Synthesis of a novel multifunctional organic-inorganic nanocomposite for metal ions and organic dye removals.

In this study, we used solvent assisted mechano-synthesis strategies to form multifunctional organic-inorganic nanocomposites capable of removing both organic and inorganic contaminants. A zeolite X (Ze) and activated carbon (AC) composite was synthesized via state-of-the-art mechanical mixing in the presence of few drops of water to form Ze/AC. The second composite (Ze/L/AC) was synthesized in a similar fashion, however this composite had the addition of disodium terephthalate as a linker. Both materials, Ze/AC and Ze/L/AC, were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), Accelerated Surface Area and Porosimetry System (ASAP), and thermal gravimetric analysis (TGA). The SEM-EDS displayed the surface structure and composition of each material. The sodium, oxygen and carbon contents increased after linker connected Ze and AC. The P-XRD confirmed the crystallinity of each material as well as the composites, while FTIR indicated the function groups (C=C, O-H) in Ze/L/AC. The contaminant adsorption experiments investigated the effects of pH, temperature, and ionic strength on the adsorption of methylene blue (MB) and Co(II) for each material. In MB adsorption, the first-order reaction rate of Ze/L/AC (0.02 h-1) was double that of Ze/AC (0.01 h-1). The reaction rate of Ze/L/AC (4.8 h-1) was also extraordinarily higher than that of Ze/AC (0.6 h-1) in the adsorption of Co(II). Ze/L/AC composite achieved a maximum adsorption capacity of 44.8 mg/g for MB and 66.6 mg/g for Co(II) ions. The MB adsorption of Ze/AC and Ze/L/AC was best fit in Freundlich model with R2 of 0.96 and 0.97, respectively, which indicated the multilayer adsorption. In the Co(II) adsorption, the data was highly fit in Langmuir model with R2 of 0.94 and 0.92 which indicated the monolayer adsorption. These results indicated both materials exhibited chemisorption. The activation energy of Ze/L/AC in MB adsorption (34.9 kJ mol-1) was higher than that of Ze/L/AC in Co (II) adsorption (26 kJ mol-1).

Gold Nanoparticles AuNP Decorated on Fused Graphene-like Materials for Application in a Hydrogen Generation.

The search for a sustainable, alternative fuel source to replace fossil fuels has led to an increased interest in hydrogen fuel. This combustible gas is not only clean-burning but can readily be produced via the hydrolysis of sodium borohydride. The main drawback of this reaction is that the reaction occurs relatively slowly and requires a catalyst to improve efficiency. This study explored a novel composite material made by combining gold nanoparticles and fused graphene-like materials (AuFGLM) as a catalyst for generating hydrogen via sodium borohydride. The novel fused graphene-like material (FGLM) was made with a sustainable dextrose solution and by using a pressure-processing method. Imaging techniques showed that FGLM appears to be an effective support template for nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize and determine the size, shape, and structure of nanoparticles and composites. The TEM study characterized the fused carbon backbone as it began to take on a rounder shape. The TEM images also revealed that the average diameter of the gold nanoparticle was roughly 23 nm. The FTIR study confirmed O-H, C-C, and C=O as functional groups in the materials. The EDS analysis showed that the composite contained approximately 6.3% gold by weight. The crystal structures of FGLM and AuFGLM were identified via P-XRD analysis. Various reaction conditions were used to test the catalytic ability of AuFGLM, including various solution pHs, temperatures, and doses of NaBH4. It was observed that optimal reaction conditions included high temperature, an acidic solution pH, and a higher dose of NaBH4. The activation energy of the reaction was determined to be 45.5 kJ mol-1, and it was found that the catalyst could be used multiple times in a row with an increased volume of hydrogen produced in ensuing trials. The activation energy of this novel catalyst is competitive compared to similar catalysts and its ability to produce hydrogen over multiple uses makes the material an exciting choice for catalyzing the hydrolysis of NaBH4 for use as a hydrogen fuel source.

Synthesis of Platinum Nanoparticles Supported on Fused Nanosized Carbon Spheres Derived from Sustainable Source for Application in a Hydrogen Generation Reaction.

