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1.
Pak J Med Sci ; 39(5): 1488-1491, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37680808

RESUMEN

Objectives: To determine the change in macular thickness after uncomplicated phacoemulsification surgery using optical coherence tomography in a tertiary care hospital. Methods: This study was conducted at Department of Ophthalmology Jinnah Postgraduate Medical Centre Karachi, for 6 months from 10th Dec 2019 to 10th June 2020. Sample size calculation of 52 eyes was done by using open epi software. Patients who fulfilled the inclusion criteria that is age ranging from 50 to 75 years, either gender with senile cataract having no preexisting ocular or systemic disease and those giving consent were included in this study. Patients with any comorbidity ocular trauma, having pre-existing ocular diseases such as active ocular infection, glaucoma, maculopathy or retinopathy were excluded from study. Patients with secondary cataract also excluded from study. After complete history, all patients underwent detailed ophthalmologic examination and Pre-surgery macular thickness recorded by using swept source OCT (DRI-OCT-2 Triton; Topcon). Surgery was performed and intraocular lens was implanted in all cases. Post procedure Macular thickness was measured using swept source OCT at 1st postoperative day, 1st month and 6th month after surgery. Results: The mean age of patients was 62.06 ± 5.1 years. Total of 52 eyes diagnosed with senile cataract were included in this study. There were 30 (57.7%) males and 22(42.3%) females. The mean preoperative central foveal thickness was 201.3±24.8µm. The postoperative central foveal thickness was 200.3±25.2µm (153-265µm) at day 1st of surgery, 224.1 ± 53.8 µm (151-458 µm) at 1st month and 212.4±28.3µm (167-255µm) 6th month after surgery. The mean preoperative BCVA was 0.70 ± 0.43 (0.1-1.7) logMAR. The postoperative mean BCVA was 0.26 ± 0.42 (0.00-3.10) logMAR at 1st day, 0.07± 0.10 (0.000.7) logMAR at 1st month and 0.05 ± 0.10 (0.00-0.3) logMAR at 6th month. Conclusion: In our study we found an increase in macular thickness but there was no loss of BCVA from changes of macular thickness after surgery and the mean BCVA increased progressively in postoperative period.

2.
Pak J Med Sci ; 38(1): 254-260, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35035435

RESUMEN

OBJECTIVES: To compare the choroidal thickness in eyes of diabetic patients with eyes of age matched controls using optical coherence tomography in a tertiary care hospital. METHODS: This Cross sectional study was conducted at the Department of Ophthalmology, Jinnah Postgraduate Medical Centre Karachi, for six months from13thJanuary 2020 to13thJuly 2020. The study group comprised of 44 patients with 88 eyes. Patients who fulfill the inclusion criteria that is age ranging from 35 to 80years, either gender, known case of diabetes mellitus and having any type of diabetic retinopathy (HbA1c >7), non-diabetic healthy individuals (HbA1c < 7) and those giving informed consent were included in the study. However, patients having active ocular infections, history of myocardial infarction, stroke, uveitis, any ocular surgery, lasers, intravitreal injections, poor fundus view and not giving consent were excluded. A pre-designed proforma was filled. A baseline ocular examination was performed and choroidal thickness was assessed from retinal pigment epithelium to choroid sclera junction in diabetic and healthy participants of the study group using high resolution Swept source OCT (DRI-OCT-2 Triton; Topcon). RESULTS: The average age of the patients was 39.41±15.95 years. According to our study mean central subfoveal choroidal thickness in diabetic eyes was 268.5 ± 66.22 (95% CI 240 - 297) and in non-diabetic healthy participants it was 339.3 ± 71.49 (95% CI 308 - 369) with a p-value of 0.001. However, average choroidal thickness was 261.8 ± 61.93 (95% CI 235 - 288) and 336.0 ± 74.35 (95% CI 304 - 367) in diabetic and non-diabetic healthy population with a p-value of 0.001. Choroidal thickness comparison between gender in diabetic and non-diabetic population also showed similar trend. CONCLUSION: In this study, mean central choroidal thickness as well as average choroidal thickness was significantly reduced in eyes having diabetic retinopathy as compared to participants with non-diabetic healthy eyes. These findings indicate that changes in choroid may be a probable route in the pathogenesis of diabetic retinopathy.

