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1.
Cureus ; 15(2): e34545, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36874346

RESUMEN

Background Melanoma is the most aggressive form of skin cancer, accounting for 3% of all malignant cancers. Phytochemicals and their related compounds are found in various parts of the plant Eichhornia crassipes and have a variety of pharmacological actions. The current research was intended to compare and evaluate the anti-proliferative action of methanolic extracts of E. crassipes roots and petioles against the Sloan Kettering Melanoma (SK-Mel-5) cell line. Materials and methods The waters around Ezhikkara, Ernakulum, Kerala, were discovered to contain E. crassipes. We used a Soxhlet extractor to get this concentrated liquid. For this test, we employed a methanolic extract of roots and petioles to determine the extent to which different concentrations of the extract inhibited cell proliferation. Data on absorbance were reported as a mean standard deviation. Using Probit analysis, the IC50 was calculated by evaluating the gradient of the regression line to get a value. Results Concentrations of methanolic root and petiole extracts of 12.5 µg/ml, 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml were analyzed. The methanol petiole extract reduced the viability of SK-Mel-5 cells more than the root extract, with IC50 values of 323.59 µg/ml and 174.70 µg/ml of the test sample concentration, respectively. The regression equation for the root extract was y = -0.1264x + 90.902 and R2 = 0.845, and for the petiole extract, it was y = -0.2187x + 88.206 and R2 = 0.917. Conclusion The current study found that increasing the concentration of methanolic extracts of roots and petioles of E. crassipes exhibited an increased cell growth inhibition rate. However, methanolic petiole extracts were more cytotoxic than the roots. Thus, the current study demonstrated the therapeutic use of E. crassipes as an anticancer agent, thereby providing a valuable alternative for enabling the early management of melanoma.

2.
Cureus ; 15(5): e38425, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37273397

RESUMEN

INTRODUCTION: Eichhornia crassipes (E. crassipes) are a longstanding hydrophyte belonging to the Pontederiaceae family and subfamily Trollioideae. It is classified as an invasive plant owing to its phenomenal growth and propagation and is often described as the worst aquatic plant. Natural antioxidants, such as phenolic compounds and flavonoids, have an increased protective effect against free radicals. A single laboratory test is insufficient to comprehend all of the mechanisms entailed in investigating the antioxidant effects of the phytoconstituents. The antioxidant propensity of methanolic extracts from E. crassipes petioles was investigated in this study utilizing 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-pycryl-hydrazyl (DPPH). Additionally, the cytotoxic effect of E. crassipes methanolic petiole extract upon MG-63 cell lines for the inhibition of osteosarcoma cells was investigated. MATERIALS AND METHODS:  The antioxidant propensity was appraised by employing DPPH and ABTS assays. The cytotoxic effects of the methanolic petiole extract of E. crassipes at varying concentrations on MG-63 cell lines were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. The absorbance scores were computed using the mean and standard deviation. The half-maximal inhibitory concentration (IC50) was calculated by applying probit analysis. The data were analyzed using SPSS Statistics for the descriptive statistics of the percentage of cell viability and regression analysis. RESULTS: The antioxidant potential was assessed by employing DPPH and ABTS assays at various concentration levels of 50 µg/ml, 100 µg/ml, 200 µg/ml, and 400 µg/ml of methanolic petiole extracts. The antioxidant potential of DPPH (57.95%) and ABTS (60.47%) was more at the elevated doses of 400 µg/mL. The percentage of cell viability upon MG-63 cell line was measured at varying doses of 12.5 µg/ml, 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml of methanolic petiole extracts and was found to be 99.36%, 93.92%, 86.77%, 69.14%, and 45.08%, respectively. The IC50 value for the extract of E. crassipes against the MG-63 cell line was 177.65 µg/mL. The regression equation computed from the findings of the probit analysis was y = -0.2881x + 101.18 with a coefficient of determination of R² = 0.992. CONCLUSION: The methanolic extracts of the various parts of the plant, such as leaves, flower, rhizome, and petioles, have been established in similar prior studies to contain the highest phenolic constituents and were found to have a high rate of DPPH radical scavenging activity and reducing power. It is inferred from the findings of the present study that E. crassipes petiole extracts have a significant protective role against oxidative stress, potentially attributed to the antioxidant potential. Further, the findings of the study reveal that the methanolic petiole extract of E. crassipes induced cytotoxicity upon MG-63 cell lines with an IC50 value of 177.65 µg/mL.