The dwindling supply of fossil fuels has prompted the search for an alternative energy source that could effectively replace them. Potential renewable energy sources such as solar, wind, tidal, and geothermal are all promising but each has its own drawbacks. Hydrogen gas on the other hand can be combusted to produce energy with only water as a byproduct and can be steadily generated via the aqueous media hydrolysis reaction of Sodium Borohydride (NaBH4). This study successfully synthesized fused carbon spheres derived from sugar and decorated them with platinum nanoparticles to form a novel composite material (PtFCS) for catalyzing this reaction. The platinum nanoparticles were produced by reducing chloroplatinic acid in a solution with sodium borohydride and using sodium citrate as a capping agent for the nanoparticles. Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterize and determine the size and shape of the Pt nanoparticles (PtNPs) and fused carbon spheres. TEM was able to determine the average size of the fused carbon spheres to be 200 nm and the average size for the PtNPs to be 2-3 nm. The PtFCS composite was tested for its ability to catalyze the hydrolysis of NaBH4 under various reaction conditions including various solution pH, various temperatures, and various dosages of sodium borohydride. The catalyst was found to perform the best under acidic solution conditions (pH 6), producing hydrogen at a rate of 0.0438 mL/mgcat·min. The catalyst was determined to have an activation energy of 53.0 kJ/mol and could be used multiple times in succession with no loss in the volume of hydrogen produced. This sugar-derived composite catalyst shows promise and could be implemented as a sustainable catalyst for the generation of hydrogen fuel.

Efficient Removal of Lead Ions from Aqueous Media Using Sustainable Sources Based on Marine Algae.

The goal of this project is to explore a new method to efficiently remove Pb(II) ions from water by processing Undaria pinnatifida into immobilized beads using sodium alginate and calcium chloride. The resulting biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Using immobilized U. pinnatifida, we investigated the effect of various factors on Pb(II) ion removal efficiency such as temperature, pH, ionic strength, time, and underlying biosorption mechanisms. For Pb(II) ion biosorption studies, Pb(II) ion biosorption data were obtained and analyzed using Langmuir and Freundlich adsorption models. It is found that the maximum Pb(II) ion adsorption capacity (X m) of U. pinnatifida was estimated to be ∼5 times greater than that of activated carbon, indicating the superior Pb(II) ion removal capability of U. pinnatifida compared to activated carbon. In addition, a thermodynamic study indicates that biosorption processes are found to be endothermic and an increase in the Pb(II) ion solution temperature provides a more preferential reaction toward Pb(II) ion biosorption.

Silver Nanoparticles Functionalized Nanosilica Grown over Graphene Oxide for Enhancing Antibacterial Effect.

The continuous growth of multidrug-resistant bacteria due to the overuse of antibiotics and antibacterial agents poses a threat to human health. Silver nanoparticles, silica-based materials, and graphene-based materials have become potential antibacterial candidates. In this study, we developed an effective method of enhancing the antibacterial property of graphene oxide (GO) by growing nanosilica (NS) of approximately 50 nm on the graphene oxide (GO) surface. The structures and compositions of the materials were characterized through powdered X-ray diffraction (P-XRD), transmission electron microscopy (TEM), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), ultraviolet-visible spectroscopy (UV-VIS), dynamic light scattering (DLS), Raman spectroscopy (RM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmet-Teller (BET) surface area, and pore size determination. The silver nanoparticles (AgNPs) with an average diameter of 26 nm were functionalized on the nanosilica (NS) surface. The composite contained approximately 3% of silver nanoparticles. The silver nanoparticles on nanosilica supported over graphene oxide (GO/NS/AgNPs) exhibited a 7-log reduction of Escherichia coli and a 5.2-log reduction of Bacillus subtilis within one hour of exposure. Both GO/NS and GO/NS/AgNPs exhibited substantial antimicrobial effects against E. coli and B. subtilis.

Organo-Nanocups Assist the Formation of Ultra-Small Palladium Nanoparticle Catalysts for Hydrogen Evolution Reaction.