3.
J Environ Sci (China) ; 100: 11-17, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33279023

RESUMEN

Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy (SERS) substrates to test the individual atmospheric aerosols particle. Compared to other methods used for testing atmospheric aerosols particles, the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte. The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings. The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate, which can improve the accuracy for detecting atmospheric aerosol particles. Combined with Raman mapping, the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually. The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition, mixing state, and other related physicochemical properties.


Asunto(s)
Nanopartículas del Metal , Espectrometría Raman , Aerosoles , Oro
4.
Environ Sci Technol ; 54(24): 15594-15603, 2020 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-33095569

RESUMEN

Micro- and nanoplastics are considered one of the top pollutants that threaten the environment, aquatic life, and mammalian (including human) health. Unfortunately, the development of uncomplicated but reliable analytical methods that are sensitive to individual microplastic particles, with sizes smaller than 1 µm, remains incomplete. Here, we demonstrate the detection and identification of (single) micro- and nanoplastics by using surface-enhanced Raman spectroscopy (SERS) with Klarite substrates. Klarite is an exceptional SERS substrate; it is shaped as a dense grid of inverted pyramidal cavities made of gold. Numerical simulations demonstrate that these cavities (or pits) strongly focus incident light into intense hotspots. We show that Klarite has the potential to facilitate the detection and identification of synthesized and atmospheric/aquatic microplastic (single) particles, with sizes down to 360 nm. We find enhancement factors of up to 2 orders of magnitude for polystyrene analytes. In addition, we detect and identify microplastics with sizes down to 450 nm on Klarite, with samples extracted from ambient, airborne particles. Moreover, we demonstrate Raman mapping as a fast detection technique for submicron microplastic particles. The results show that SERS with Klarite is a facile technique that has the potential to detect and systematically measure nanoplastics in the environment. This research is an important step toward detecting nanoscale plastic particles that may cause toxic effects to mammalian and aquatic life when present in high concentrations.


Asunto(s)
Microplásticos , Contaminantes Químicos del Agua , Oro , Humanos , Plásticos , Poliestirenos , Espectrometría Raman , Contaminantes Químicos del Agua/análisis
5.
Sensors (Basel) ; 20(8)2020 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-32325814

RESUMEN

The advent of new devices, technology, machine learning techniques, and the availability of free large speech corpora results in rapid and accurate speech recognition. In the last two decades, extensive research has been initiated by researchers and different organizations to experiment with new techniques and their applications in speech processing systems. There are several speech command based applications in the area of robotics, IoT, ubiquitous computing, and different human-computer interfaces. Various researchers have worked on enhancing the efficiency of speech command based systems and used the speech command dataset. However, none of them catered to noise in the same. Noise is one of the major challenges in any speech recognition system, as real-time noise is a very versatile and unavoidable factor that affects the performance of speech recognition systems, particularly those that have not learned the noise efficiently. We thoroughly analyse the latest trends in speech recognition and evaluate the speech command dataset on different machine learning based and deep learning based techniques. A novel technique is proposed for noise robustness by augmenting noise in training data. Our proposed technique is tested on clean and noisy data along with locally generated data and achieves much better results than existing state-of-the-art techniques, thus setting a new benchmark.


