Enzyme-polymer hybrid layers for self-cleaning surfaces

This work focused on the generation and characterization of ultrathin coatings with a self-cleaning ability. The general idea was to immobilize a typical detergent enzyme on model surfaces in a way that retains the activity of the enzyme. The specific system under investigation was a hydrogel coating which was chemically anchored on the surface and which also served as a carrier for the enzyme. The hydrogel coating was prepared from water-soluble polymers that carry a small percentage of photo-reactivegroups suitable for reaction with neighbouring chains in a way that leads to crosslinking. Similar groups on the surface provide a surface anchoring of the layers by theestablishment of covalent bonds between the two components. Amylase was chosen as the enzyme because it is readily available and it cleaves carbohydrates which are typically present in many surface stains. The resulting molecules are smaller and typicallymore soluble in water such that a stain containing such components is more easily rinsed off the surface.\nThis enzyme was to be incorporated into the hydrogel carrier coating by means of co-deposition via dip coating. Thesubsequent UV crosslinking whichlead to a surface anchoring not only of the film but also of the enzyme by means of either physical entrapment or chemical anchoring through the surface reaction.\nPrevious finding suggested an insufficient anchoring of enzymes via this route as the enzyme needs to be deposited from buffer solutions which contain high amounts of salt. This is also deposited and keeps much of the enzyme from being incorporated into the hydrogel coating. For this reason the enzyme was modified with another hydrophilic polymer, Polyethylene glycol chains were chemically attached to the amylase via an active ester. Using this procedure the amylase was rendered soluble in ethanol without losing anyactivity and overall increased in enzymatic activity as compared to the native enzyme.\nAn investigation of the coating procedure by various techniques revealed indeed that the route via PEGylated amylase and deposition from ethanol in the absence of any salt yielded much smoother layers in which the enzyme was rather homogenously distributed. Control coatings generated from native amylase and deposited from PBS buffer gave very rough coatings that were covered with salt crystals.\nA comparison of the enzymatic activity via colorimetric measurements first demonstrated that enzymaticallycoatings could be generated via both routes. The coatings prepared from PEG-conjugated amylase however were always more active than those prepared from native amylase and they also retained this active character better if exposed to UV light or heat.\nA simple self-cleaning test also showed that coatings prepared from native amylase lost their initially good self-cleaning character after a first rinse. Repeated use of such samples was not possible. The coatings carrying PEGylated enzyme also lost much of their initial activity after the first test but repeated use was possible and clear degradation of starch in a test involving mayonnaise was clearly visible.\nThe general concept of enzyme carrying coatings based on surface-attached hydrogels was successfully demonstrated. Further investigations should concentrate on the analysis of the influence of the deposition conditions on the enzyme activity. Such investigations should include a more thorough characterization of the resulting layers. Such research may eventually lead to self-cleaning surfaces that are stable on a time scale which is suitable at least for delicate applications e.g. in a biomedical environment.\nFil: Shah, Urmil. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaEste trabajo se centró en la generación y caracterización de recubrimientos ultrafinos con capacidad autolimpiante. El objetivo general fue inmovilizar una enzima detergente típica en superficies modelo a través de un procedimiento que permitiera conservar la actividad enzimática. El sistema específico bajo investigación fue un recubrimiento de hidrogel capaz de unirse químicamente a la superficie y simultáneamente servir como vehículo para la enzima. El recubrimiento de hidrogel se preparó a partir de polímeros solubles en agua con un pequeño porcentaje de grupos fotorreactivos adecuados para reacciones de entrecruzamiento entre cadenas vecinas. Grupos similares en el recubrimiento proporcionan un anclaje para el establecimiento de enlaces covalentes con la enzima. La enzima amilasa fue elegida por su amplia disponibilidad y su capacidad de degradar hidratos de carbono. Los hidratos de carbono son moléculas típicamente presentes en muchas manchas de superficie y como resultado de la acción de la amilasa se producen moléculas más pequeñas y generalmente más solubles, de manera que una mancha que contiene estos componentes se elimina más fácilmente.\nLa enzima fue incorporada en el recubrimiento de hidrogel por co-deposición mediante inmersión. Posteriormente, a través de la exposición a radiación UV se generó un entrecruzamiento que condujo al anclaje, no solo de la película a la superficie, sino también de la enzima a la película, a través de atrapamiento físico o anclaje químico.\nEstudios previos indicaron un anclaje insuficiente de las enzimas cuando el proceso se realizaba a través de esta técnica de co-deposición con inmersión, dado que la enzima era depositada a partir de soluciones buffer con altas cantidades de sal, que también se depositaba sobre la superficie. Este fenómeno impedía la incorporación de gran parte de la enzima al recubrimiento de hidrogel. Por esta razón la enzima se modificó con otro polímero hidrófilo, el polietilenglicol (PEG). Se unieron químicamente cadenas de PEG a la amilasa a través de un éster activo. Utilizando este procedimiento, la amilasa se solubilizó en etanol sin perder actividad.\nSe investigaron diversas técnicas de recubrimiento y se demostró que la utilización de la amilasa conjugada con PEG y la deposición a partir de etanol en ausencia de cualquier sal produjo recubrimientos con una distribución homogénea de la enzima y de características muy lisas, mientras que los recubrimientos generados con amilasa nativa depositada a partir de solución buffer salina dieron origen a recubrimientos muy ásperos y cubiertos con cristales de sal.\nUn análisis comparativo de la actividad enzimática, a través de mediciones colorimétricas, demostró que los recubrimientos tenían actividad enzimática, cualquiera fuera el procedimiento utilizado para su generación. Los recubrimientos preparados a partir de amilasa conjugada con PEG mostraron siempre mayor actividad que los preparados a partir de amilasa nativa y retuvieron mejor la actividad enzimática después de la exposición a radiación UV o calor.\nA través de una prueba de autolimpieza sencilla se demostró que los recubrimientos preparados a partir de amilasa nativa perdieron su propiedad autolimpiante, inicialmente buena, después de un primer enjuague. El uso repetido de dichos recubrimientos no fue posible. Los recubrimientos producidos con la amilasa conjugada con PEG también perdieron gran parte de su actividad autolimpiante inicial después del primer enjuague, pero fueron reutilizables. Se utilizó un ensayo de degradación del almidón en una muestra de mayonesa para estos estudios.\nEl objetivo general del recubrimiento de hidrogel con enzimas unidas a superficie se cumplió exitosamente en este trabajo. Investigaciones futuras se deberán enfocar en el análisis de la influencia de las condiciones de deposición sobre la actividad de la enzima. Esas investigaciones deberían incluir una caracterización más profunda de la estructura del recubrimiento resultante. Este tipo de investigación podría conducir eventualmente a desarrollar superficies autolimpiantes estables en escalas de tiempo adecuadas para aplicaciones específicas, por ejemplo, en el entorno biomédico

