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1.
Int J Nanomedicine ; 16: 1663-1680, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33688184

RESUMEN

Background: Intracellular tension plays a crucial role in the destruction of the blood-brain barrier (BBB) in response to lesion stimuli. Tight junction structure could be primarily affected by tension activity. In this study, we aimed to determine the effects of extracellular BBB damage on intracellular tension activity, and elucidate the mechanism underlying the effects of intracellular protein nanoparticle-related osmotic pressure on BBB permeability. Methods: The intracellular tension for tight junction proteins occludin and ZO1 was evaluated using the fluorescence resonance energy transfer (FRET)-based tension probes and cpstFRET analysis. The changes in mobility ratios of occludin were evaluated via the fluorescence recovery after photobleaching (FRAP) test. The cytoplasmic osmotic pressure (OP) was measured using Osmometer. The count rate of cytoplasmic nanoparticles was detected by Nanosight NS300. The activation of cofilin and stathmin was examined by Western blot analysis. The BBB permeability in vivo was determined via the changes of Evans Blue (EB) injected into SD rats. The tight junction formation was assessed by the measurement of transendothelial electrical resistance (TEER). Intracellular calcium or chloride ions were measured using Fluo-4 AM or MQAE dyes. Results: BBB lesions were accompanied by changes in occludin/ZO1 tension. Increases in intracellular osmotic pressure were involved in alteration of BBB permeability, possibly through the depolymerization of microfilaments or microtubules and mass production of protein nanoparticles according to the Donnan effect. Recovery of protein nanoparticle-related osmotic pressure could effectively reverse the effects of changes in occludin/ZO1 tension under BBB lesions. Outward tension of intracellular osmotic potential also caused upregulation of membrane fluidity, which promoted nonselective drug influx. Conclusion: Our results suggest a crucial mechanical mechanism underlying BBB lesions, and protein nanoparticle-related osmotic pressure could be a novel therapeutic target for BBB lesion-related brain diseases.


Asunto(s)
Barrera Hematoencefálica/metabolismo , Fluidez de la Membrana , Nanopartículas/química , Presión Osmótica , Proteínas/química , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/metabolismo , Animales , Barrera Hematoencefálica/efectos de los fármacos , Línea Celular , Azul de Evans/metabolismo , Humanos , Masculino , Fluidez de la Membrana/efectos de los fármacos , Microtúbulos/efectos de los fármacos , Microtúbulos/metabolismo , Ocludina/metabolismo , Presión Osmótica/efectos de los fármacos , Permeabilidad , Fitoquímicos/farmacología , Polimerizacion , Ratas Sprague-Dawley , Uniones Estrechas/efectos de los fármacos , Uniones Estrechas/metabolismo , Proteína de la Zonula Occludens-1/metabolismo
2.
Science ; 371(6535): 1225-1232, 2021 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-33737482

RESUMEN

Early life is thought to have required the self-replication of RNA by RNA replicases. However, how such replicases evolved and subsequently enabled gene expression remains largely unexplored. We engineered and selected a holopolymerase ribozyme that uses a sigma factor-like specificity primer to first recognize an RNA promoter sequence and then, in a second step, rearrange to a processive elongation form. Using its own sequence, the polymerase can also program itself to polymerize from certain RNA promoters and not others. This selective promoter-based polymerization could allow an RNA replicase ribozyme to define "self" from "nonself," an important development for the avoidance of replicative parasites. Moreover, the clamp-like mechanism of this polymerase could eventually enable strand invasion, a critical requirement for replication in the early evolution of life.