Asunto(s)
Ruido , Software de Reconocimiento del Habla , Aprendizaje Profundo , Humanos , Aprendizaje Automático , Redes Neurales de la Computación , Percepción del Habla/fisiología
6.
Anal Chem ; 91(21): 13647-13657, 2019 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-31580648

RESUMEN

Surface enhanced Raman spectroscopy (SERS) shows great promise in studying individual atmospheric aerosol. However, the lack of efficient, stable, uniform, large-array, and low-cost SERS substrates constitutes a major roadblock. Herein, a new SERS substrate is proposed for detecting individual atmospheric aerosol particles. It is based on the sphere segment void (SSV) structure of copper and silver (Cu/Ag) alloy. The SSV structure is prepared by an electrodeposition method and presents a uniform distribution, over large 2 cm2 arrays and at low cost. The substrate offers a high SERS enhancement factor (due to Ag) combined with lasting stability (due to Cu). The SSV structure of the arrays generates a high density of SERS hotspots (1.3 × 1014/cm2), making it an excellent substrate for atmospheric aerosol detection. For stimulated sulfate aerosols, the Raman signal is greatly enhanced (>50 times), an order of magnitude more than previously reported substrates for the same purpose. For ambient particles, collected and studied on a heavy haze day, the enhanced Raman signal allows ready observation of morphology and identification of chemical components, such as nitrates and sulfates. This work provides an efficient strategy for developing SERS substrate for detecting individual atmospheric aerosol.

7.
Analyst ; 145(1): 277-285, 2019 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-31746822

RESUMEN

Detecting atmospheric bioaerosols in a quantitative way is highly desirable for public health and safety. This work demonstrates that surface-enhanced Raman spectroscopy (SERS) is a simple and rapid analytical technique for the detection of atmospheric bioaerosols, on a Klarite substrate. For both simulated and ambient bioaerosols, this detection assay results in an increase in the enhancement factor of the Raman signal. We report a strong SERS signal generated by bioaerosols containing living Escherichia coli deposited on Klarite. Furthermore, we demonstrate that SERS mapping can be used to estimate the percentage of airborne, living Escherichia coli. Moreover, Klarite provides differently distinct SERS spectra at different bacterial growth phases, indicating its potential to identify changes occurring in the bacterial envelope. Finally, we applied SERS for the rapid detection of Escherichia coli in ambient bioaerosols without using time-consuming and laborious culture processes. Our results represent rapid, culture-free and label-free detection of airborne bacteria in the real-world environment.


Asunto(s)
Aerosoles/análisis , Técnicas Bacteriológicas/métodos , Escherichia coli/aislamiento & purificación , Nanopartículas del Metal/química , Espectrometría Raman/métodos , Escherichia coli/clasificación , Oro/química , Viabilidad Microbiana , Silicio/química
8.
Pak J Med Sci ; 34(1): 221-225, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29643911

RESUMEN

OBJECTIVE: To compare the success in patients having vitreous hemorrhage undergoing pars plana vitrectomy with or without preoperative intravitreal injection of Bevacizumab. METHODS: This Randomized controlled trial was conducted at Department of Ophthalmology, Jinnah Postgraduate Medical Centre. Karachi. Duration of study was six months from January 2010 to June 2010. In this study 56 patients of advanced diabetic eye disease were divided into two groups. Patients in Group-A underwent three ports pars plana vitrectomy with preoperative intravitreal injection of Bevacizumab (Avastin) 1.25mg/0.05ml, 3.5mm from the limbus seven days before surgery and in Group-B patients underwent vitrectomy without preoperative intravitreal Bevacizumab (Avastin). Intraoperative bleeding was monitored in both groups and was graded as no bleeding, mild bleeding and severe bleeding. The results were statistically analyzed through computer software SPSS 17. RESULTS: Twenty eight patients in Group-A who were given an injection of intravitreal Bevacizumab (Avastin) before surgery, intraoperative bleeding monitored was, no bleeding in 17 cases (60.7%), mild was observed in 6 cases (21.4%) and severe bleeding requiring diathermy to stop was observed in only 5 cases (17.9%). 28 patients in Group-B that underwent surgery without Avastin no bleeding was observed in only 2 cases (7.1%), mild in 6 cases (21.4%) and severe in 20 cases (71.4%). CONCLUSIONS: Intravitreal injection of Bevacizumab (Avastin) was effective before vitrectomy in the surgical management of Advanced Diabetic Eye disease.