Design of polyphosphoester coplymers as scaffolds for tissue engineering applications

Polymers with repeating phosphoester linkages in the backbone are biodegradable and emerged as a promising class of novel biomaterials. In contrast to polyesters, the pentavalency of the phosphorus atom offers a large diversity of structures and as a consequence a wide range of properties for these materials. This study aims at taking profit of this easy functionalization to synthesize a series of degradable polymers of precisely tailored properties especially elasticity, hydrophilicity and functionality. We aim at developing a set of degradable materials in which only elasticity is varied keeping unchanged other parameters such as hydrophilicity, which remains quite a challenge. For that purpose, we have synthesized by organocatalyzed ring-opening polymerization,random di- and terpolymers between various cyclic phosphoesters bearing a short side-chain (hydrophilic), a longer side-chain (hydrophobic) and an unsaturated side-chain (butenyl)able to cross-link under UV irradiation. Playing on the composition of these copolymers, the cross-linking density and the hydrophilicity can be tuned quite independently. In the future, these materials will be used as model scaffolds to study the growth and differentiation of stem cells

Microscope-integrated optical coherence tomography: A new surgical tool in vitreoretinal surgery

Optical coherence tomography (OCT) has revolutionized imaging of ocular structures and various disease conditions. Though it has been used in the clinic for some decades, the OCT has only recently found its way into the operating theater. Early attempts at intraoperative OCT, hand-held and microscope mounted, have already improved our understanding of the surgical pathology and the role it might play in surgical decision-making. The microscope-integrated OCT now allows seamless, high-resolution, real-time imaging of surgical maneuvers from the incision to wound closure. Visualization of instruments and intraoperative tissue manipulation are possible with this in vivo modality and, therefore, help improve the outcome of surgery. In this article, we describe the advantages it offers during various vitreoretinal procedures

Design of degradable polyphosphoester networks with tailor-made stiffness and hydrophilicity as scaffolds for tissue engineering

In the recent decades, biodegradable and biocompatible polyphosphoesters (PPEs) have gained wide attention in the biomedical field as relevant substitutes for conventional aliphatic polyesters. These amorphous materials of low glass transition temperature offer promise for the design of soft scaffolds for tissue engineering. Advantageously, the easy variation of the nature of the lateral pendant groups of PPEs allows the insertion of pendent unsaturations valuable for their further cross- linking. In addition, varying the length of the pendent alkyl chains allows tuning their hydrophilicity. The present work aims at synthesizing PPE networks of well-defined hydrophilicity and mechanical properties. More precisely, we aimed at preparing degradable materials exhibiting identical hydrophilicity but different mechanical properties and vice versa. For that purpose, PPE copolymers were synthesized by ring-opening copolymerization of cyclic phosphate monomers bearing different pendent groups (e.g., methyl, butenyl, and butyl). After UV irradiation, a stable and well-defined cross-linked material is obtained with the mechanical property of the corresponding polymer films controlled by the composition of the starting PPE copolymer. The results demonstrate that cross-linking density could be correlated with the mechanical properties, swelling behavior, and degradation rate of the polymers network. The polymers were compatible to human skin fibroblast cells and did not exhibit significant cytotoxicity up to 0.5 mg mL−1. In addition, degradation products appeared nontoxic to skin fibroblast cells and showed their potential as promising scaffolds for tissue engineering.PAI program; Prostem projec