3.
Cureus ; 14(10): e30554, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-36415425

RESUMEN

Background Eichhornia crassipes (E. crassipes) have several secondary metabolites that have medicinal value. These include sterols, alkaloids, phenolics, flavonoids, tannins, and saponins. In the current study, the methanolic petiole extract of E. crassipes was examined to determine its potential antiproliferative activity against Sloan Kettering Melanoma 5 (SK-Mel-5) cell lines. Materials and methods Eichhornia crassipes were obtained from the water bodies of Ezhikkara, Ernakulam, Kerala. The Soxhlet technique was used to produce the extract. Leaves, petioles, and roots were dried and pulverized before being analyzed phytochemically in a number of solvents. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to measure the extent to which various dosages of the extract inhibited cell proliferation, and the methanolic extract of petioles was chosen since it contained more anticancer components. The half maximal inhibitory concentration (IC50) was determined by utilizing a probit model and the slope-gradient method of the regression equation. The Statistical Package for Social Sciences (SPSS) version 21 (IBM SPSS Statistics, Armonk, NY) was used for the analysis. Results We examined the effects of 12.5, 25, 50, 100, and 200 µg/ml of methanolic petiole extract. The data indicated that the methanol extract significantly reduced SK-Mel-5 cell viability. Cell growth inhibition increased with concentration but was shown to be relatively low at 100 g/ml, exhibiting 38.911% of inhibitory activity. The percentage of cell growth inhibition at 200 g/ml was 52.965%. The methanolic petiole extracts of E. crassipes were found to be cytotoxic with IC50 values of 172.186 g/ml. Probit analysis was performed to obtain the regression equation. Conclusion The in vitro study suggests that the methanol extract of the petiole of E. crassipes had modest antiproliferative action against SK-Mel-5 cells, a typical human melanocyte tumor cell line. The study findings shed light on the anticancer activity of E. crassipes, making it an appropriate source of drug-lead chemicals for the development of safer and cost-effective remedies for cutaneous ailments varying from rashes to awful melanoma.

4.
Cureus ; 14(12): e32616, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36660523

RESUMEN

BACKGROUND: An increasing number of people are turning to herbal medicines in their search for innovative pharmaceuticals since they are effective treatments for a wide variety of conditions and traditional herbs are rich in bioactive chemicals. In this study, we looked at whether or not a petiole extract of Eichhornia crassipes preserved in methanol inhibited the proliferation of prostate cancer (PC3) cell lines. MATERIALS AND METHODS: Lakes in Ezhikkara, Ernakulum, Kerala, were the source of E. crassipes. Soxhlet extraction was used to create the extract. 3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the cell viability of methanolic petiole extract at various concentrations. Mean and standard deviation was used to determine absorbance scores. Utilizing probit analysis, we determined the IC50 value. The descriptive statistics to measure the percent of viable cells along with the regression equation were calculated using SPSS. RESULTS: It has been shown that the methanol extract significantly impacted PC3 cell lines' capacity to survive. It was also determined that increasing the medication concentration resulted in a decrease in cell viability. The percentage of living cells was measured after being exposed to methanol extracts at concentrations of 12.5 µg/ml, 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml, and found to be 95.13, 85.88, 76.12, 64.33, and 53.62 percent, respectively. With IC50 values of 199.488 g/ml, it was shown that methanolic petiole extracts of E. crassipes are cytotoxic. Using probit analysis, we determined that the regression equation is y = -0.2051x + 90.915, with an R2 value of 0.893. CONCLUSION: As a result of its chemotherapeutic properties, the E. crassipes petiole extract has the potential to be employed in therapeutic applications, with the ultimate goal of bettering prostate cancer management practices and clinical results by drastically lowering cell viability. The study's results may pave the way for fresh chemotherapeutic approaches to be developed for the treatment of androgen-independent prostate cancer.