Asunto(s)
Regiones Promotoras Genéticas , ARN Catalítico , ARN/química , ARN/metabolismo , Evolución Molecular Dirigida , Evolución Molecular , Mutación , Conformación de Ácido Nucleico , Polimerizacion , Dominios Proteicos , ARN/genética , ARN Catalítico/química , ARN Catalítico/genética , ARN Catalítico/metabolismo , /genética , Factor sigma/metabolismo
3.
J Chromatogr A ; 1641: 462012, 2021 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-33647538

RESUMEN

Synthesis and applications of molecularly imprinted polymers (MIP) are rapidly growing. In this study, a biomimetic MIP was prepared through silanes polymerization on the surface of 96-well microplates using recombinant human erythropoietin-alfa (rhEPO) as a template molecule. The rhEPO was immobilized onto the plate surface using bi-functional cross-linker and a thin imprinted layer following sol-gel procedure was constructed. After template extraction, uniform three-dimensional cavities compatible with the configuration of rhEPO were obtained. The rhEPO-MIP preparation was optimized using 2-level factorial design and response surface design where polymerization time and interactions between the different variable were found to be the most significant factors. Size-exclusion chromatography (SEC) was used to monitor the stability of the rhEPO under the investigated polymerization conditions. Determination of rhEPO using the MIP microplate showed good dynamic response fitting to the 4 PL regression model (0.9962) over a concentration range of 10.00 - 100.00 ng mL-1. Adsorption of rhEPO onto MIP followed the Langmuir isotherm model (r = 0.9957, χ2 =0.02786) with pseudo-second-order kinetics (r = 0.9984). The surface of the rhEPO-MIP was characterized using scanning electron microscopy (SEM) while step-by-step surface modification was tracked using Fourier transform infrared (FTIR) spectroscopy. The rhEPO-MIP was able to distinguish between the rhEPO-alfa template and modified rhEPO molecules; rhEPO-beta, hyperglycosylated and pegylated forms (imprinting factors < 2) and in the commonly used formulation additive human serum albumin (HSA) (R% = 113.96 -95.22%). The rhEPO-MIP was applied to compare the receptor-binding pattern to rhEPO and its biosimilars / structural analogues. The results were cross-validated using the conventional assay protocol (RP-HPLC and ELISA) and an acceptable correlation was observed with RP-HPLC (maximum deviation is 7.78%). This work confirmed the applicability of rhEPO-MIP with its unique binding features for batch release, stability and biosimilarity assessment as well as subsequent evaluation of batch-to-batch consistency during bioproduction of target analytes.


Asunto(s)
Biosimilares Farmacéuticos/análisis , Eritropoyetina/análisis , Impresión Molecular/instrumentación , Proteínas Recombinantes/análisis , Adsorción , Cromatografía en Gel , Cromatografía Líquida de Alta Presión , Cromatografía de Fase Inversa , Ensayo de Inmunoadsorción Enzimática , Humanos , Concentración de Iones de Hidrógeno , Polimerizacion , Análisis de Regresión , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier
4.
Dental Press J Orthod ; 26(1): e2119150, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33729290

RESUMEN

INTRODUCTION: Third generation of LED light curing units might be used in short exposure periods for orthodontic brackets bonding. OBJECTIVE: This study evaluated the effect of the different radiant exposure (RE) values: Manufacturers' instructions (MI), ½ MI, 1/4 MI and Turbo mode. Two third-generation LED curing units were used: VALO® and Bluephase 20i® . The degree of conversion (DC) and Vickers hardness (VHN) of an orthodontic composite (OC) (Transbond XT) under metallic (MB) or ceramic brackets (CB) were measured. METHODS: OC was applied to the bracket base, which was then placed over an attenuated total reflectance (ATR) table coupled to an infrared light spectroscope, or to a glass surface for the VHN analysis. The specimens were light-cured and DC values were calculated. The VHN was obtained in a microhardness tester. The data were analyzed with 2-way ANOVA followed by Tukey's post-hoc test (pre-set α=0.05). Linear regression analysis evaluated the relationship between RE values and dependent variables. RESULTS: CB allowed higher DC and VHN values than MB (p< 0.001). No significant difference was noted among groups when CB were used. For MB, MI groups showed the highest DC and VHN values. A significant, but weak relationship was found between delivered RE values and dependent variables. CONCLUSIONS: The decrease in RE values from third generation LED CU did not jeopardize the DC values when CB were used, but can compromise DC and VHN values when MB are used.


