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A composite of citrate-modified β-cyclodextrin (CIT-BCD) and Fe3O4 was prepared by coprecipitation for a non-enzymatic cholesterol sensor application. Characterization using X-ray diffraction spectroscopy confirmed the spinel structure of Fe3O4, whereas infrared spectroscopy indicated that the composite of CIT-BCD@Fe3O4 was successfully synthesized. The cholesterol was detected on the basis of the competition of the inclusion complex formation between β-cyclodextrin (BCD) and cholesterol, and between BCD and methylene blue (MB), and the magnetic particles of Fe3O4 were used as the support medium of BCD. BCD was modified with citrate to improve its cholesterol loading capacity for a computational study through molecular docking simulation, which confirmed that cholesterol formed higher complex stabilities with both BCD and CIT-BCD than with MB, with the ΔGbinding values, of the complexes being -6.4 and -5.7 kcal/mol, respectively. A ratio of 3% (w/w) CIT-BCD@Fe3O4 nanocomposite and a contact time of 10 min were then found as optimum conditions. Furthermore, amperometric measurements performed using a screen-printed carbon electrode at an applied potential of -0.43 V (vs Ag/AgCl) with a measurement time of 90 s was conducted to detect the MB released from the system. Amperometry results showed good linearity (R2 > 0.99) in the cholesterol concentration range of 0-100 µM with an estimated limit of detection of 3.93 µM. Good selectivity towards ascorbic acid, palmitic acid, tyrosine, and threonine was observed, whereas a significant change in current response was found in the presence of arginine. The developed method was successfully demonstrated to determine cholesterol levels in commercial corned beef samples. The method was also successfully validated by HPLC, indicating that the developed sensor is promising for real applications in cholesterol detection, especially in the matrix of meat samples. [ABSTRACT FROM AUTHOR]

The health care industry is continuously revolutionizing and advancing towards developing more efficient system suitable for human body. Today implantable devices have become a more interesting topic in health care services which primarily started with the pacemakers. Since then it is continuously evolving due to its non-invasive nature, instant monitoring and diagnosis, and periodic simulation. The main goal of these implantable devices is to efficiently monitor or inspect various ailments in the body and then transmits this to the server or base station. For proper communication between the implant and the base station, antenna design is of prime importance. In this paper MEMS based differentially fed dual band antenna has been proposed and can be used both in Medical Implant Communication Service (MICS) band for transmission of data and industrial, scientific and medical (ISM) band for wake-up purpose. The proposed antenna has been simulated for free space scenario and has been found to radiate in both MICS & ISM band with S11 of −17.62 dB and −14.31 dB respectively. Subsequently the antenna is inserted within a skin mimicking model with equivalent dielectric features and the results show variation in radiation characteristics between free space condition and within skin phantom. The design of the antenna has been optimized in such a way that minimum deviation occurs between the two conformal conditions. With the use of differential feeding technique performance of the antenna is quite enhanced in terms of various parameters when compared with single feed.

The structure and dynamics of water droplets on a bilayer graphene surface are investigated using molecular dynamics simulations. The effects of solid/water and air/water interfaces on the local structure of water droplets are analyzed in terms of the hydrogen bond distribution and tetrahedral order parameter. It is found that the local structure in the core region of a water droplet is similar to that in liquid water. On the other hand, the local structure of water molecules at the solid/water and air/water interfaces, referred to as the interface and surface regions, respectively, consists mainly of three-coordinated molecules that are greatly distorted from a tetrahedral structure. This study reveals that the dynamics in different regions of the water droplets affects the intermolecular vibrational density of states: It is found that in the surface and interface regions, the intensity of vibrational density of states at ∼50 cm−1 is enhanced, whereas those at ∼200 and ∼500 cm−1 are weakened and redshifted. These changes are attributed to the increase in the number of molecules having fewer hydrogen bonds in the interface and surface regions. Both single-molecule and collective orientation relaxations are also examined. Single-molecule orientation relaxation is found to be marginally slower than that in liquid water. On the other hand, the collective orientation relaxation of water droplets is found to be significantly faster than that of liquid water because of the destructive correlation of dipole moments in the droplets. The negative correlation between distinct dipole moments also yields a blueshifted libration peak in the absorption spectrum. It is also found that the water–graphene interaction affects the structure and dynamics of the water droplets, such as the local water structure, collective orientation relaxation, and the correlation between dipole moments. This study reveals that the water/solid and water/air interfaces strongly affect the structure and intermolecular dynamics of water droplets and suggests that the intermolecular dynamics, such as energy relaxation dynamics, in other systems with interfaces are different from those in liquid water. [ABSTRACT FROM AUTHOR]