Prospective ARNI versus ACE inhibitor trial to DetermIne Superiority in reducing heart failure Events after Myocardial Infarction (PARADISE‐MI): design and baseline characteristics

Aims: Patients surviving an acute myocardial infarction (AMI) are at risk of developing symptomatic heart failure (HF) or premature death. We hypothesized that sacubitril/valsartan, effective in the treatment of chronic HF, prevents development of HF and reduces cardiovascular death following high-risk AMI compared to a proven angiotensin-converting enzyme (ACE) inhibitor. This paper describes the study design and baseline characteristics of patients enrolled in the Prospective ARNI vs. ACE inhibitor trial to DetermIne Superiority in reducing heart failure Events after Myocardial Infarction (PARADISE-MI) trial. Methods and results: PARADISE-MI, a multinational (41 countries), double-blind, active-controlled trial, randomized patients within 0.5–7 days of presentation with index AMI to sacubitril/valsartan or ramipril. Transient pulmonary congestion and/or left ventricular ejection fraction (LVEF) ≤40% and at least one additional factor augmenting risk of HF or death (age ≥70 years, estimated glomerular filtration rate <60 mL/min/1.73 m2, diabetes, prior myocardial infarction, atrial fibrillation, LVEF <30%, Killip class ≥III, ST-elevation myocardial infarction without reperfusion) were required for inclusion. PARADISE-MI was event-driven targeting 708 primary endpoints (cardiovascular death, HF hospitalization or outpatient development of HF). Randomization of 5669 patients occurred 4.3 ± 1.8 days from presentation with index AMI. The mean age was 64 ± 12 years, 24% were women. The majority (76%) qualified with ST-segment elevation myocardial infarction; acute percutaneous coronary intervention was performed in 88% and thrombolysis in 6%. LVEF was 37 ± 9% and 58% were in Killip class ≥II. Conclusions: Baseline therapies in PARADISE-MI reflect advances in contemporary evidence-based care. With enrollment complete PARADISE-MI is poised to determine whether sacubitril/valsartan is more effective than a proven ACE inhibitor in preventing development of HF and cardiovascular death following AMI

COVID-19 infected ST-Elevation myocardial infarction in India (COSTA INDIA)

Objective: To find out differences in the presentation, management and outcomes of COVID-19 infected STEMI patients compared to age and sex-matched non-infected STEMI patients treated during the same period. Methods: This was a retrospective multicentre observational registry in which we collected data of COVID-19 positive STEMI patients from selected tertiary care hospitals across India. For every COVID-19 positive STEMI patient, two age and sex-matched COVID-19 negative STEMI patients were enrolled as control. The primary endpoint was a composite of in-hospital mortality, re-infarction, heart failure, and stroke. Results: 410 COVID-19 positive STEMI cases were compared with 799 COVID-19 negative STEMI cases. The composite of death/reinfarction/stroke/heart failure was significantly higher among the COVID-19 positive STEMI patients compared with COVID-19 negative STEMI cases (27.1% vs 20.7% p value = 0.01); though mortality rate did not differ significantly (8.0% vs 5.8% p value = 0.13). Significantly lower proportion of COVID-19 positive STEMI patients received reperfusion treatment and primary PCI (60.7% vs 71.1% p value=< 0.001 and 15.4% vs 23.4% p value = 0.001 respectively). Rate of systematic early PCI (pharmaco-invasive treatment) was significantly lower in the COVID-19 positive group compared with COVID-19 negative group. There was no difference in the prevalence of high thrombus burden (14.5% and 12.0% p value = 0.55 among COVID-19 positive and negative patients respectively) Conclusions: In this large registry of STEMI patients, we did not find significant excess in in-hospital mortality among COVID-19 co-infected patients compared with non-infected patients despite lower rate of primary PCI and reperfusion treatment, though composite of in-hospital mortality, re-infarction, stroke and heart failure was higher

Exploring wheat landraces for rust resistance using a single marker scan

Marker-trait associations identified in diverse germplasm can be exploited in crop improvement programs. An attempt to establish such associations was made by evaluating 205 wheat landraces for stripe rust, leaf rust and stem rust responses in the field over three crop seasons. Diversity arrays technology was used to genotype the landraces and associations were identified using a single-marker scan. Sixty-eight markers were significantly associated with rust resistance. Several significantly associated loci coincided with the presence of known major genes or QTL for rust resistance. In contrast, many marker-rust response associations identified in this analysis for each of the three rust diseases uncovered new loci. Dual associations; stripe rust-leaf rust (1AL, 2BS, 2BL, 3DL, 5BS, 6BS and 7DL), leaf rust-stem rust (5BL) and stripe rust-stem rust (4BL and 6AS) resistance were also observed. These associations could enable a cost-effective targeted mapping of dual rust resistance. Some marker-trait associations identified in this study have been validated through genetic analyses and formal naming of resistance loci