Asunto(s)
Luces de Curación Dental , Soportes Ortodóncicos , Cerámica , Resinas Compuestas , Dureza , Ensayo de Materiales , Polimerizacion , Cementos de Resina , Propiedades de Superficie
5.
Nat Commun ; 12(1): 1741, 2021 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-33741912

RESUMEN

Natural biomolecular assemblies such as actin filaments or microtubules can exhibit all-or-nothing polymerization in a kinetically controlled fashion. The kinetic barrier to spontaneous nucleation arises in part from positive cooperativity deriving from joint-neighbor capture, where stable capture of incoming monomers requires straddling multiple subunits on a filament end. For programmable DNA self-assembly, it is likewise desirable to suppress spontaneous nucleation to enable powerful capabilities such as all-or-nothing assembly of nanostructures larger than a single DNA origami, ultrasensitive detection, and more robust algorithmic assembly. However, existing DNA assemblies use monomers with low coordination numbers that present an effective kinetic barrier only for slow, near-reversible growth conditions. Here we introduce crisscross polymerization of elongated slat monomers that engage beyond nearest neighbors which sustains the kinetic barrier under conditions that promote fast, irreversible growth. By implementing crisscross slats as single-stranded DNA, we attain strictly seed-initiated nucleation of crisscross ribbons with distinct widths and twists.


Asunto(s)
ADN/química , Polimerizacion , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Citoesqueleto/metabolismo , ADN de Cadena Simple , Cinética , Microtúbulos/metabolismo
6.
Nat Cell Biol ; 23(2): 147-159, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33558729

RESUMEN

Coordinated polymerization of actin filaments provides force for cell migration, morphogenesis and endocytosis. Capping protein (CP) is a central regulator of actin dynamics in all eukaryotes. It binds to actin filament (F-actin) barbed ends with high affinity and slow dissociation kinetics to prevent filament polymerization and depolymerization. However, in cells, CP displays remarkably rapid dynamics within F-actin networks, but the underlying mechanism remains unclear. Here, we report that the conserved cytoskeletal regulator twinfilin is responsible for CP's rapid dynamics and specific localization in cells. Depletion of twinfilin led to stable association between CP and cellular F-actin arrays, as well as to its retrograde movement throughout leading-edge lamellipodia. These were accompanied by diminished F-actin turnover rates. In vitro single-filament imaging approaches revealed that twinfilin directly promotes dissociation of CP from filament barbed ends, while enabling subsequent filament depolymerization. These results uncover a bipartite mechanism that controls how actin cytoskeleton-mediated forces are generated in cells.


Asunto(s)
Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Proteínas de Microfilamentos/metabolismo , Seudópodos/metabolismo , Adenosina Difosfato/metabolismo , Animales , Recuperación de Fluorescencia tras Fotoblanqueo , Proteínas Fluorescentes Verdes/metabolismo , Ratones , Ratones Noqueados , Proteínas de Microfilamentos/genética , Mutación/genética , Polimerizacion
7.
Sci Total Environ ; 772: 145074, 2021 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-33581516

RESUMEN

The molecularly imprinted polymers (MIPs) with the following herbicides used as templates 2,4-dichlorophenoxyacetic acid (2,4-D) or 4-chloro-2-methylphenoxy- acetic acid (MCPA) were synthesized by precipitation polymerization technique using 4-vinylpyridine (4-VP) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent, and 2,2'-azobisisobutyronitrile (AIBN) as an initiator in methanol solvent. For the flavonoid MIPs, rutin (Ru) and quercetin (Q) were used as templates and synthesized via a similar technique, utilizing acrylamide (AA) as a functional monomer. Analysis of binding in the molecularly imprinted and non-imprinted polymer (NIP) has proved that MIP shows a higher affinity towards the analytes, compared to NIP. MIP was used to determine analytes in water using the Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (FAPA-MS) technique. In this approach, the method limit of detection (MLOD) of 2,4-D, MCPA, Ru, and Q in MIP was 4, 3, 10, and 5 µg in 1 g MIP, respectively. The release kinetics of the analytes from MIP and their stability in water was studied. The cultures of Tetradesmus obliquus (Turpin) M.J. Wynne and Daphnia magna Straus were used for in vivo toxicity studies revealing that only Ru-MIP and Q-MIP had negative effect on the living organisms used in the bioassays.


