunotherapy (NIR-PIT) is a cell selective cancer therapy that uses an antibody-photoabsorber (IRDye700DX, IR700) conjugate (APC) and NIR light. NIR-PIT targeting epidermal growth factor receptor (EGFR) in head and neck cancer (HNC) was conditionally approved in Japan in 2020. APC-bound tumors can be detected using endoscopic fluorescence imaging, whereas NIR light can be delivered using endoscopic fiber optics. The aims of this study were: (1) to assess the feasibility of endoscopic NIR-PIT in an orthotopic HNC model using a CD44-expressing MOC2-luc cell line; and (2) to evaluate quantitative fluorescence endoscopic imaging prior to and during NIR-PIT. The results were compared in 3 experimental groups: (1) untreated controls, (2) APC injection without light exposure (APC-IV), and (3) APC injection followed by NIR light exposure (NIR-PIT). APC injected groups showed significantly higher fluorescence signals for IR700 compared with the control group prior to therapeutic NIR light exposure, and the fluorescence signal significantly decreased in the NIR-PIT group after light exposure. After treatment, the NIR-PIT group showed significantly attenuated bioluminescence compared with the control and the APC-IV groups. Histology demonstrated diffuse necrotic death of the cancer cells in the NIR-PIT group alone. In conclusion, endoscopically delivered light combined with quantitative fluorescence imaging can be used to "see and treat" HNC. This method could also be applied to other types of cancer approachable with endoscopy.


Assuntos
Antineoplásicos Imunológicos/administração & dosagem , Neoplasias de Cabeça e Pescoço/terapia , Receptores de Hialuronatos/antagonistas & inibidores , Indóis/administração & dosagem , Compostos de Organossilício/administração & dosagem , Administração Intravenosa , Animais , Antineoplásicos Imunológicos/química , Antineoplásicos Imunológicos/farmacologia , Linhagem Celular Tumoral , Endoscopia , Estudos de Viabilidade , Feminino , Neoplasias de Cabeça e Pescoço/imunologia , Imunoterapia , Indóis/química , Indóis/farmacologia , Camundongos , Imagem Óptica , Compostos de Organossilício/química , Compostos de Organossilício/farmacologia , Fototerapia , Ensaios Antitumorais Modelo de Xenoenxerto
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