Sara Riaz

Bio: Sara Riaz is an academic researcher from COMSATS Institute of Information Technology. The author has contributed to research in topics: Materials science & Medicine. The author has an hindex of 6, co-authored 21 publications receiving 159 citations. Previous affiliations of Sara Riaz include East China University of Science and Technology.

Silver nanoparticles on cotton swabs for improved surface-enhanced Raman scattering, and its application to the detection of carbaryl

Abstract: We describe the preparation of a cotton swab for use in surface enhanced Raman scattering (SERS) by assembling silver nanoparticles (Ag-NPs) on common cotton. The flexibility of such cotton swabs allows for a close contact with sample surfaces by swabbing. This can considerably improve the sample collection efficiency. These cotton swabs exhibit excellent SERS activity as shown by the detection of rhodamine 6G at 0.81 pM concentration. The reproducibility of the intensity of SERS peaks is within 10 %. The applicability is demonstrated by in-situ detection of the fungicide carbaryl on a cucumber with an irregular surface. This combination of superior SERS activity, high reproducibility, accessibility in irregularly-shaped matrices and low-cost production indicates that such swabs offer a large potential in analytical SERS.

Perylene diimide/MXene-modified graphitic pencil electrode-based electrochemical sensor for dopamine detection

Abstract: The synthesis of novel architecture comprising perylene diimide (PDI)-MXene (Ti3C2TX)-integrated graphitic pencil electrode for electrochemical detection of dopamine (DA) is reported. The good electron passage between PDI-MXene resulted in an unprecedented nano-adduct bearing enhanced electrocatalytic activity with low-energy electronic transitions. The anionic groups of PDI corroborated enhanced active surface area for selective binding and robust oxidation of DA, thereby decreasing the applied potential. Meanwhile, the MXene layers acted as functional conducive support for PDI absorption via strong H-bonding. The considerable conductivity of MXene enhanced electron transportation thus increasing the sensitivity of sensing interface. The inclusively engineered nano-adduct resulted in robust DA oxidation with ultra-sensitivity (38.1 μAμM−1cm−2), and low detection limit (240 nM) at very low oxidation potential (−0.135 V). Moreover, it selectively signaled DA in the presence of physiological interferents with wide linearity (100–1000 μM). The developed transducing interface performed well in human serum samples with RSD (0.1 to 0.4%) and recovery (98.6 to 100.2%) corroborating the viability of the practical implementation of this integrated system.

Functionalized Graphene Oxide Bridging between Enzyme and Au-Sputtered Screen-Printed Interface for Glucose Detection

Abstract: This work reports the fabrication of an electrochemical glucose biosensor based on functionalized graphene, assembled onto a gold-sputtered screen-printed electrode. With the aim of simplicity, versatility, and low cost, biosensors dually functionalized with graphene oxide containing excess carboxylic acids and thiol functionality were synthesized and characterized by Fourier transform infrared, Raman, and UV–vis spectroscopy. The increased carboxylic groups of the graphene backbone provided more active sites for the remote functional groups of glucose oxidase during 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide-assisted immobilization. The modified electrode interface was characterized by scanning electron microscopy, atomic force microscopy, and cyclic voltammetry. This hybrid electrode interface showed higher sensitivity for glucose (3.1732 μA mM–1 cm–2) with a detection limit of 0.3194 mM (S/N = 3). Furthermore, the fabricated biosensor demonstrated a linear response in 3–9 mM glucose concentration ...

Cu@Ag/β-AgVO3 as a SERS substrate for the trace level detection of carbamate pesticides

Abstract: A Surface Enhanced Raman Scattering (SERS) substrate based on Ag/β-AgVO3 nanobelts deposited on copper foil (Cu@Ag/β-AgVO3) was used for the detection of carbamate pesticides: carbofuran, carbaryl, isoprocarb and propoxur. Cu@Ag/β-AgVO3 has shown an excellent SERS activity for carbamate pesticides compared to silver nanoparticles (AgNPs). Under optimized conditions, detection limits of 2.5 pM, 10 pM, 50 pM and 75 pM were obtained for carbaryl, carbofuran, isoprocarb and propoxur respectively, suggesting that Cu@Ag/β-AgVO3 is a good candidate for use as a SERS substrate for the trace level detection of these pesticides.