Asunto(s)
Impresión Molecular , Espectrometría de Masas , Polimerizacion , Polímeros
8.
Food Chem ; 349: 129209, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33588184

RESUMEN

Porphyra is one of the most economically important red algae in the world. The functional components extracted from Porphyra such as porphyrans, proteins, lipids, and minerals have strong physiological activities. Porphyran, a sulfated galactan, is composed of alternating 1,4-linked α-l-galactopyranose-6-sulfate (L6S) and 1,3-linked ß-d-galactopyranose (G). Porphyran and oligo-porphyran have a series of pharmacological and biological functions, such as antioxidation, anticancer, antiaging, antiallergic, immunomodulatory, hypoglycaemic, and hypolipidemic effects. Thus, red algae Porphyra-derived porphyran and oligo-porphyran have various potential applications in food, medicine, and cosmetic fields. For better application, this review introduces and summarizes the structure and source of porphyran as well as the preparation methods, biological activities, and potential applications of porphyran and oligo-porphyran. Moreover, the future research directions and emphasis of porphyran and oligo-porphyran preparation as well as their functional activities and applications are highlighted and prospected.


Asunto(s)
Polimerizacion , Porphyra/química , Sefarosa/análogos & derivados , Antioxidantes/química , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Sefarosa/química , Sefarosa/aislamiento & purificación , Sefarosa/farmacología
9.
J Chromatogr A ; 1640: 461948, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33561708

RESUMEN

Fast-throughput and cost reduction of current purification platforms are becoming increasing requests during antibody manufacture. The macroporous-matrix absorbents have presented extensive potentiality in improving operational throughput during purification of macromolecule. And meanwhile the peptide ligand has become a promising alternative to recombinant protein ligands for cost reduction of chromatographic purification. Therefore, here we designed a functionalized microspheres resin with both macroporous matrix of polymerized glycidyl methacrylate and ethylene glycol dimethacrylate (PGMA-EDMA) and peptide ligand of hexapeptide (FYEILH). In order to circumvent the steric effect of peptides and amplify the binding sites on macroporous matrix, the peptide ligand was coupled on a liner PGMA polymer brushes grafted on microspheres. Comparing to the conventional agarose-matrix resin and the general peptide-grafted microspheres, the functionalized microspheres presented excellent permeability and high capacity to rapid loading hIgG by maintaining a stable level of dynamic binding capacity at fast flow rate above 110 column volume per hour (cv/h) and very short residence time below 0.5 min. Such functionalized microspheres provide a facile and broadly applicable strategy to develop the attractive candidate for rapid and cost-reduced purification of antibody.


Asunto(s)
Anticuerpos Monoclonales/aislamiento & purificación , Inmunoglobulina G/aislamiento & purificación , Microesferas , Péptidos/química , Polímeros/química , Adsorción , Animales , Células CHO , Cromatografía , Cricetulus , Difusión , Humanos , Ligandos , Permeabilidad , Polimerizacion , Porosidad , Dominios Proteicos , Proteínas Recombinantes/química , Resinas Sintéticas/química , Sefarosa/química , Albúmina Sérica Bovina/química , Proteína Estafilocócica A/química , Propiedades de Superficie
10.
N Engl J Med ; 384(6): 512-520, 2021 02 11.
Artículo en Inglés | MEDLINE | ID: mdl-33567191