Ultra-small palladium nanoparticles were synthesized and applied as catalysts for a hydrogen evolution reaction. The palladium metal precursor was produced via beta-cyclodextrin as organo-nanocup (ONC) capping agent to produce ultra-small nanoparticles used in this study. The produced ~3 nm nanoparticle catalyst was then characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared spectroscopy (FTIR) to confirm the successful synthesis of ~3 nm palladium nanoparticles. The nanoparticles' catalytic ability was explored via the hydrolysis reaction of sodium borohydride. The palladium nanoparticle catalyst performed best at 303 K at a pH of 7 with 925 µmol of sodium borohydride having an H2 generation rate of 1.431 mL min-1 mLcat-1. The activation energy of the palladium catalyst was calculated to be 58.9 kJ/mol.

Comparison of Electropolishing of Aluminum in a Deep Eutectic Medium and Acidic Electrolyte.

Research advances in electropolishing, with respect to the field of metalworking, have afforded significant improvements in the surface roughness and conductivity properties of aluminum polished surfaces in ways that machine polishing and simple chemical polishing cannot. The effects of a deep eutectic medium as an acid-free electrolyte were tested to determine the potential energy thresholds during electropolishing treatments based upon temperature, experiment duration, current, and voltage. Using voltammetry and chronoamperometry tests during electropolishing to supplement representative recordings via atomic force microscopy (AFM), surface morphology comparisons were performed regarding the electropolishing efficiency of phosphoric acid and acid-free ionic liquid treatments for aluminum. This eco-friendly solution produced polished surfaces superior to those surfaces treated with industry standard acid electrochemistry treatments of 1 M phosphoric acid. The roughness average of the as-received sample became 6.11 times smoother, improving from 159 nm to 26 nm when electropolished with the deep eutectic solvent. This result was accompanied by a mass loss of 0.039 g and a 7.2 µm change in step height along the edge of the electropolishing interface, whereas the acid treatment resulted in a slight improvement in surface roughness, becoming 1.63 times smoother with an average post-electropolishing roughness of 97.7 nm, yielding a mass loss of 0.0458 g and a step height of 8.1 µm.

A novel nanocomposite of Liquidambar styraciflua fruit biochar-crosslinked-nanosilica for uranyl removal from water.

Biochar adsorption has been protruded as a sustainable green and economic process for water remediation. This technology is facing high challenges in removing different pollutants, owning to the stable chemical and physical features of biochar. Therefore, a novel nanocomposite of Liquidambar styraciflua fruit biochar-crosslinked-nanosilica (BC-Gl-NSi) was synthesized and characterized (surface area = 60.754 m2 g-1 and particle size = 17.32-36.25 nm). The designed BC-Gl-NSi nanocomposite was explored for removal of uranyl ions by the batch adsorption technique under the influence of different factors including temperature, contact time, nanocomposite dosage, pH, uranyl ion concentration as well as co-existing ions. The adsorption process was principally confirmed to rely on the solution pH and reached 86.3% in pH 4.0. The results showed also that one-minute contact duration was sufficient to reach the maximum extraction of uranyl (30.0 mg L-1). Besides, [BC-Gl-NSi] exhibited excellent selectivity and good recovery of uranyl ions with other competing ions.

Synthesis of Cerium-Doped Titania Nanoparticles and Nanotubes.

Cerium-doped titania nanoparticles and nanotubes were synthesized via hydrothermal processes. X-Ray Diffraction revealed that cerium-doped titania nanoparticles have an anatase crystal structure, while cerium-doped titania nanotubes have an H2Ti3O7-type structure. Scanning electron microscopy and high resolution transmission electron microscopy showed that both types of titania are well crystallized with relatively uniform size distribution. The photocatalytic degradation of methylthioninium chloride known as methylene blue dye was tested and both cerium-doped titania nanoparticles and nanotubes. The preliminary photocatalytic degradation of Methylene Blue data showed significantly improved visible light photocatalytic activities as compared to commercial titania powders.

A novel cellulose-dioctyl phthate-baker's yeast biosorbent for removal of Co(II), Cu(II), Cd(II), Hg(II) and Pb(II).