5.
Heart Views ; 23(3): 138-143, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36479176

RESUMEN

Aim: The purpose of this study is to assess the effect of the COVID-19 pandemic on the volume of ST-elevation myocardial infarction (STEMI) patients and also to assess changes in patient characteristics, door-in-to-door-out (DIDO) time, door-to-balloon time (D2B) time, and STEMI outcomes during the pandemic. Methods: Patient data were retrieved retrospectively from the electronic medical record system of King Hamad University Hospital and Mohammed Bin Khalifa Cardiac Centre in the Kingdom of Bahrain. Data were compared and analyzed for the two time periods: before the pandemic (January 2019-March 2020) and during the pandemic (April 2020June 2021). Results: There was a decline of 11.1% in patients who presented with STEMI during the pandemic. There were no major differences between the patient demographics and the baseline characteristics during the two study periods. Recommended DIDO time and D2B time could be achieved only for 7.1% and 35.7% of all STEMI cases during the pandemic. However, no significant differences were noted in the 30 days of mortality, reinfarction, cardiogenic shock, hospital length of stay, and return to the hospital within 30 days for the STEMI patients in the two time periods. Conclusions: There was a decline in patients who presented with STEMI during the pandemic. This was also associated with a lower number of STEMI cases achieving the recommended DIDO time and D2B time as compared to the prepandemic period. However, there was no significant difference in the patient outcomes in the two time periods.

6.
J Am Coll Radiol ; 19(5): 637-646, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35346619

RESUMEN

PURPOSE: The aim of this study was to scale structured report templates categorizing actionable renal findings across health systems and create a centralized registry of patient and report data. METHODS: In January 2017, three academic radiology departments agreed to prospectively include identical structured templates categorizing the malignant likelihood of renal findings in ≥90% of all adult ultrasound, MRI, and CT reports, a new approach for two sites. Between November 20, 2017, and September 30, 2019, deidentified HL7 report data were transmitted to a centralized ACR registry. An automated algorithm extracted categories. Radiologists were requested to addend reports with missing or incomplete templates after the first month. Separately, each site submitted patient sociodemographic and clinical data 12 months before and at least 3 months after enrollment. RESULTS: A total of 164,982 eligible radiology reports were transmitted to the registry; 4,159 (2.5%) were excluded because of missing categories or radiologist names. The final cohort included 160,823 examinations on 102,619 unique patients. Mean template use before and after addendum requests was 99.3% and 99.9% at SITE1, 86.5% and 94.6% at SITE2, and 91.4% and 96.0% at SITE3. Matching patient sociodemographic and clinical data were obtained on 96.9% of reports from SITE1, 94.2% from SITE2, and 96.0% from SITE3. Regulatory, cultural, and technology barriers to the creation of a multisite registry were identified. CONCLUSIONS: Barriers to the adoption of unified structured report templates for actionable kidney findings can be addressed. Deidentified report and patient data can be securely transmitted to an external registry. These data can facilitate the collection of diverse evidence-based population imaging outcomes.