9.
Pak J Med Sci ; 33(5): 1171-1176, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29142559

RESUMEN

OBJECTIVE: To assess visual and anatomical outcome of full thickness macular hole (FTMH) surgery with ILM peeling using brilliant blue G dye. METHODS: Thirty patients who had clinically evident macular hole were selected. Pre-operative Optical Coherence Tomography (OCT) was done. In all cases vitrectomy was performed via 23guage 3 ports pars plana (3PPV) vitrectomy system and Brilliant blue G dye, 0.5ml dye was injected over macula which resulted in light blue stain of ILM and peeling was performed around hole in circular motion and after gas fluid exchange gas tamponade with SF6 was done. Final visual and anatomical outcome was measured as postoperative BCVA and postoperative OCT at three months respectively. Descriptive statistics were computed. Paired t-test was applied. P value≤0.05 were considered as significant. RESULTS: There were 12 male and 18 female patients. The mean age was 57.40±4.76 years. The mean size of macular hole was 452.20±242.33µm. The mean duration of symptoms was 16.73±13.49 weeks. Mean pre operative BCVA was 1.30±0.73 log MAR and post operative was 0.51±0.23 log MAR. Mean increased BCVA was found to be 0.22±0.13 log MAR. Primary closure of hole was achieved in 29(96.7%). Significant mean difference was found in pre operative and post operative BCVA. CONCLUSION: Brilliant blue G exhibits sufficient staining qualities and safety profile to peel ILM in the management of full thickness macular hole with significant visual and anatomical improvement.

10.
Pak J Med Sci ; 32(1): 101-5, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27022354

RESUMEN

OBJECTIVE: To investigate the outcome of rhegmatogenous retinal detachment repair at Vitreoretinal unit of Jinnah Post Graduate Medical Centre Karachi in year 2014. METHODS: One hundred and three eyes of one hundred and three patients, who underwent three ports parsplana vitrectomy + band + silicone oil, three ports pars plana vitrectomy + silicone oil, three ports pars plana vitrectomy + C3F8 for rhegmatogenous retinal detachment (RRD) repair, at Jinnah Post Graduate Medical Centre, were included in this observational prospective study. Parsplana vitrectomy was done using 23G vitrectomy system. Duration of study was one year. Removal of silicone oil (ROSO) was done on the basis of completely flat retina at least for eight weeks or because of complications due to silicone oil. Patients were followed up post operatively on day one and after one week and then at four weekly interval till the end of the study. RESULTS: Anatomical success was achieved in 91 eyes (88.3%). However in 12 eyes (11.7%) retina redetached after removal of silicone oil. Functional success achievement of visual acuity of 3/60 or better was achieved in 85 (82.5%) of eyes post operatively after removal of silicone oil or absorption of gas C3F8 as the case may be. CONCLUSION: Re-detachment is common after removal of silicone oil and incidence of re-detachment is related to the degree of preoperative PVR and location of breaks. Re-detachment occurs more commonly if the breaks are inferiorly located as compared to the superior ones.