In this work, dioctyl phthalate (Dop) was used as a highly plasticizing material to coat and link the surface of basic cellulose (Cel) with baker's yeast for the formation of a novel modified cellulose biosorbent (Cel-Dop-Yst). Characterization was accomplished by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA) and Scanning Electron Microscope (SEM) measurements. The feasibility of using Cel-Dop-Yst biosorbent as an efficient material for removal of Co(II), Cu(II), Cd(II), Hg(II) and Pb(II) ions was explored using the batch equilibrium technique along with various experimental controlling parameters. The optimum pH values for removal of these metal ions were characterized in the range of 5.0-7.0. Cel-Dop-Yst was identified as a highly selective biosorbent for removal of the selected divalent metal ions. The Cel-Dop-Yst biosorbent was successfully implemented in treatment and removal of these divalent metal ions from industrial wastewater, sea water and drinking water samples using a multistage microcolumn technique.

Magnetically active biosorbent for chromium species removal from aqueous media.

A magnetically active composite as adsorbent was synthesized via a facile in situ one-pot impregnation of magnetic nano-iron oxide (Fe3O4) on the surface of activated carbon (AC) for the formation of AC-Fe3O4. Baker(')s yeast was physically loaded on the resultant adsorbent AC-Fe3O4 to form a novel yeast coated magnetic composite AC-Fe3O4-Yst as biosorbent. The two synthesized adsorbents were characterized by using a scanning electron microscope (SEM) and assessed using Langmuir, the Brunauer-Emmet-Teller (BET) and Dubinin-Radushkevich (D-R) isotherm models. The validity and applicability of these two sorbents in adsorptive removal of chromium species, Cr(VI) and Cr(III), from aqueous solutions under the effect of a magnetic field were studied and evaluated in the presence of various controlling parameters in order to identify the optimal pH, contact time, mass dose and chromium concentrations for such adsorption process. Also, single and multi-stage micro-column techniques were used to study the potential applications of AC-Fe3O4 as magnetically active adsorbents and AC-Fe3O4-Yst as magnetically active biosorbents, for the removal of chromium species from various real water samples.

In vitro stability study of organophosphonic self assembled monolayers (SAMs) on cobalt chromium (Co-Cr) alloy.

Surface modification of cobalt chromium (Co-Cr) alloy is being investigated as a possible solution to the biomedical challenges arising from its usage. Self assembled monolayers (SAMs) of organophosphonic octadecylphosphonic acid (ODPA) were formed on the oxide surface of Co-Cr alloy by chemisorption using the solution deposition technique. High quality and well-ordered SAMs were formed which were characterized using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle measurements and ellipsometry. The resulting monolayers were then exposed to in vitro conditions using phosphate buffered saline (PBS) solution. The samples were analyzed for a period of 1, 3, 7 and 14 days. The resulting samples were characterized using XPS, AFM and Contact angle measurements. XPS atomic concentrations and detailed high energy elemental scans gave an insight into the trends of elemental concentrations over the duration of the study. SAMs were found to be strongly bound to the oxide surface after PBS exposure. AFM gave the topographic details of SAMs presence by island formation before and after SAM formation and also over the duration of the PBS exposure. Contact Angle Measurements confirmed the hydrophobicity of the surface after SAM formation and indicated a slight disorder of the SAM alkyl chain upon exposure to PBS. Thus, ODPA SAMs were successfully coated on Cobalt Chromium (Co-Cr) alloy surface and were found to be stable and strongly bound after PBS exposure.

Enhanced removal of lead by chemically and biologically treated carbonaceous materials.

Hybrid sorbents and biosorbents were synthesized via chemical and biological treatment of active carbon by simple and direct redox reaction followed by surface loading of baker's yeast. Surface functionality and morphology of chemically and biologically modified sorbents and biosorbents were studied by Fourier Transform Infrared analysis and scanning electron microscope imaging. Hybrid carbonaceous sorbents and biosorbents were characterized by excellent efficiency and superiority toward lead(II) sorption compared to blank active carbon providing a maximum sorption capacity of lead(II) ion as 500 µmol g(-1). Sorption processes of lead(II) by these hybrid materials were investigated under the influence of several controlling parameters such as pH, contact time, mass of sorbent and biosorbent, lead(II) concentration, and foreign ions. Lead(II) sorption mechanisms were found to obey the Langmuir and BET isotherm models. The potential applications of chemically and biologically modified-active carbonaceous materials for removal and extraction of lead from real water matrices were also studied via a double-stage microcolumn technique. The results of this study were found to denote to superior recovery values of lead (95.0-99.0 ± 3.0-5.0%) by various carbonaceous-modified-bakers yeast biosorbents.

