Capacitance of Flexible Polymer/Graphene Microstructures with High Mechanical Strength.

Carbon-modified fibrous structures with high biocompatibility have attracted much attention due to their low cost, sustainability, abundance, and excellent electrical properties. However, some carbon-based materials possess low specific capacitance and electrochemical performance, which pose significant challenges in developing electronic microdevices. In this study, we report a microfluidic-based technique of manufacturing alginate hollow microfibers incorporated by water dispersed modified graphene (bovine serum albumin-graphene). These architectures successfully exhibited enhanced conductivity ∼20 times higher than alginate hollow microfibers without any significant change in the inner dimension of the hollow region (220.0 ± 10.0 µm) compared with pure alginate hollow microfibers. In the presence of graphene, higher specific surface permeability, active ion adsorption sites, and shorter pathways were created. These continuous ion transport networks resulted in improved electrochemical performance. The desired electrochemical properties of the microfibers make alginate/graphene hollow fibers an excellent choice for further use in the development of flexible capacitors with the potential to be used in smart health electronics.

Hydrodynamic Assembly of Astrocyte Cells in Conductive Hollow Microfibers.

The manufacturing of 3D cell scaffoldings provides advantages for modeling diseases and injuries as it enables the creation of physiologically relevant platforms. A triple-flow microfluidic device is developed to rapidly fabricate alginate/graphene hollow microfibers based on the gelation of alginate induced with CaCl2 . This five-channel microdevice actualizes continuous mild fabrication of hollow fibers under an optimized flow rate ratio of 300:200:100 µL min-1 . The polymer solution is 2.5% alginate in 0.1% graphene and a 30% polyethylene glycol solution is used as the sheath and core solutions. The biocompatibility of these conductive microfibers by encapsulating mouse astrocyte cells (C8D1A) within the scaffolds is investigated. The cells can successfully survive both the manufacturing process and prolonged encapsulation for up to 8 days, where there is between 18-53% of live cells on both the alginate microfibers and alginate/graphene microfibers. These unique 3D hollow scaffolds can significantly enhance the available surface area for nutrient transport to the cells. In addition, these conductive hollow scaffolds illustrate unique advantages such as 0.728 cm3  gr-1 porosity and two times more electrical conductivity in comparison to alginate scaffolds. The results confirm the potential of these scaffolds as a microenvironment that supports cell growth.

An insight into fluorescence and magnetic resonance bioimaging using a multifunctional polyethyleneimine-passivated gadocarbon dots nanoconstruct assembled with AS1411.

A nanoassembly of PEI-passivated Gd@CDs, a type of aptamer, is presented which was designed and characterized in order to target specific cancer cells based on their recognition of the receptor nucleolin (NCL), which is overexpressed on the cell membrane of breast cancer cells for fluorescence and magnetic resonance imaging and treatment. Using hydrothermal methods, Gd-doped nanostructures were synthesized, then modified by a two-step chemical procedure for subsequent applications: the passivating of Gd@CDs with branched polyethyleneimine (PEI) (to form Gd@CDs-PEI1 and Gd@CDs-PEI2), and using AS1411 aptamer (AS) as a DNA-targeted molecule (to generate AS/Gd@CDs-PEI1 and AS/Gd@CDs-PEI2). Consequently, these nanoassemblies were constructed as a result of electrostatic interactions between cationic Gd@CDs-passivated PEI and AS aptamers, offering efficient multimodal targeting nanoassemblies for cancer cell detection. It has been demonstrated through in vitro studies that both types of AS-conjugated nanoassemblies are highly biocompatible, have high cellular uptake efficiency (equivalent concentration of AS: 0.25 µΜ), and enable targeted fluorescence imaging in nucleolin-positive MCF7 and MDA-MB-231 cancer cells compared to MCF10-A normal cells. Importantly, the as-prepared Gd@CDs, Gd@CDs-PEI1, and Gd@CDs-PEI2 exhibit higher longitudinal relaxivity values (r1) compared with the commercial Gd-DTPA, equal to 5.212, 7.488, and 5.667 mM-1s-1, respectively. Accordingly, it is concluded that the prepared nanoassemblies have the potential to become excellent candidates for cancer targeting and fluorescence/MR imaging agents, which can be applied to cancer imaging and personalized nanomedicine.