Asunto(s)
Servicio de Radiología en Hospital , Sistemas de Información Radiológica , Adulto , Humanos , Riñón , Imagen por Resonancia Magnética , Sistema de Registros
7.
JAMIA Open ; 5(4): ooac094, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36380846

RESUMEN

Objective: To develop a free, vendor-neutral software suite, the American College of Radiology (ACR) Connect, which serves as a platform for democratizing artificial intelligence (AI) for all individuals and institutions. Materials and Methods: Among its core capabilities, ACR Connect provides educational resources; tools for dataset annotation; model building and evaluation; and an interface for collaboration and federated learning across institutions without the need to move data off hospital premises. Results: The AI-LAB application within ACR Connect allows users to investigate AI models using their own local data while maintaining data security. The software enables non-technical users to participate in the evaluation and training of AI models as part of a larger, collaborative network. Discussion: Advancements in AI have transformed automated quantitative analysis for medical imaging. Despite the significant progress in research, AI is currently underutilized in current clinical workflows. The success of AI model development depends critically on the synergy between physicians who can drive clinical direction, data scientists who can design effective algorithms, and the availability of high-quality datasets. ACR Connect and AI-LAB provide a way to perform external validation as well as collaborative, distributed training. Conclusion: In order to create a collaborative AI ecosystem across clinical and technical domains, the ACR developed a platform that enables non-technical users to participate in education and model development.

8.
JAMIA Open ; 4(4): ooab106, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34927003

RESUMEN

OBJECTIVE: Clinical Knowledge Authoring Tools (CKATs) are integral to the computerized Clinical Decision Support (CDS) development life cycle. CKATs enable authors to generate accurate, complete, and reliable digital knowledge artifacts in a relatively efficient and affordable manner. This scoping review aims to compare knowledge authoring tools and derive the common features of CKATs. MATERIALS AND METHODS: We performed a keyword-based literature search, followed by a snowball search, to identify peer-reviewed publications describing the development or use of CKATs. We used PubMed and Embase search engines to perform the initial search (n = 1579). After removing duplicate articles, nonrelevant manuscripts, and not peer-reviewed publication, we identified 47 eligible studies describing 33 unique CKATs. The reviewed CKATs were further assessed, and salient characteristics were extracted and grouped as common CKAT features. RESULTS: Among the identified CKATs, 55% use an open source platform, 70% provide an application programming interface for CDS system integration, and 79% provide features to validate/test the knowledge. The majority of the reviewed CKATs describe the flow of information, offer a graphical user interface for knowledge authors, and provide intellisense coding features (94%, 97%, and 97%, respectively). The composed list of criteria for CKAT included topics such as simulating the clinical setting, validating the knowledge, standardized clinical models and vocabulary, and domain independence. None of the reviewed CKATs met all common criteria. CONCLUSION: Our scoping review highlights the key specifications for a CKAT. The CKAT specification proposed in this review can guide CDS authors in developing more targeted CKATs.

9.
J Am Coll Radiol ; 18(12): 1605-1613, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34419476

RESUMEN

OBJECTIVES: The aim of this study was to compare how often fine-needle aspiration (FNA) would be recommended for nodules in unselected, low-risk adult patients referred for sonographic evaluation of thyroid nodules by ACR Thyroid Imaging Reporting and Data System (TI-RADS), the American Thyroid Association guidelines (ATA), Korean Thyroid Imaging Reporting and Data System (K-TIRADS), European Thyroid Imaging Reporting and Data System (EU-TIRADS), and Artificial Intelligence Thyroid Imaging Reporting and Data System (AI-TIRADS). METHODS: Seven practices prospectively submitted thyroid ultrasound reports on adult patients to the ACR Thyroid Imaging Research Registry between October 2018 and March 2020. Data were collected about the sonographic features of each nodule using a structured reporting template with fields for the five ACR TI-RADS ultrasound categories plus maximum nodule size. The nodules were also retrospectively categorized according to criteria from ACR TI-RADS, the ATA, K-TIRADS, EU-TIRADS, and AI-TIRADS to compare FNA recommendation rates. RESULTS: For 27,933 nodules in 12,208 patients, ACR TI-RADS recommended FNA for 8,128 nodules (29.1%, 95% confidence interval [CI] 0.286-0.296). The ATA guidelines, EU-TIRADS, K-TIRADS, and AI-TIRADS would have recommended FNA for 16,385 (58.7%, 95% CI 0.581-0.592), 10,854 (38.9%, 95% CI 0.383-0.394), 15,917 (57.0%, 95% CI 0.564-0.576), and 7,342 (26.3%, 95% CI 0.258-0.268) nodules, respectively. Recommendation for FNA on TR3 and TR4 nodules was lowest for ACR TI-RADS at 18% and 30%, respectively. ACR TI-RADS categorized more nodules as TR2, which does not require FNA. At the high suspicion level, the FNA rate was similar for all guidelines at 68.7% to 75.5%. CONCLUSION: ACR TI-RADS recommends 25% to 50% fewer biopsies compared with ATA, EU-TIRADS, and K-TIRADS because of differences in size thresholds and criteria for risk levels.