Probing nanoparticle interactions in cell culture media.

Nanoparticle research is often performed in vitro with little emphasis on the potential role of cell culture medium. In this study, gold nanoparticle interactions with cell culture medium and two cancer cell lines (human T-cell leukemia Jurkat and human pancreatic carcinoma PANC1) were investigated. Gold nanoparticles of 10, 25, 50, and 100 nm in diameter at fixed mass concentration were tested. Size distributions and zeta potentials of gold nanoparticles suspended in deionized (DI) water and Dulbecco's Modified Eagle's Media (DMEM) supplemented with fetal calf serum (FCS) were measured using dynamic light scattering (DLS) technique. In DI water, particle size distributions exhibited peaks around their nominal diameters. However, the gold nanoparticles suspended in DMEM supplemented with FCS formed complexes around 100 nm, regardless of their nominal sizes. The DLS and UV-vis spectroscopy results indicate gold nanoparticle agglomeration in DMEM that is not supplemented by FCS. The zeta potential results indicate that protein rich FCS increases the dispersion quality of gold nanoparticle suspensions through steric effects. Cellular uptake of 25 and 50 nm gold nanoparticles by Jurkat and PANC1 cell lines were investigated using inductively coupled plasma-mass spectroscopy. The intracellular gold level of PANC1 cells was higher than that of Jurkat cells, where 50 nm particles enter cells at faster rates than the 25 nm particles.

Chemically and biologically modified activated carbon sorbents for the removal of lead ions from aqueous media.

A method is described for hybridization of the adsorption and biosorption characteristics of chemically treated commercial activated carbon and baker's yeast, respectively, for the formation of environmental friendly multifunctional sorbents. Activated carbon was loaded with baker's yeast after acid-base treatment. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to characterize these sorbents. Moreover, the sorption capabilities for lead (II) ions were evaluated. A value of 90 µmol g(-1) was identified as the maximum sorption capacity of activated carbon. Acid-base treatment of activated carbon was found to double the sorption capacity (140-180 µmol g(-1)). Immobilization of baker's yeast on the surface of activated carbon sorbents was found to further improve the sorption capacity efficiency of lead to 360, 510 and 560 µmol g(-1), respectively. Several important factors such as pH, contact time, sorbent dose, lead concentration and interfering ions were examined. Lead sorption process was studied and evaluated by several adsorption isotherms and found to follow the Langmuir and BET models. The potential applications of various chemically and biologically modified sorbents and biosorbents for removal of lead from real water matrices were also investigated via multistage micro-column technique and the results referred to excellent recovery values of lead (95.0-99.0 ± 3.0-5.0 %).

Stability of Phosphonic Self Assembled Monolayers (SAMs) on Cobalt Chromium (Co-Cr) Alloy under Oxidative conditions.

Cobalt Chromium (Co-Cr) alloys has been widely used in the biomedical arena for cardiovascular, orthopedic and dental applications. Surface modification of the alloy allows us to tailor the interfacial properties to address critical challenges of Co-Cr alloy in medical applications. Self assembled monolayers (SAMs) of Octadecylphosphonic acid (ODPA) have been used to form thin films on the oxide layer of the Co-Cr alloy surface by solution deposition technique. The SAMs formed were investigated for their stability to oxidative conditions of ambient laboratory environment over periods of 1, 3, 7 and 14 days. The samples were then characterized for their stability using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Contact Angle Measurements. Detailed high energy XPS elemental scans confirmed the presence of the phosphonic monolayer after oxidative exposure which suggested that the SAMs were firmly attached to the oxide layer of Co-Cr alloy. AFM images gave topographical data of the surface and showed islands of SAMs on Co-Cr alloy surface, before and after SAM formation and also over the duration of the oxidative exposure. Contact angle measurements confirmed the hydrophobicity of the surface over 14 days. Thus the SAMs were found to be stable for the duration of the study. These SAMs could be subsequently tailored by modifying the terminal functional groups and could be used for various potential biomedical applications such as drug delivery, biocompatibility and tissue integration.