Advancement of Sensor Integrated Organ-on-Chip Devices.

Organ-on-chip devices have provided the pharmaceutical and tissue engineering worlds much hope since they arrived and began to grow in sophistication. However, limitations for their applicability were soon realized as they lacked real-time monitoring and sensing capabilities. The users of these devices relied solely on endpoint analysis for the results of their tests, which created a chasm in the understanding of life between the lab the natural world. However, this gap is being bridged with sensors that are integrated into organ-on-chip devices. This review goes in-depth on different sensing methods, giving examples for various research on mechanical, electrical resistance, and bead-based sensors, and the prospects of each. Furthermore, the review covers works conducted that use specific sensors for oxygen, and various metabolites to characterize cellular behavior and response in real-time. Together, the outline of these works gives a thorough analysis of the design methodology and sophistication of the current sensor integrated organ-on-chips.

Fabrication and evaluation of aptamer-conjugated paclitaxel-loaded magnetic nanoparticles for targeted therapy on breast cancer cells.

Targeted drug delivery vehicles make it possible to deliver anti-cancer drugs to the cells or tissues of interest. Aptamers are peptide or oligonucleotide molecules that can serve as targeting elements of drug carriers. In the current study, we evaluated the capacity of an aptamer-based drug carrier to deliver Paclitaxel (PTX) to cancer cells. After being synthesized, SPIONs@PTX-SYL3C aptamer was characterized using different methods, including differential light scattering (DLS), infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Encapsulation efficiency (EE) and loading efficiency (LE) were also evaluated. The carrier was applied on 4T1, MCF 7, and MCF-10A breast cell lines to evaluate its drug delivery potency and specificity. EE and LE were calculated to be 77.6% and 7.76%, respectively. MTT results revealed that aptameric SPIONs@PTX was more toxic than non-aptameric SPIONs@PTX. Flowcytometry analysis and DAPI staining confirmed that SPIONs@PTX-Aptamer had higher cell internalization rate when compared to non-targeted SPIONs@PTX. Our results indicate that aptamer-conjugated SPIONs@PTX has a good capacity in recognizing its target cells and inhibiting their growth and division.

Chemometrical-electrochemical investigation for comparing inhibitory effects of quercetin and its sulfonamide derivative on human carbonic anhydrase II: Theoretical and experimental evidence.

This paper reports results of a valuable study on investigation of inhibitory effects of the sulfonamide derivative of quercetin (QD) on human carbonic anhydrase II (CA-II) by electrochemical and chemometrical approaches. To achieve this goal, a glassy carbon electrode (GCE) was chosen as the sensing platform and different electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were used to investigate and comparing inhibitory effects of quercetin (Q) and QD on CA-II. By the use of EQUISPEC, SPECFIT, SQUAD and REACTLAB as efficient hard-modeling algorithms, bindings of Q and QD with CA-II were investigated and the results confirmed that the QD inhibited the CA-II stronger than Q suggesting a highly relevant role of QD's-SO2NH2 group in inhibiting activity and also was confirmed by docking studies. Finally, a novel EIS technique based on interaction of Q and CA-II was developed for sensitive electroanalytical determination of CA-II and in this section of our study, the sensitivity of the developed electroanalytical methodology was improved by the modification of the GCE was with multi-walled carbon nanotubes-ionic liquid.

Determination of cDNA encoding BCR/ABL fusion gene in patients with chronic myelogenous leukemia using a novel FRET-based quantum dots-DNA nanosensor.