Asunto(s)
Neoplasias de la Tiroides , Nódulo Tiroideo , Adulto , Inteligencia Artificial , Biopsia con Aguja Fina , Humanos , Sistema de Registros , Estudios Retrospectivos , Glándula Tiroides/diagnóstico por imagen , Nódulo Tiroideo/diagnóstico por imagen , Ultrasonografía
10.
Proteomics ; 9(7): 1893-900, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19288524

RESUMEN

A stable and robust trypsin-based biocatalytic system was developed and demonstrated for proteomic applications. The system utilizes polymer nanofibers coated with trypsin aggregates for immobilized protease digestions. After covalently attaching an initial layer of trypsin to the polymer nanofibers, highly concentrated trypsin molecules are crosslinked to the layered trypsin by way of a glutaraldehyde treatment. This process produced a 300-fold increase in trypsin activity compared with a conventional method for covalent trypsin immobilization, and proved to be robust in that it still maintained a high level of activity after a year of repeated recycling. This highly stable form of immobilized trypsin was resistant to autolysis, enabling repeated digestions of BSA over 40 days and successful peptide identification by LC-MS/MS. This active and stable form of immobilized trypsin was successfully employed in the digestion of yeast proteome extract with high reproducibility and within shorter time than conventional protein digestion using solution phase trypsin. Finally, the immobilized trypsin was resistant to proteolysis when exposed to other enzymes (i.e., chymotrypsin), which makes it suitable for use in "real-world" proteomic applications. Overall, the biocatalytic nanofibers with trypsin aggregate coatings proved to be an effective approach for repeated and automated protein digestion in proteomic analyses.


Asunto(s)
Reactores Biológicos , Enzimas Inmovilizadas/metabolismo , Nanoestructuras , Polímeros/metabolismo , Tripsina/metabolismo , Biocatálisis , Cromatografía Liquida , Estabilidad de Enzimas , Equipo Reutilizado , Microscopía Electrónica de Rastreo , Nanoestructuras/ultraestructura , Fragmentos de Péptidos , Proteínas/metabolismo , Proteómica/instrumentación , Reproducibilidad de los Resultados , Espectrometría de Masas en Tándem
11.
J Am Coll Radiol ; 14(9): 1184-1189, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28648871

RESUMEN

Decreasing unnecessary variation in radiology reporting and producing guideline-concordant reports is fundamental to radiology's success in value-based payment models and good for patient care. In this article, we present an open authoring system for point-of-care clinical decision support tools integrated into the radiologist reporting environment referred to as the computer-assisted reporting and decision support (CAR/DS) framework. The CAR/DS authoring system, described herein, includes: (1) a definition format for representing radiology clinical guidelines as structured, machine-readable Extensible Markup Language documents and (2) a user-friendly reference implementation to test the fidelity of the created definition files with the clinical guideline. The proposed definition format and reference implementation will enable content creators to develop CAR/DS tools that voice recognition software (VRS) vendors can use to extend the commercial tools currently in use. In making the definition format and reference implementation software freely available, we hope to empower individual radiologists, expert groups such as the ACR, and VRS vendors to develop a robust ecosystem of CAR/DS tools that can further improve the quality and efficiency of the patient care that our field provides. We hope that this initial effort can serve as the basis for a community-owned open standard for guideline definition that the imaging informatics and VRS vendor communities will embrace and strengthen. To this end, the ACR Assist™ initiative is intended to make the College's clinical content, including the Incidental Findings Committee White Papers, available for decision support tool creation based upon the herein described CAR/DS framework.