RESUMEN

BACKGROUND: The tubulin polymerization and Src kinase signaling inhibitor tirbanibulin is being investigated as a topical treatment for actinic keratosis, a precursor of squamous-cell carcinoma. METHODS: In two identically designed double-blind trials, we randomly assigned, in a 1:1 ratio, adults with actinic keratoses on the face or scalp to receive either topical tirbanibulin or vehicle (placebo) ointment. The ointment was applied by the patients to a 25-cm2 contiguous area containing four to eight lesions once daily for 5 consecutive days. The primary outcome was the percentage of patients with a complete (100%) reduction in the number of lesions in the application area at day 57. The secondary outcome was the percentage of patients with a partial (≥75%) reduction in the number of lesions within the application area at day 57. The incidence of recurrence was evaluated at 1 year. Local reactions were scored with the use of 4-point scale (ranging from 0 [absent] to 3 [severe]). RESULTS: A total of 702 patients were enrolled in the two trials (351 patients per trial). Complete clearance in trial 1 occurred in 44% of the patients (77 of 175) in the tirbanibulin group and in 5% of those (8 of 176) in the vehicle group (difference, 40 percentage points; 95% confidence interval [CI], 32 to 47; P<0.001); in trial 2, the percentages were 54% (97 of 178 patients) and 13% (22 of 173), respectively (difference, 42 percentage points; 95% CI, 33 to 51; P<0.001). The percentages of patients with partial clearance were significantly higher in the tirbanibulin groups than in the vehicle groups. At 1 year, the estimated percentage of patients with recurrent lesions was 47% among patients who had had a complete response to tirbanibulin. The most common local reactions to tirbanibulin were erythema in 91% of the patients and flaking or scaling in 82%. Adverse events with tirbanibulin were application-site pain in 10% of the patients and pruritus in 9%, all of which resolved. CONCLUSIONS: In two identically designed trials, tirbanibulin 1% ointment applied once daily for 5 days was superior to vehicle for the treatment of actinic keratosis at 2 months but was associated with transient local reactions and recurrence of lesions at 1 year. Trials comparing tirbanibulin with conventional treatments and that have longer follow-up are needed to determine the effects of tirbanibulin therapy on actinic keratosis. (Funded by Athenex; ClinicalTrials.gov numbers, NCT03285477 and NCT03285490.).


Asunto(s)
Acetamidas/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Queratosis Actínica/tratamiento farmacológico , Morfolinas/uso terapéutico , Piridinas/uso terapéutico , Acetamidas/efectos adversos , Administración Tópica , Anciano , Método Doble Ciego , Inhibidores Enzimáticos/efectos adversos , Cara/patología , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Morfolinas/efectos adversos , Pomadas/uso terapéutico , Polimerizacion/efectos de los fármacos , Piridinas/efectos adversos , Cuero Cabelludo/patología , Piel/patología , Tubulina (Proteína)/metabolismo
11.
ACS Appl Mater Interfaces ; 13(7): 8060-8070, 2021 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-33576220

RESUMEN

The high activity of specific enzymes in cancer has been utilized in cancer diagnosis, as well as tumor-targeted drug delivery. NAD(P)H:quinone oxidoreductase-1 (NQO1), an overexpressed enzyme in certain tumor types, maintains homeostasis and inhibits oxidative stress caused by elevated reactive oxygen species (ROS) in tumor cells. The activity of NQO1 in lung and liver cancer cells is increased compared to that in normal cells. Interestingly, NQO1 reacts with trimethyl-locked quinone propionic acid (QPA) and produces a lactone-based group via intramolecular cyclization. Toward this objective, we synthesized an amphiphilic block copolymer (QPA-P) composed of NQO1 enzyme-triggered depolymerizable QPA-locked polycaprolactone (PCL) and poly(ethylene glycol) (PEG) as hydrophobic and hydrophilic constituents, respectively. This QPA-P formed self-assembled micelles in aqueous conditions. It was observed that NQO1 catalyzed the depolymerization of QPA-locked PCL via a cascade two-step cyclization process, which eventually induced the dissociation of micellar structure and triggered the release of loaded drugs at the target cancer cells. Compared to the control group, the NQO1-responsive micelle showed NQO1-triggered intracellular drug release and enhanced anticancer effects. These results indicate that the NQO1-responsive polymeric micelles present a promising potential for improving therapeutic efficacy of an anticancer drug delivery system.