11.
Pak J Med Sci ; 31(4): 895-8, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26430425

RESUMEN

OBJECTIVE: To analyze the frequency of hepatitis B and C in patients undergoing cataract surgery. METHODS: This descriptive study was conducted at department of Ophthalmology Jinnah Post Graduate Medical Centre. The duration of study was seven months from May 2013 to November 2013. After taking informed consent from the patient and hospital ethical committee all patients presenting with cataract and undergoing cataract surgery were evaluated for the existence of hepatitis C and B. Diagnosis of hepatitis C or B was made on the criteria that a patient must be positive for either Anti-HCV or HBsAg or both. Proformas were filled and data was collected and analysis was done. Pearson's correlation coefficients were calculated to calculate the occurrence of hepatitis C and B in general population undergoing cataract surgery. RESULTS: Six hundred and forty-eight patients were operated on for cataract surgery at Jinnah Post Graduate Medical Centre during the study period. Mean age of patients was 63 years, 300 (46.29%) were male and 348 (53.70%) female. Out of them 57 (8.79%) patients were carriers of either Hepatitis C or B. Hepatitis B accounted for 17 cases (2.62%) however Hepatitis C positive were 40 cases (6.17%). Nobody was simultaneously affected by both hepatitis C and B. CONCLUSION: Significant number of asymptomatic carriers of hepatitis C and B were found in preoperative cataract patients. It is recommended that preoperative screening of all cataract patients should be done so that asymptomatic carriers might not become a threat for spread of disease.

12.
Pak J Med Sci ; 30(6): 1383-7, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25674143

RESUMEN

OBJECTIVE: To assess the effectiveness of intravitreal injection of Bevacizumab in the treatment of diabetic macular edema. METHODS: This case series was conducted at Department of Ophthalmology, Jinnah Post Graduate Medical Centre (JPMC), Karachi. The duration of study was six months from May 26, 2011 to November 25, 2011. The study group comprised of 54 patients of the Diabetic Macular Edema (DME). Intravitreal injection of 1.25 mg of bevacizumab (Avastin) was injected 3.5 mm from the limbus under topical anaesthetic drops. Post procedure follow up was scheduled on 1(st) post procedure day and after one month. Post procedure Optical Coherence tomography (OCT) was performed in all patients 1 week before and 1(st) month after 1(st) injection. The results were statistically analyzed through SPSS 17. RESULTS: Out of the 54 Eyes of 54 Patients who were given the Intravitreal injection of Avastin (Bevacizumab), 43 Eyes (79.6%) showed more than ten percent decrease in macular thickness from pre-injection thickness, 10 Eyes (18.5%) showed less than ten percent decrease and 1 Eye (1.9%) showed increase in macular thickness post operatively after one month. CONCLUSIONS: Intravitreal injection of Bevacizumab (Avastin) is effective in the treatment of diabetic macular edema.

13.
Biosensors (Basel) ; 13(5)2023 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-37232860

RESUMEN

Surface-enhanced Raman spectroscopy (SERS) applications in clinical diagnosis and spectral pathology are increasing due to the potential of the technique to bio-barcode incipient and differential diseases via real-time monitoring of biomarkers in fluids and in real-time via biomolecular fingerprinting. Additionally, the rapid advancements in micro/nanotechnology have a visible influence in all aspects of science and life. The miniaturization and enhanced properties of materials at the micro/nanoscale transcended the confines of the laboratory and are revolutionizing domains such as electronics, optics, medicine, and environmental science. The societal and technological impact of SERS biosensing by using semiconductor-based nanostructured smart substrates will be huge once minor technical pitfalls are solved. Herein, challenges in clinical routine testing are addressed in order to understand the context of how SERS can perform in real, in vivo sampling and bioassays for early neurodegenerative disease (ND) diagnosis. The main interest in translating SERS into clinical practice is reinforced by the practical advantages: portability of the designed setups, versatility in using nanomaterials of various matter and costs, readiness, and reliability. As we will present in this review, in the frame of technology readiness levels (TRL), the current maturity reached by semiconductor-based SERS biosensors, in particular that of zinc oxide (ZnO)-based hybrid SERS substrates, is situated at the development level TRL 6 (out of 9 levels). Three-dimensional, multilayered SERS substrates that provide additional plasmonic hot spots in the z-axis are of key importance in designing highly performant SERS biosensors for the detection of ND biomarkers.