Nanosecond pulse electrical fields used in conjunction with multi-wall carbon nanotubes as a potential tumor treatment.

The objectives of this communication were to fabricate pure samples of multi-walled carbon nanotubes (MWCNTs) and to determine their toxicity in tumor cell lines. MWCNTs were dispersed in a concentration of the surfactant T80 that was minimally toxic. Cell-type variation in toxicity to MWCNTs was observed but was not significantly different to unexposed controls. Additionally, we investigated the increased cell killing of the pancreatic cancer cell line PANC1 when exposed to ultrashort (nanosecond) pulsed electrical fields (nsPEF) in the presence of MWCNTs as a potential form of cancer therapy. We hypothesized that the unique electronic properties of MWCNTs disrupt cell function, leading to cell death, when cells are exposed to nsPEF. We observed a 2.3-fold reduction in cell survival in cells pulsed in the presence of MWCNTs compared to pulsed controls. This study demonstrates that ultrashort pulse electrical field applications have enhanced killing effects when cells are previously grown in the presence of MWCNTs, suggesting that the electrical properties of MWCNTs play a vital role in this process and is suggestive of a synergistic interaction between these nanomaterials and electrical fields.

Nanosized controlled surface pretreatment of biometallic alloy 316L stainless steel.

Stainless steel (AISI 316L) is a medical grade stainless steel alloy used extensively in medical devices and in the biomedical field. 316L stainless steel was successfully electropolished via an ecologically friendly and biocompatible ionic liquid (IL) medium based on Vitamin B4 (NB4) and resulting in nanosized surface roughness and topography. Voltammetry and chronoamperometry tests determined optimum polishing conditions for the stainless steel alloy while atomic force microscopy (AFM) and scanning electron microscopy (SEM) provided surface morphology comparisons to benchmark success of each electropolishing condition. Energy dispersive X-ray analysis (EDX) combined with SEM revealed significantly smoother surfaces for each alloy surface while indicating that the constituent metals comprising each alloy effectively electropolished at uniform rates.

Copper cation removal in an electrokinetic cell containing zeolite.

Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers.

Localized nanoscopic surface measurements of nickel-modified mica for single-molecule DNA sequence sampling.

Cleaved, cation-derivatized Muscovite mica is utilized extensively in atomic force microscopy (AFM) imaging because of its flatness over large areas (millimeter cleavage planes with local root-mean-square roughness < 0.3 nm), ease of preparation, and ability to adsorb charged biomolecules such as DNA (work by Hansma and Laney, Guthold et al., and McMaster et al.). In particular, NiCl(2) treatment has become a common method for controlling DNA adsorption on mica substrates while retaining the mica's ultraflat surface (work by Pietrement et al.). While several studies have modeled the mica/metal ion/DNA system using macroscopic colloidal theory (DLVO, etc.; Pietrement et al., Sushko et al., Pastre et al., and Cheng et al.), nickel/mica's physicochemical properties have not been well characterized on the nanoscale. Efforts to manipulate and engineer DNA nanostructures would benefit greatly from a better understanding of the surface chemistry of nickel/mica. Here we present in situ nanometer- and attogram-scale measurements and thermodynamic simulation results that show that the surface chemistry of nickel-treated mica is more complex than generally appreciated by AFM practitioners because of metal-ion speciation effects present at neutral pH. We also show that, under certain preparations, nickel/mica allows in situ nanoscopic nucleotide sequence mapping within individual surface-adsorbed DNA molecules by permitting localized, controlled desorption of the double helix by soluble DNA binding enzymes. These results should aid efforts to precisely control the DNA/mica binding affinity, particularly at the physiological pH ranges required by enzymatic biochemistry (pH 7.0-8.5), and facilitate the development of more complex and useful biochemical manipulations of adsorbed DNA, such as single-molecule sequencing.