Mashooq Khan

Removal of Lead from Aqueous Solution by an Efficient Low Cost Biosorbent

Abstract Removal of Pb(II) ion from aqueous solution on modified sawdust obtained from Morus alba was investigated. The sample was characterized by BET surface area, EDX, FTIR and Zeta potential technique. The surface contains carbonyl and hydroxyl functional groups which act as binding sites for Pb(II) ion. Adsorption kinetics of Pb(II) on sawdust was tested by pseudo first order, Elovich and parabolic diffusion kinetic equations. The adsorption data were found to fit to Freundlich, Langmuir and Tempkin isotherms. The rate of adsorption was high at high temperature. Thermodynamic parameters like ΔH, ΔS and ΔG were calculated from the kinetic data. The positive values of ΔS reflect some structural exchange among the active site of the adsorbent and metal ion. The negative values of Gibbs free energy (ΔG) show the spontaneous nature of the process.

Combination of nano-material enrichment and dead-end filtration for uniform and rapid sample preparation in matrix-assisted laser desorption/ionization mass spectrometry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a fast analysis tool for the detection of a wide range of analytes. However, heterogeneous distribution of matrix/analyte cocrystal, variation in signal intensity and poor experimental reproducibility at different locations of the same spot means difficulty in quantitative analysis. In this work, carbon nanotubes (CNTs) were employed as adsorbent for analyte cum matrix on a conductive porous membrane as a novel mass target plate. The sample pretreatment step was achieved by enrichment and dead-end filtration and dried by a solid-liquid separation. This approach enables the homogeneous distribution of analyte in the matrix, good shot-to-shot reproducibility in signals and quantitative detection of peptide and protein at different concentrations with correlation coefficient (R2) of 0.9920 and 0.9909, respectively. The simple preparation of sample in a short time, uniform distribution of analyte, easy quantitative detection, and high reproducibility makes this technique useful and may diversify the application of MALDI-MS for quantitative detection of a variety of proteins.

MoS2-LA-PEI nanocomposite carrier for real-time imaging of ATP metabolism in glioma stem cells co-cultured with endothelial cells on a microfluidic system

Stimuli-responsive carriers have extensively attracted attention in recent years. However, long-term and real-time tracking ability with stimuli-responsive carrier is still in its infant stage due to the limitations such as, low efficacy, instability and cytotoxicity in a bio-environment. In this work, we developed a reduction-sensitive carrier composed of lipoic acid-modified low molecular weight polyethyleneimine (LA-PEI) and large surface ratio MoS2 nanosheet integrated via disulfide bond to mimic a high molecular weight PEI. The positively charged carriers loading negatively charged aptamer enter the cells for a real time long-term tracking of adenosine triphosphate (ATP) metabolism in glioma stem cells (GSCs) when stimulated by TGFβ factor secreted from HUVECs. We envision that MoS2-LA-PEI carrier has a promising potential for delivery and monitoring the changes in live cells with low cytotoxicity and high efficiency.

Tuning of Activated Carbon for Solvent-Free Oxidation of Cyclohexane

Activated carbon (AC) was prepared from carbonization of phosphoric acid soaked peanut shell at 380°C under inert atmosphere followed by activation with hydrogen peroxide. The AC was characterized by SEM, EDX, FTIR, TGA, and BET surface area and pore size analyzer. The potential of AC as a catalyst for solvent-free oxidation of cyclohexane to cyclohexanol and cyclohexanone (the mixture is known as KA oil) in the presence of molecular oxygen at moderate temperature was investigated in a self-designed double-walled three-necked batch reactor. The effect of different reaction parameters/additive was optimized. The maximum productivity value (2.14 mmolg−1 h−1, without base, and 4.85 mmolg−1 h−1, with 0.2 mmol NaOH) of the desired product was achieved under optimal reaction parameters: vol 12.5 mL, cat 0.4 g, time 14 h, oxygen flow 40 mL/min (pO2 760 Torr), stirring 1100 rpm, and temp 75°C. The AC shows recyclability for multiple runs without any significant loss in activity. Thus, the AC can be an efficient catalyst, due to low cost, ease of synthesis, easy recovery, nonleaching, and recyclability for multiple uses for the solvent-free oxidation of cyclohexane.

Advances in tumor-endothelial cells co-culture and interaction on microfluidics

The metastasis in which the cancer cells degrade the extracellular matrix (ECM) and invade to the surrounding and far tissues of the body is the leading cause of mortality in cancer patients. With a lot of advancement in the field, yet the biological cause of metastasis are poorly understood. The microfluidic system provides advanced technology to reconstruct a variety of in vivo-like environment for studying the interactions between tumor cells (TCs) and endothelial cells (ECs). This review gives a brief account of both two-dimensional models and three-dimensional microfluidic systems for the analysis of TCs-ECs co-culture as well as their applications to anti-cancer drug screening. Furthermore, the advanced methods for analyzing cell-to-cell interactions at single-cell level were also discussed.