Asunto(s)
Técnicas Biosensibles , Enfermedades Neurodegenerativas , Óxido de Zinc , Humanos , Óxido de Zinc/química , Reproducibilidad de los Resultados , Enfermedades Neurodegenerativas/diagnóstico , Espectrometría Raman/métodos , Técnicas Biosensibles/métodos , Biomarcadores
14.
Biosens Bioelectron ; 219: 114843, 2023 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-36327563

RESUMEN

Emerging antibiotic resistant bacteria constitute one of the biggest threats to public health. Surface-enhanced Raman scattering (SERS) is highly promising for detecting such bacteria and for antibiotic susceptibility testing (AST). SERS is fast, non-destructive (can probe living cells) and it is technologically flexible (readily integrated with robotics and machine learning algorithms). However, in order to integrate into efficient point-of-care (PoC) devices and to effectively replace the current culture-based methods, it needs to overcome the challenges of reliability, cost and complexity. Recently, significant progress has been made with the emergence of both new questions and new promising directions of research and technological development. This article brings together insights from several representative SERS-based AST studies and approaches oriented towards clinical PoC biosensing. It aims to serve as a reference source that can guide progress towards PoC routines for identifying antibiotic resistant pathogens. In turn, such identification would help to trace the origin of sporadic infections, in order to prevent outbreaks and to design effective medical treatment and preventive procedures.


Asunto(s)
Técnicas Biosensibles , Sistemas de Atención de Punto , Reproducibilidad de los Resultados , Bacterias , Antibacterianos/farmacología , Espectrometría Raman/métodos
15.
PeerJ Comput Sci ; 7: e615, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34395860

RESUMEN

Navigation based task-oriented dialogue systems provide users with a natural way of communicating with maps and navigation software. Natural language understanding (NLU) is the first step for a task-oriented dialogue system. It extracts the important entities (slot tagging) from the user's utterance and determines the user's objective (intent determination). Word embeddings are the distributed representations of the input sentence, and encompass the sentence's semantic and syntactic representations. We created the word embeddings using different methods like FastText, ELMO, BERT and XLNET; and studied their effect on the natural language understanding output. Experiments are performed on the Roman Urdu navigation utterances dataset. The results show that for the intent determination task XLNET based word embeddings outperform other methods; while for the task of slot tagging FastText and XLNET based word embeddings have much better accuracy in comparison to other approaches.

16.
Nanoscale ; 13(27): 11593-11634, 2021 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-34231627

RESUMEN

In recent years, bioanalytical surface-enhanced Raman spectroscopy (SERS) has blossomed into a fast-growing research area. Owing to its high sensitivity and outstanding multiplexing ability, SERS is an effective analytical technique that has excellent potential in bioanalysis and diagnosis, as demonstrated by its increasing applications in vivo. SERS allows the rapid detection of molecular species based on direct and indirect strategies. Because it benefits from the tunable surface properties of nanostructures, it finds a broad range of applications with clinical relevance, such as biological sensing, drug delivery and live cell imaging assays. Of particular interest are early-stage-cancer detection and the fast detection of pathogens. Here, we present a comprehensive survey of SERS-based assays, from basic considerations to bioanalytical applications. Our main focus is on SERS-based pathogen detection methods as point-of-care solutions for early bacterial infection detection and chronic disease diagnosis. Additionally, various promising in vivo applications of SERS are surveyed. Furthermore, we provide a brief outlook of recent endeavours and we discuss future prospects and limitations for SERS, as a reliable approach for rapid and sensitive bioanalysis and diagnosis.


Asunto(s)
Nanoestructuras , Espectrometría Raman , Propiedades de Superficie
17.
Nanoscale ; 13(32): 13906, 2021 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-34477665

RESUMEN

Correction for 'Surface-enhanced Raman spectroscopy for bioanalysis and diagnosis' by Muhammad Ali Tahir et al., Nanoscale, 2021, 13, 11593-11634, DOI: .