Asunto(s)
Sistemas de Apoyo a Decisiones Clínicas/organización & administración , Adhesión a Directriz , Sistemas de Atención de Punto/organización & administración , Radiólogos , Humanos , Programas Informáticos
12.
J Phys Chem B ; 109(25): 12491-7, 2005 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-16852544

RESUMEN

Polyethylene nanofibers were synthesized by heterogeneous Ziegler-Natta polymerization inside nanochannels of robust anodized aluminum oxide (AAO) membranes. The polymerization catalysts were chemisorbed at the inner wall of the nanochannels and monomers were provided through diffusion from the outside. Polyethylene is produced inside the nanochannels in the 10-20 mum region from the channel entrance. Polyethylene fibers were extruded from the nanochannels up to 3-5 mum during the polymerization. X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analyses indicated formation of a highly stressed crystalline structure although the polymerization was carried out without any external pressure or mechanical work. The highly stressed phase formation inside nanochannels and some degree of polyethylene nanofiber extrusion from nanochannels were attributed to catalytic production of excess amounts of polyethylene inside nanoconfined templates.

13.
Curr Drug Deliv ; 12(5): 517-23, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25675336

RESUMEN

Mortality rate due to heart diseases increases dramatically with age. Captopril is an angiotensin converting enzyme inhibitor (ACE) used effectively for the management of hypertension. Due to short elimination half-life of captopril the oral dose is very high. Captopril is prone to oxidation and it has been reported that the oxidation rate of captopril in skin tissues is considerably low when compared to intestinal tissues. All these factors make captopril an ideal drug candidate for transdermal delivery. In this research work an effort was made to formulate transdermal films of captopril by utilizing polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) as film formers and polyethylene glycol 400 (PEG400) as a plasticizer. Dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) were used as permeation enhancers. Physicochemical parameters of the films such as appearance, thickness, weight variation and drug content were evaluated. The invitro permeation studies were carried out through excised human cadaver skin using Franz diffusion cells. The in-vitro permeation studies demonstrated that the film (P4) having the polymer ratio (PVP:PVA = 80:20) with DMSO (10%) resulted a promising drug release of 79.58% at 24 hours with a flux of 70.0 µg/cm(2)/hr. No signs of erythema or oedema were observed on the rabbit skin as a result of skin irritation study by Draize test. Based on the stability report it was confirmed that the films were physically and chemically stable, hence the prepared films are very well suited for transdermal application.


Asunto(s)
Captopril/administración & dosificación , Captopril/farmacocinética , Absorción Cutánea , Piel/metabolismo , Parche Transdérmico , Administración Cutánea , Animales , Cadáver , Dimetilsulfóxido/química , Dimetilsulfóxido/farmacología , Dimetilformamida/química , Dimetilformamida/farmacología , Humanos , Oxidación-Reducción , Permeabilidad/efectos de los fármacos , Polietilenglicoles/química , Alcohol Polivinílico/química , Povidona/química , Conejos , Piel/efectos de los fármacos , Absorción Cutánea/efectos de los fármacos
14.
Biosens Bioelectron ; 26(5): 1980-6, 2011 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-20951568