Controlled grafted poly(quaternized-4-vinylpyridine-co-acrylic acid) brushes attract bacteria for effective antimicrobial surfaces

Copolymer poly(quaternized-4-vinylpyridine-co-acrylic acid) (P(Q4VP-co-AA)) brushes with an adsorbed amino acid (l-glutamine (GA)) were grafted onto surfaces as a means of attracting, contact-killing, and releasing bacteria. The substrates, silicon wafer (SW), glass, and PDMS, were coated with 7-octenyltrichlorosilane (7OTS), and this was followed by surface-initiated reversible addition-fragmentation transfer (SI-RAFT) polymerization. The 7OTS allowed easy control of the grafting density, and a maximum grafting density of 0.36 chains per nm2 was obtained. The GA was initially adsorbed to the P(Q4VP-co-AA) brushes, and ultimately desorbed in a microbial environment-created concentration gradient, causing microbial movement toward the decorated surfaces. The P(Q4VP-co-AA) brushes at SW, glass, and PDMS substrates enabled the contact-killing of 90 ± 4, 93 ± 5, and 92 ± 3% of Escherichia coli and 92 ± 4, 93 ± 3, and 91 ± 4% of Staphylococcus aureus, respectively, from microbial concentrations of 1 × 105 CFU mL-1 and 30 min exposures. After contact-killing, these brushes completely released the microbes when they were dipped in NaCl (1 M) solution for 5 min. The ease of controlling the grafting density and substrate modification as well as the microbial attraction capability, high contact-killing efficiency, and self-sterilizing make P(Q4VP-co-AA)-GA brushes a useful material for the development of multi-functional antimicrobial substrates.

Microfluidic Devices in the Fast-Growing Domain of Single-Cell Analysis

Recent advances in cellular analysis revealed that the seemingly identical cells are heterogeneous in term of functionality, compositions, and genetic performance. These differences cause difficulty in the diagnostic for a specific model of disease. Detection of biomolecules such as DNA, RNA, and protein or analysis of cell(s), detection of cell surface molecules, and secreted protein, can help us to improve the understanding of a targeted disease and development of new diagnostic and therapeutic approaches. A single-cell includes the minute quantity of these target molecules. Microfluidic devices have the ability to capture a single-cell and its lysate into a pico or femtoliter volumes droplet, or micro-well thus preventing dilution and limiting diffusion. In this review we described the advancement and limitations in microfluidic techniques used toward single-cells analysis.

Measurement of Cell-Matrix Adhesion at Single-Cell Resolution Reveals the Functions of Biomaterials for Adherent Cell Culture

Cell adhesion is essential for a cell to maintain its functions, and biomaterials acting as the extracellular matrix (ECM) play a vital role. However, conventional methods for evaluating the functions of biomaterials become insufficient and sometimes incorrect when we give a deeper insight into single-cell research. In this work, we reported a novel methodology for the measurement of cell-matrix adhesion at single-cell resolution that could precisely evaluate the functions of biomaterials for adherent cell culture. A microfludic device, a live single-cell extractor (LSCE), was used for cell extraction. We applied this method to evaluate various modified biomaterials. The results indicated that poly(l-polylysine) (PLL)-coated glass and fibronection (FN)-coated glass slides showed the best biocompatibility for adherent cell culture following by the (3-aminopropyl)triethoxysilane (APTES)-coated glass, while piranha solution treated glass slide and octadecyltrichlorosilane (OTS)-coated glass showed weak biocompatibilities. Furthermore, APTES, PLL, and FN modifications enhanced the cell heterogeneity, while the OTS modification weakened the cell heterogeneity compare to the initial piranha solution treated glass. The method not only clarified the cell-matrix adhesion strength at single-cell resolution but also revealed the influences of biomaterials on cell-matrix adhesion and heterogeneity of cell-matrix adhesion for adherent cell culture. It might be a general strategy for precise evaluation of biomaterials.

Thermodynamic and kinetic studies of adsorptive removal of toluidine blue by activated carbon from olive pit

aDepartment of Chemistry, University of Malakand, Chakdara 18800, Pakistan, emails: sadiq@uom.edu.pk, mohammad_sadiq26@yahoo.com (M. Sadiq), razia.aman@yahoo.com (R. Aman), sohail850@gmail.com (M. Sohail Ahmad), muhammadali041988@yahoo.com (M. Ali) bDepartment of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University, Beijing 100084, China, emails: mashooq_khan@yahoo.com, khan1985@mail.tsinghua.edu.cn cSchool of Applied Chemical Engineering, Kyungpook National University, Daegu, Korea, email: saimasadiq1978@yahoo.com dDepartment of Chemistry, National Center of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan, email: rahmat_chemistpk@yahoo.com