Asunto(s)
Espectrometría Raman
18.
RSC Adv ; 9(12): 6793-6803, 2019 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-35518460

RESUMEN

Nanosensors with high sensitivity utilize electrical, optical, and acoustic properties to improve the detection limits of analytes. The unique and exceptional properties of nanomaterials (large surface area to volume ratio, composition, charge, reactive sites, physical structure and potential) are exploited for sensing purposes. High-sensitivity in analyte recognition is achieved by preprocessing of samples, signal amplification and by applying different transduction approaches. In this review, types of signals produced and amplified by nanosensors (based on transducers) are presented, to sense exceptionally small concentrations of analytes present in a sample. The use of such nanosensors, sensitivity and selectivity can offer different advantages in biomedical applications like earlier detection of disease, toxins or biological threats and create significant improvements in clinical as well as environmental and industrial outcomes. The emerging discipline of nanotechnology at the boundary of life sciences and chemistry offers a wide range of prospects within a number of fields like fabrication and characterization of nanomaterials, supramolecular chemistry, targeted drug supply and early detection of disease related biomarkers.

19.
J Hazard Mater ; 346: 27-35, 2018 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-29232614

RESUMEN

We report a biosensor that combines the construction of a three-dimensional nanocomposite with electrochemical methods for the detection of viruses in plants. This is the first report, where carbon nanotubes are used as a conductive frame to anchor highly electrolytic agglomerates of copper nanoparticles to detect agroviruses. Morphological analysis of nanocomposite revealed the presence of carbon nanotubes having a diameter of 50-100nm with copper nanoparticles of 20-100nm, attached in the form of bunches. This material was applied to assess the infection caused by geminiviruses which are a major threat to the cotton plants in Asian and African countries. The hybridization events were studied by monitoring differential pulse voltammetry signals using methylene blue as a redox indicator. In the presence of target DNA, sensor signals decreased from 7×10-4 to 1×10-4Ampere. The probe exhibited 97.14% selectivity and the detection limit was found to be 0.01ngµL-1. The developed biosensor is stable for at least four weeks, losing only 4.3% of the initial signal value. This sensor was able to detect the presence of viruses in sap extracted from cotton leaves, thus providing a promising platform to detect a range of other crops-infecting viruses.


Asunto(s)
Begomovirus/aislamiento & purificación , Técnicas Biosensibles , Gossypium/virología , Hojas de la Planta/virología , Cobre/química , Sondas de ADN , ADN Viral/análisis , ADN Viral/química , Técnicas Electroquímicas , Nanopartículas del Metal/química , Nanocompuestos/química , Nanotubos de Carbono/química
20.
J Hazard Mater ; 342: 96-106, 2018 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-28823921

RESUMEN

Nanotechnology holds great promise for the fabrication of versatile materials that can be used as sensor platforms for the highly selective detection of analytes. In this research article we report a new nanohybrid material, where 3D imprinted nanostructures are constructed. First, copper nanoparticles are deposited on carbon nanotubes and then a hybrid structure is formed by coating molecularly imprinted polymer on 3D CNTs@Cu NPs; and a layer by layer assembly is achieved. SEM and AFM revealed the presence of Cu NPs (100-500nm) anchored along the whole length of CNTs, topped with imprinted layer. This material was applied to fabricate an electrochemical sensor to monitor a model veterinary drug, chloramphenicol. The high electron transfer ability and conductivity of the prepared material produced sensitive response, whereas, molecular imprinting produces selectivity towards drug detection. The sensor responses were found concentration dependent and the detection limit was calculated to be 10µM (S/N=3). Finally, we showed how changing the polymer composition, the extent of cross linking, and sensor layer thickness greatly affects the number of binding sites for the recognition of drug. This work paves the way to build variants of 3D imprinted materials for the detection of other kinds of biomolecules and antibiotics.


Asunto(s)
Antibacterianos/química , Cloranfenicol/química , Cobre/química , Nanotubos de Carbono/química , Polímeros/química , Antibacterianos/análisis , Cloranfenicol/análisis , Límite de Detección , Impresión Molecular , Nanopartículas , Nanotecnología
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