RESUMEN

This paper describes highly stable enzyme precipitate coatings (EPCs) on electrospun polymer nanofibers and carbon nanotubes (CNTs), and their potential applications in the development of highly sensitive biosensors and high-powered biofuel cells. EPCs of glucose oxidase (GOx) were prepared by precipitating GOx molecules in the presence of ammonium sulfate, then cross-linking the precipitated GOx aggregates on covalently attached enzyme molecules on the surface of nanomaterials. EPCs-GOx not only improved enzyme loading, but also retained high enzyme stability. For example, EPC-GOx on CNTs showed a 50 times higher activity per unit weight of CNTs than the conventional approach of covalent attachment, and its initial activity was maintained with negligible loss for 200 days. EPC-GOx on CNTs was entrapped by Nafion to prepare enzyme electrodes for glucose sensors and biofuel cells. The EPC-GOx electrode showed a higher sensitivity and a lower detection limit than an electrode prepared with covalently attached GOx (CA-GOx). The CA-GOx electrode showed an 80% drop in sensitivity after thermal treatment at 50°C for 4 h, while the EPC-GOx electrode maintained its high sensitivity with negligible decrease under the same conditions. The use of EPC-GOx as the anode of a biofuel cell improved the power density, which was also stable even after thermal treatment of the enzyme anode at 50°C. The excellent stability of the EPC-GOx electrode together with its high current output create new potential for the practical applications of enzyme-based glucose sensors and biofuel cells.


Asunto(s)
Técnicas Biosensibles/instrumentación , Conductometría/instrumentación , Electrodos , Glucosa Oxidasa/química , Glucosa/análisis , Precipitación Química , Estabilidad de Enzimas , Enzimas Inmovilizadas/química , Diseño de Equipo , Análisis de Falla de Equipo , Glucosa/química
15.
Biomacromolecules ; 8(4): 1266-70, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17305393

RESUMEN

A simple and efficient way of dispersing hydrophobic nanofibers in aqueous solution was devised, and its utility in production and application of enzyme-loaded nanofibers was demonstrated. Polystyrene-based nanofibers were produced via an electro-spinning process. A small amount of maleic anhydride group in the polystyrene fiber was used for covalent attachment of lipase onto the fiber surface. The pristine polystyrene nanofibers are hydrophobic and aggregate in water, forming a tightly collapsed clump. These nanofibers can be dispersed in a surfactant-free aqueous solution via a simple alcohol pretreatment. The tightly aggregated electro-spun polystyrene nanofibers can be dispersed into a loosely entangled structure in aqueous alcohol solution. Once treated with aqueous alcohol solution, the polystyrene nanofibers remain dispersed even in DI water as long as the nanofibers are not dried during the washing step. The dispersion of polystyrene nanofibers increases the enzyme loading up to approximately 8 times and augments the steady-state conversion of a continuous flow reactor filled with enzyme-loaded nanofibers.


Asunto(s)
Lipasa/química , Nanoestructuras , Poliestirenos/química , Catálisis , Interacciones Hidrofóbicas e Hidrofílicas , Estructura Molecular , Nanoestructuras/química , Nanoestructuras/ultraestructura , Tamaño de la Partícula , Propiedades de Superficie
16.
Nanotechnology ; 16(7): S382-8, 2005 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21727456

RESUMEN

We have developed a unique approach for the fabrication of enzyme aggregate coatings on the surfaces of electrospun polymer nanofibres. This approach employs covalent attachment of seed enzymes onto nanofibres consisting of a mixture of polystyrene and poly(styrene-co-maleic anhydride), followed by a glutaraldehyde (GA) treatment that cross-links additional enzyme molecules and aggregates from the solution onto the covalently attached seed enzyme molecules. These cross-linked enzyme aggregates, covalently attached to the nanofibres via the linkers of seed enzyme molecules, are expected to improve the enzyme activity due to increased enzyme loading, and also the enzyme stability. To demonstrate the principle, we coated α-chymotrypsin (CT) on nanofibres electrospun from a mixture of polystyrene and poly(styrene-co-maleic anhydride). The initial activity of CT-aggregate-coated nanofibres was nine times higher than nanofibres with just a layer of covalently attached CT molecules. The enzyme stability of CT-aggregate-coated nanofibres was greatly improved with essentially no measurable loss of activity over a month of observation under rigorous shaking conditions. This new approach of enzyme coating on nanofibres, yielding high activity and stability, creates a useful new biocatalytic immobilized enzyme system with potential applications in bioconversion, bioremediation, and biosensors.

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