Multifunctional Skin-Inspired Flexible Sensor Systems for Wearable Electronics

Abstract: DOI: 10.1002/admt.201800628 applications (e.g., soft robotics, medical devices).[1–6] Despite state-of-the-art bulkbased planar integrated-circuit devices, their rigid and brittle nature gives rise to the incompatibility with curvilinear and soft human bodies, restricting the development of newborn human-friendly interactive electronics. In contrast, the bendable and flexible wearable electronics could be conformally attached onto human bodies almost without discomfort and succeed in performing a great deal of sensing functionalities. Realization of such promising goals requires the flexible sensor platforms provided with crucial characteristics of light weight, ultrathinness, superior flexibility, stretchability, high sensitivity as well as rapid response.[7–10] Inspired by the perceptive features of human skins, the wearable sensor systems are capable of acquiring abundant information from the external environment with the assistance of sensing modules, such as pressure sensors, strain sensors, temperature sensors, etc.[11] A typical example is their application in prosthetics that could afford the capacity to perceive touch or temperature for the disabled.[12] Additionally, the wearable sensor systems are able to identify physical or chemical signals produced by the human body, providing promising opportunities to evaluate health states.[5,13–15] Conventional skin-like sensor platforms primarily comprise one or two sensing modules, data processing units, and power supplies. Their unitary functionality, however, cannot satisfy the increasing demands of IoTs. Recently, the rapid advances in novel sensing materials, fabrication strategies, and innovative electronic constitution contribute to the development of versatile integration of multimodal sensors, which could synchronously distinguish diverse stimuli from the complex environment and monitor multiple vital signs from the human body.[16,17] In spite of several attempts done in terms of such multimodal sensor systems, one of the cumbersome issues originates from the crosscoupling effect among different categories of signals simultaneously generated by various sensors. Furthermore, the skin-like multiple sensor systems usually suffer from the limited number of repeated use, resulting in their high use-cost. The development of separable versatile devices may address this issue with one layer realized by costeffective materials and fabrication manners for disposable use and the other composed of relatively expensive components for repeatable applications.[18] Additionally, the multiple bending or Skin-inspired wearable devices hold great potentials in the next generation of smart portable electronics owing to their intriguing applications in healthcare monitoring, soft robotics, artificial intelligence, and human–machine interfaces. Despite tremendous research efforts dedicated to judiciously tailoring wearable devices in terms of their thickness, portability, flexibility, bendability as well as stretchability, the emerging Internet of Things demand the skininterfaced flexible systems to be endowed with additional functionalities with the capability of mimicking skin-like perception and beyond. This review covers and highlights the latest advances of burgeoning multifunctional wearable electronics, primarily including versatile multimodal sensor systems, self-healing material-based devices, and self-powered flexible sensors. To render the penetration of human-interactive devices into global markets and households, economical manufacturing techniques are crucial to achieve large-scale flexible systems with high-throughput capability. The booming innovations in this research field will push the scientific community forward and benefit human beings in the near future.

Application of graphene in energy storage device – A review

Abstract: Most applications in energy storage devices revolve around the application of graphene. Graphene is capable of enhancing the performance, functionality as well as durability of many applications, but the commercialization of graphene still requires more research activity being conducted. This investigation explored the application of graphene in energy storage device, absorbers and electrochemical sensors. To expand the utilization of graphene, its present limitations must critically be addressed to improve their current performance. Again, in terms of applications, the advantages of graphene has widened their application in both electroanalytical and electrochemical sensors. These good characteristics of graphene must be extended further and improved to make them suitable for other applications. Critical study of facile synthesis of graphene coupled with detailed investigation into the structure of graphene oxide at the molecular level will equally improve the performance of this novel material. Effects of defects on the performance of graphene oxide was also identified as another key area of research that needs much attention to accelerate the commercialization of this material. With the rapid growth in the application of the graphene in different energy storage/conversion applications, it is essential to summarize and discuss the up-to-date progress in the application of graphene in these fields.

Toward Flexible Surface-Enhanced Raman Scattering (SERS) Sensors for Point-of-Care Diagnostics

Abstract: Surface-enhanced Raman scattering (SERS) spectroscopy provides a noninvasive and highly sensitive route for fingerprint and label-free detection of a wide range of molecules. Recently, flexible SERS has attracted increasingly tremendous research interest due to its unique advantages compared to rigid substrate-based SERS. Here, the latest advances in flexible substrate-based SERS diagnostic devices are investigated in-depth. First, the intriguing prospect of point-of-care diagnostics is briefly described, followed by an introduction to the cutting-edge SERS technique. Then, the focus is moved from conventional rigid substrate-based SERS to the emerging flexible SERS technique. The main part of this report highlights the recent three categories of flexible SERS substrates, including actively tunable SERS, swab-sampling strategy, and the in situ SERS detection approach. Furthermore, other promising means of flexible SERS are also introduced. The flexible SERS substrates with low-cost, batch-fabrication, and easy-to-operate characteristics can be integrated into portable Raman spectroscopes for point-of-care diagnostics, which are conceivable to penetrate global markets and households as next-generation wearable sensors in the near future.

Recent progress in surface enhanced Raman spectroscopy for the detection of environmental pollutants

Abstract: Surface enhanced Raman spectroscopy (SERS) has emerged as one of the most promising analytical tools in recent years. Due to advantageous features such as sensitivity, specificity, ease of operation and rapidity, SERS is particularly well suited for environmental analysis. We summarize here some considerations with respect to the detection of pollutants by SERS and provide an overview on recent achievements in the determination of organic pollutants, heavy metal ions, and pathogens. Following an introduction into the topic and considering aspects of sensitivity, selectivity, reproducibility and portability, we are summarizing applications of SERS in the detection of pollutants, with sections on organic pollutants (pesticides, PAHs and PCBs, explosives), on heavy metal ions, and on pathogens. In addition, we discuss current challenges and give an outlook on applications of SERS in environmental analysis. Contains 174 references.