Asunto(s)
Antibióticos Antineoplásicos/farmacología , Doxorrubicina/farmacología , Sistemas de Liberación de Medicamentos , Neoplasias Pulmonares/tratamiento farmacológico , NAD(P)H Deshidrogenasa (Quinona)/metabolismo , Polímeros/metabolismo , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/metabolismo , Benzoquinonas/química , Benzoquinonas/metabolismo , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Ciclización , Doxorrubicina/química , Doxorrubicina/metabolismo , Liberación de Fármacos , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Lactonas/química , Lactonas/metabolismo , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Micelas , Estructura Molecular , NAD(P)H Deshidrogenasa (Quinona)/química , Tamaño de la Partícula , Polimerizacion , Polímeros/química , Propionatos/química , Propionatos/metabolismo , Propiedades de Superficie , Células Tumorales Cultivadas
12.
Int J Nanomedicine ; 16: 1021-1036, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33603366

RESUMEN

Purpose: To investigate the role and activation mechanism of TAZ in periodontal ligament stem cells (PDLSCs) perceiving hierarchical microgroove/nanopore topography. Materials and Methods: Titanium surface with hierarchical microgroove/nanopore topography fabricated by selective laser melting combined with alkali heat treatment (SLM-AHT) was used as experimental group, smooth titanium surface (Ti) and sandblasted, large-grit, acid-etched (SLA) titanium surface were employed as control groups. Alkaline phosphatase (ALP) activity assays, qRT-PCR, Western blotting, and immunofluorescence were carried out to evaluate the effect of SLM-AHT surface on PDLSC differentiation. Moreover, TAZ activation was investigated from the perspective of nuclear localization to transcriptional activity. TAZ knockdown PDLSCs were seeded on three titanium surfaces to detect osteogenesis- and adipogenesis-related gene expression levels. Immunofluorescence and Western blotting were employed to investigate the effect of the SLM-AHT surface on actin cytoskeletal polymerization and MAPK signaling pathway. Cytochalasin D and MAPK signaling pathway inhibitors were used to determine whether actin cytoskeletal polymerization and the MAPK signaling pathway were indispensable for TAZ activation. Results: Our results showed that SLM-AHT surface had a greater potential to promote PDLSC osteogenic differentiation while inhibiting adipogenic differentiation than the other two groups. The nuclear localization and transcriptional activity of TAZ were strongly enhanced on the SLM-AHT surface. Moreover, after TAZ knockdown, the enhanced osteogenesis and decreased adipogenesis in SLM-AHT group could not be observed. In addition, SLM-AHT surface could promote actin cytoskeletal polymerization and upregulate p-ERK and p-p38 protein levels. After treatment with cytochalasin D and MAPK signaling pathway inhibitors, differences in the TAZ subcellular localization and transcriptional activity were no longer observed among the different titanium surfaces. Conclusion: Our results demonstrated that actin cytoskeletal polymerization and MAPK signaling pathway activation triggered by SLM-AHT surface were essential for TAZ activation, which played a dominant role in SLM-AHT surface-induced stem cell fate decision.


Asunto(s)
Diferenciación Celular , Nanoporos , Células Madre/citología , Transactivadores/metabolismo , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/metabolismo , Adipogénesis/efectos de los fármacos , Adhesión Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Modelos Biológicos , Osteogénesis/efectos de los fármacos , Ligamento Periodontal/citología , Polimerizacion , Propiedades de Superficie , Titanio/farmacología
13.
J Chromatogr A ; 1639: 461928, 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33524934

RESUMEN

A temperature-responsive solid-phase microextraction (SPME) coating was prepared via in-situ atom transfer radical polymerization (ATRP) method. By controlling the temperature of solution below and above the lower critical solution temperature (LCST) of the coating, it can switch between hydrophilic and hydrophobic, thus providing a convenient approach for the selective extraction of analytes with different polarities. The average extraction amount of temperature-responsive coating for polar analytes is about 1.5-fold to that of non-polar ones below LCST, and vice versa. Effective extraction of three biomacromolecules was also obtained by controlling the temperature below or above LCST. The adsorption capacity of the coating for the hydrophilic biomacromolecules at 15 °C is 1.5-2 folds that of 50 °C, whereas the adsorption capacity of the coating to BSA at 50 °C is about 3 folds that of 15 °C. This approach holds great promise for SPME because it provides a simple strategy to prepare bifunctional coatings for various applications.


