scholarly journals Study of a Model Humic Acid-type Polymer by Fluorescence Spectroscopy and Atomic Force Microscopy

2012 ◽  
Vol 03 (07) ◽  
pp. 478-484
Author(s):  
Marcilene Ferrari Barriquello ◽  
Fábio de Lima Leite ◽  
Daiana Kotra Deda ◽  
Sérgio da Costa Saab ◽  
Nelson Consolin-Filho ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Fluorescence Spectroscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Acid Type

Probing molecular interactions between humic acid and surface-grafted polyacrylamide using quartz crystal microbalance with dissipation and atomic force microscopy: implications for environmental remediation

2018 ◽  
Vol 15 (6) ◽  
pp. 336 ◽  
Author(s):  
Omar Maan ◽  
Jun Huang ◽  
Hongbo Zeng ◽  
Qingye Lu
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Quartz Crystal Microbalance ◽  
Molecular Interactions ◽  
Environmental Remediation ◽  
Quartz Crystal ◽  
Major Constituent ◽  
Environmental Behaviour ◽  
Force Microscopy ◽  
Atomic Force

Environmental contextPolyacrylamide and its derivatives may enter the natural environment as a consequence of their wide use in various industrial applications. This study demonstrates the application of a quartz crystal microbalance and atomic force microscopy to study the molecular interactions between polyacrylamides and humic acids under various solution chemistries. The knowledge obtained can be used to understand and predict the environmental behaviour of polyacrylamides. AbstractA fundamental understanding of the environmental behaviour of polyacrylamide (PAM) is of importance for guiding environmental remediation. We create a framework for understanding the molecular interactions between PAM and a major constituent present in all natural waters and soil, humic acid (HA), using a quartz crystal microbalance with dissipation (QCM-D) and an atomic force microscope (AFM). A thin film of PAM was grafted on a silica surface silanised with 3-(trimethoxysilyl)propyl methacrylate and the resulting surface was characterised by X-ray photoelectron spectroscopy for the chemical bonds and composition, secondary ion mass spectrometry for the composition and molecular weight, water contact angle measurements for the hydrophilicity, AFM for the morphology, and ellipsometry for the thickness. Surface-grafted PAM was used to study its interactions with HA in aqueous solutions at different pH (2, 7, and 10) and NaCl salt concentrations (1, 10, and 100 mM, within the range of salt concentrations of fresh water) using QCM-D. QCM-D measurements showed that compared with bare silica, the adsorption of HA by PAM-coated silica was greatly reduced at all pHs and salt concentrations, and the adsorption of HA on PAM-coated silica depended on the solution chemistry including solution pH and salt concentration. Hydrogen bonding between PAM and HA is the major driving force for HA to adsorb on PAM. AFM force measurements showed that adhesion between PAM and HA was observed only at acidic conditions. The knowledge obtained from this study will benefit the prediction of the environmental behaviour of PAMs under different conditions in natural/engineered environments and provide guidance for the design of remediation technologies for water and soil.

scholarly journals DNA-Directed Assembly of Carbon Nanotube–Protein Hybrids

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 955
Author(s):  
Mark Freeley ◽  
Rebecca E. A. Gwyther ◽  
D. Dafydd Jones ◽  
Matteo Palma
Keyword(s):  
Atomic Force Microscopy ◽  
Carbon Nanotube ◽  
Fluorescence Spectroscopy ◽  
Emission Intensity ◽  
Directed Assembly ◽  
Electronic Coupling ◽  
Force Microscopy ◽  
Controlled Assembly ◽  
Atomic Force ◽  
Microscopy Images

Here, we report the controlled assembly of SWCNT–GFP hybrids employing DNA as a linker. Two distinct, enriched SWCNTs chiralities, (6,5), (7,6), and an unsorted SWCNT solution, were selectively functionalized with DNA and hybridized to a complementary GFPDNA conjugate. Atomic force microscopy images confirmed that GFP attachment occurred predominantly at the terminal ends of the nanotubes, as designed. The electronic coupling of the proteins to the nanotubes was confirmed via in-solution fluorescence spectroscopy, that revealed an increase in the emission intensity of GFP when linked to the CNTs.

scholarly journals Effect of Acidithiobacillus ferrooxidans on Humic-Acid Passivation Layer on Pyrite Surface

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 422 ◽  
Author(s):  
Hongying Yang ◽  
Wenjie Luo ◽  
Ying Gao
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Pyrite Oxidation ◽  
Passivation Layer ◽  
Pyrite Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Leaching Experiments ◽  
Bacterial Adsorption ◽  
Number Of Bacteria

The effect of Acidithiobacillus ferrooxidans on the humic-acid passivation layer on pyrite surfaces was studied by atomic-force microscopy, leaching experiments, and adsorption experiments. Atomic-force-microscopy results showed that humic-acid was adsorbed onto the pyrite surface. The bacteria grew and reproduced on the humic-acid layer. Leaching experiments showed that the humic-acid passivation layer prevented the oxidation of pyrite by Fe3+ under aseptic conditions. Bacteria destroyed the humic-acid layer, promoted pyrite oxidation, and increased the oxidation of pyrite from 1.64% to 67.9%. Bacterial adsorption experiments showed that the humic-acid passivation layer decreased the speed of bacterial adsorption on the pyrite surface but had no effect on the number of bacteria adsorbed on the pyrite surface. The maximum number of bacteria adsorbed by pyrite with and without the humic-acid layer was 4.17 × 1010 cells∙mL−1 and 4.4 × 1010 cells∙mL−1, respectively. Extracellular polymeric stratum layer of bacteria cultured at different concentrations of humic-acid was extracted and analyzed. This layer could destroy the humic-acid layer and promote pyrite oxidation.

Sign in / Sign up

Export Citation Format

Share Document