In the present study, we developed a sensitive method based on fluorescence resonance energy transfer (FRET) for the determination of the BCR/ABL fusion gene, which is used as a biomarker to confirm the clinical diagnosis of both chronic myelogenous leukemia (CML) and acute lymphocytic leukemia (ALL). For this purpose, CdTe quantum dots (QDs) were conjugated to amino-modified 18-mer oligonucleotide ((N)DNA) to form the QDs-(N)DNA nanosensor. In the presence of methylene blue (MB) as an intercalator, the hybridization of QDs-(N)DNA with the target BCR/ABL fusion gene (complementary DNA), brings the MB (acceptor) at close proximity of the QDs (donor), leading to FRET upon photoexcitation of the QDs. The enhancement in the emission intensity of MB was used to follow up the hybridization, which was linearly proportional to concentration of the target complementary DNA in a range from 1.0 × 10-9 to 1.25 × 10-7 M. The detection limit of the proposed method was obtained to be 1.5 × 10-10 M. Finally, the feasibility and selectivity of the proposed nanosensor was evaluated by the analysis of derived nucleotides from both mismatched sequences and clinical samples of patients with leukemia as real samples.

A highly sensitive quantum dots-DNA nanobiosensor based on fluorescence resonance energy transfer for rapid detection of nanomolar amounts of human papillomavirus 18.

A very sensitive and convenient nanobiosensor based on fluorescence resonance energy transfer (FRET) was developed for the detection of a 22-mer oligonucleotides sequence in Human Papillomavirus 18 virus (HPV18) gene. For this purpose, water-soluble CdTe quantum dots (QDs) were synthesized and, subsequently, amino-modified 11-mer oligonucleotide as one of the two necessary probes was attached to QDs surface to form functional QDs-DNA conjugates. Right after addition of the QDs-DNA and a second Cyanine5 (Cy5)-labeled 11-mer oligonucleotide probe to the DNA target solution, the sandwiched hybrids were formed. The resulting hybridization brings the Cy5 fluorophore as the acceptor to close proximity of the QDs as donor, so that an effective transfer of energy from the excited QDs to the Cy5 probe would occur via FRET processing. The fluorescence intensity of Cy5 found to linearly enhance by increasing the DNA target concentration from 1.0 to 50.0nM, with a detection limit of 0.2nM. This homogeneous DNA detection method does not require excessive washing and separation steps of un-hybridized DNA, due to the fact that no FRET can be observed when the probes are not ligated. Finally, feasibility and selectivity of the proposed one-spot DNA detection nanobiosensor were investigated by analysis of derived nucleotides from HPV18 and mismatched sequences.

Determination of tramadol by dispersive liquid-liquid microextraction combined with GC-MS.

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 µg L(-1), respectively. The linear range was between 0.26 and 220.00 µg L(-1) (R(2) = 0.9970). The relative standard deviation for 50.00 µg L(-1) of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood.

Fabrication of a novel naltrexone biosensor based on a computationally engineered nanobiocomposite.

A computationally engineered impedimetric naltrexone (NLT) biosensor based on immobilization of bovine serum albumin (BSA) onto fullerene-C60/glassy carbon electrode (FLR/GCE) has been developed using initial characterization by computational methods and complementing them by experimental ones. Computational results showed that BSA hydrophobically binds to FLR which is energetically favorable and leads to the spontaneous formation of the stable nanobiocomposite and also showed that interaction of NLT with BSA is mainly driven by hydrogen bonding and hydrophobic interactions. Besides complementing the computational studies, experimental results showed that addition of FLR to the surface of the electrode facilitated electron transfer reactions, and also showed that the presence of BSA inhibits the interfacial electron transfer in some extent due to the non-conductive properties of BSA. The presence of NLT may form a negatively charged electroactive complex with BSA which repels the negatively charged redox probe and decelerates interfacial electron transfer leading to obvious faradaic impedance change. The faradaic impedance responses were linearly related to naltrexone concentration between 0.1 nM and 80 nM and limit of detection (LOD) was calculated to be 0.01 nM 3Sb/b. Finally, the proposed biosensor was successfully applied to determination of NLT in urine samples of both healthy and addict volunteers.