Asunto(s)
Hidrogeles/química , Microextracción en Fase Sólida/métodos , Temperatura , Adsorción , Interacciones Hidrofóbicas e Hidrofílicas , Polimerizacion , Espectroscopía Infrarroja por Transformada de Fourier , Agua/química
14.
Food Chem ; 349: 129174, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33548884

RESUMEN

Hydrochloric acid (HCl) is widely used to prepare pyrodextrins, especially the water-soluble pyrodextrin. In this study, the structural difference between pyrodextrins as affected by HCl is compared by characterizing the molecular size, chain-length distributions (CLDs), crystallinity, and solubility. It is found that: 1) dry heating of starch granules without HCl mainly degrades long-amylose chains while slightly affects amylopectin branches; 2) the presence of HCl during dry heating decreases the degree of polymerization (DP) range of amylose chains upon degradation from DP ~ 833-1267 to DP ~ 206-432, suggesting that the presence of HCl accelerates the breakdown of long-amylose chains; 3) both pyroconversion processes have slight effects on A-(DP ~ 6-12) and B1- chains (DP ~ 12-24), which might explain the retained granular and crystalline structure during the process. This study could improve the understanding of the role of HCl in affecting the structure and property during pyroconversion of native starch.


Asunto(s)
Amilosa/química , Dextrinas/química , Ácido Clorhídrico/química , Amilopectina/química , Polimerizacion , Solubilidad , Almidón/química , Temperatura
15.
Food Chem ; 350: 129260, 2021 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-33618093

RESUMEN

Oligomers, are, in general, unknown components of the polymer. These oligomers can migrate from the polymer into the food and become a non-intentionally added substance to the food. In this work, ion mobility time-of-flight mass spectrometry has been used to identify oligomers migrating from kitchenware. The structure elucidation of oligomers from polyamide 6 and polyamide 66 was achieved through the analysis of accurate m/z values of adducts and collision cross section values of precursor ions together with high-energy fragmentation patterns. Additionally, a method to extract oligomers from sunflower oil, cooked beans, soup and whole milk has been developed. Extraction recoveries ranged from 87 to 102% and limits of detection were from 0.03 to 0.11 mg/kg. It was observed that the migration from kitchenware to real food was below the specified migration limit of 5 mg/kg. However, this limit was exceeded for food simulants, which therefore overestimated the oligomer migration.


Asunto(s)
Caprolactama/análogos & derivados , Contaminación de Alimentos/análisis , Espectrometría de Movilidad Iónica/métodos , Polimerizacion , Polímeros/química , Animales , Caprolactama/química , Leche/química
16.
Food Chem ; 347: 129040, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33484960

RESUMEN

An Ultra High-Performance Liquid chromatography method quadruple time-of-flight mass spectrometry has been developed for the analysis of 11 cyclic polyesters oligomers, following a modified QuEChERS clean-up with alumina/primary secondary amine, in pasta. Target analytes were polyethylene terephthalate (PET) 1st series cyclic dimer to heptamer, polybutylene terephthalate (PBT) dimer to pentamer and a polyurethane oligomer. Standard addition method was applied for the calibration, and the limits of quantification ranged from 3.2 to 17.2 ng g-1. Recoveries ranged from 86.4 to 109.8%, RSDs were lower than 12% for all analytes, and matrix effect never exceeded ± 2.5%. The method was successfully applied to real commercial pasta samples, where the PET 1st series cyclic trimer was the most abundant oligomer, being found in all tested samples. The 1st series PET cyclic dimer and tetramer, as well as 1,4,7-trioxacyclotridecane-8,13-dione, were found in considerable amounts. Traces of the 2nd and 3rd series PET cyclic dimers were also found.


Asunto(s)
Análisis de los Alimentos/métodos , Espectrometría de Masas/métodos , Poliésteres/química , Tereftalatos Polietilenos/química , Óxido de Aluminio/química , Cromatografía Líquida de Alta Presión , Dimerización , Harina/análisis , Poliésteres/análisis , Tereftalatos Polietilenos/análisis , Polimerizacion , Dióxido de Silicio/química
17.
ACS Appl Mater Interfaces ; 13(4): 5877-5886, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33482691

RESUMEN

Chiral carbon dots (CDs) integrated the advantages of achiral CDs and the unique chiral property, which expand the prospect of the biological applications of CDs. However, the structure control and the origin of chirality for chiral CDs remain unclear. Herein, chiral CDs were obtained by thermal polymerization of chiral amino acids and citric acid, and their handedness of chirality could be controlled by adjusting the reaction temperature, which leads to different kinds of surface modifications. With aliphatic amino acids as a chiral source, all of the CDs that reacted at different temperatures (90-200 °C) have the same handedness of the chiral source. But with aromatic amino acids as a chiral source, CDs with maintained or inversed handedness compared with the chiral source could be obtained by adjusting the reaction temperature. Below a temperature of 120 °C, the chiral source was modified with CDs by esterification and transferred the handedness of chirality; at high temperatures (above 150 °C), which mainly connected by amidation accompanying with the formation of rigid structure generated by the π conjugation between the aromatic nucleus of chiral source and the carbon core of CDs, caused the inversing of the chiral signal. Further, we investigated the chiral effects of CDs on the glucose oxidase activity for a highly sensitive electrochemical biosensor.


Asunto(s)
Aminoácidos/química , Técnicas Biosensibles/métodos , Glucosa Oxidasa/química , Glucosa/análisis , Puntos Cuánticos/química , Carbono/química , Ácido Cítrico/química , Estabilidad de Enzimas , Esterificación , Modelos Moleculares , Polimerizacion , Puntos Cuánticos/ultraestructura , Estereoisomerismo , Propiedades de Superficie
18.
J Chromatogr A ; 1638: 461851, 2021 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-33434813

RESUMEN

To allow an enhanced understanding of the order in packed HPLC columns, in this work a methodology for immobilizing native polar silica particles is developed based on the polymerization of a methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the interstitial pores of HPLC columns. Subsequent mechanical cutting then allows scanning electron microscopy (SEM) based imagery of cross-sections of the packed bed. In this way, the packing efficiency of home-made and commercial HPLC columns with 4.6 mm inner diameter and 150 mm length comprising the same packing material of 5 µm silica particles are compared. The methodology is developed for native silica used in e.g. hydrophilic interaction liquid chromatography (HILIC) and in normal phase LC. In order to confirm the feasibility of the developed methodology, the conventional methods for the evaluation of column, efficiency and porosity, are also employed. The obtained porosity information is compared and showed the same trend with the external porosity measurements obtained via inverse size exclusion approach, illustrating its potential application to study the micro-heterogeneity of packed HPLC columns and to guide the optimization of the packing process of HPLC columns.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Microscopía Electrónica de Rastreo , Metacrilatos/química , Metilmetacrilato/química , Tamaño de la Partícula , Polimerizacion , Porosidad , Dióxido de Silicio/química
19.
Nat Commun ; 12(1): 446, 2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33469013

RESUMEN

Complex biological tissues are highly viscoelastic and dynamic. Efforts to repair or replace cartilage, tendon, muscle, and vasculature using materials that facilitate repair and regeneration have been ongoing for decades. However, materials that possess the mechanical, chemical, and resorption characteristics necessary to recapitulate these tissues have been difficult to mimic using synthetic resorbable biomaterials. Herein, we report a series of resorbable elastomer-like materials that are compositionally identical and possess varying ratios of cis:trans double bonds in the backbone. These features afford concomitant control over the mechanical and surface eroding degradation properties of these materials. We show the materials can be functionalized post-polymerization with bioactive species and enhance cell adhesion. Furthermore, an in vivo rat model demonstrates that degradation and resorption are dependent on succinate stoichiometry in the elastomers and the results show limited inflammation highlighting their potential for use in soft tissue regeneration and drug delivery.


Asunto(s)
Implantes Absorbibles , Materiales Biocompatibles/química , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Células 3T3 , Animales , Línea Celular , Elastómeros , Femenino , Humanos , Ensayo de Materiales , Células Madre Mesenquimatosas , Ratones , Polimerizacion , Ratas , Estereoisomerismo , Propiedades de Superficie , Resistencia a la Tracción
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