Adsorption of Candida rugosa lipase onto alumina: Effect of surface charge

The impact of the surface charge of alumina support on the adsorption of Candida rugosa lipase has been investigated in terms of zeta potential of the adsorption partners. Lipase adhered onto alumina with similar efficiency under both repulsive and attractive electrostatic conditions, shifting the zeta potential of the support towards that of the enzyme. The behavior was explained by a heterogeneous distribution of the surface charge of the lipase molecule. Special emphasis in this study was placed on the effect of immobilization on enzyme kinetics and principal reasons for enzyme immobilization: improvement in stability and potential for reuse. The enzyme affinity was not altered by its adsorption onto alumina, while Vmax of the lipase decreased. Thermostability of adsorbed lipase was improved. Significant potential for reuse was found.

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The impact of zeta potential changes on Ceratium hirundinella cell removal and the ability of cells to restore its natural surface charge during drinking water purification

RSC Advances ◽

10.1039/c7ra01185g ◽

2017 ◽

Vol 7 (36) ◽

pp. 22433-22440 ◽

Cited By ~ 1

Author(s):

H. Ewerts ◽

S. Barnard ◽

A. Swanepoel

Keyword(s):

Drinking Water ◽

Zeta Potential ◽

Surface Charge ◽

Water Purification ◽

Settling Time ◽

Organic Polymer ◽

Source Water ◽

Ceratium Hirundinella ◽

Drinking Water Purification ◽

The Impact

The removal efficacy ofCeratiumcells from source water was evaluated. The best ZP for coagulation were achieved with organic polymer and Ca(OH)2. Cells were able to restore their ZP after 120 and 240 minutes settling time.

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Electroviscous effect on fluid drag in a microchannel with large zeta potential

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.6.226 ◽

2015 ◽

Vol 6 ◽

pp. 2207-2216 ◽

Cited By ~ 16

Author(s):

Dalei Jing ◽

Bharat Bhushan

Keyword(s):

Zeta Potential ◽

Surface Charge ◽

Electrical Potential ◽

Slip Condition ◽

Double Layers ◽

Electroviscous Effect ◽

Fluid Drag ◽

Pressure Driven Flow ◽

Effect Of Surface ◽

Pressure Driven

The electroviscous effect has been widely studied to investigate the effect of surface charge-induced electric double layers (EDL) on the pressure-driven flow in a micro/nano channel. EDL has been reported to reduce the velocity of fluid flow and increase the fluid drag. Nevertheless, the study on the combined effect of EDL with large zeta potential up to several hundred millivolts and surface charge depenedent-slip on the micro/nano flow is still needed. In this paper, the nonlinear Poisson–Boltzmann equation for electrical potential and ion distribution in non-overlapping EDL is first analytically solved. Then, the modified Navier–Stokes equation for the flow considering the effect of surface charge on the electrical conductivity of the electrolyte and slip length is analytically solved. This analysis is used to study the effect of non-overlapping EDL with large zeta potential on the pressure-driven flow in a microchannel with no-slip and charge-dependent slip conditions. The results show that the EDL leads to an increase in the fluid drag, but that slip can reduce the fluid drag. When the zeta potential is large enough, the electroviscous effect disappears for flow in the microchannel under a no-slip condition. However, the retardation of EDL on the flow and the enhancement of slip on the flow counteract each other under a slip condition. The underlying mechanisms of the effect of EDL with large zeta potential on fluid drag are the high net ionic concentration near the channel wall and the fast decay of electrical potential in the EDL when the zeta potential is large enough.

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Surface charge modulation of rifampicin-loaded PLA nanoparticles to improve antibiotic delivery in Staphylococcus aureus biofilms

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00760-w ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

David Da Costa ◽

Chloé Exbrayat-Héritier ◽

Basile Rambaud ◽

Simon Megy ◽

Raphaël Terreux ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Surface Charge ◽

Treatment Efficacy ◽

Particle Migration ◽

Bacterial Biofilm ◽

Poly Lactic Acid ◽

Retention Capacity ◽

The Impact ◽

Positively Charged ◽

Antibiotic Delivery

Abstract Background After the golden age of antibiotic discovery, bacterial infections still represent a major challenge for public health worldwide. The biofilm mode of growth is mostly responsible for chronic infections that current therapeutics fail to cure and it is well-established that novel strategies must be investigated. Particulate drug delivery systems are considered as a promising strategy to face issues related to antibiotic treatments in a biofilm context. Particularly, poly-lactic acid (PLA) nanoparticles present a great interest due to their ability to migrate into biofilms thanks to their submicronic size. However, questions still remain unresolved about their mode of action in biofilms depending on their surface properties. In the current study, we have investigated the impact of their surface charge, firstly on their behavior within a bacterial biofilm, and secondly on the antibiotic delivery and the treatment efficacy. Results Rifampicin-loaded PLA nanoparticles were synthetized by nanoprecipitation and characterized. A high and superficial loading of rifampicin, confirmed by an in silico simulation, enabled to deliver effective antibiotic doses with a two-phase release, appropriate for biofilm-associated treatments. These nanoparticles were functionalized with poly-l-lysine, a cationic peptide, by surface coating inducing charge reversal without altering the other physicochemical properties of these particles. Positively charged nanoparticles were able to interact stronger than negative ones with Staphylococcus aureus, under planktonic and biofilm modes of growth, leading to a slowed particle migration in the biofilm thickness and to an improved retention of these cationic particles in biofilms. While rifampicin was totally ineffective in biofilms after washing, the increased retention capacity of poly-l-lysine-coated rifampicin-loaded PLA nanoparticles has been associated with a better antibiotic efficacy than uncoated negatively charged ones. Conclusions Correlating the carrier retention capacity in biofilms with the treatment efficacy, positively charged rifampicin-loaded PLA nanoparticles are therefore proposed as an adapted and promising approach to improve antibiotic delivery in S. aureus biofilms.

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Candida rugosa Lipase-Mediated Enantioselective Acetylation Studies on (.+-.)-3-Arylmethyl-3-hydroxymethyl-2,3-dihydro-1-benzopyran-4(H)-ones.

ChemInform ◽

10.1002/chin.200523030 ◽

2005 ◽

Vol 36 (23) ◽

Author(s):

Smriti Trikha ◽

Rajesh Kumar ◽

Ashish Dhawan ◽

Poonam Poonam ◽

Ashok K. Prasad ◽

...

Keyword(s):

Candida Rugosa ◽

Candida Rugosa Lipase

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Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

Membranes ◽

10.3390/membranes11010025 ◽

2020 ◽

Vol 11 (1) ◽

pp. 25

Author(s):

Javed Alam ◽

Arun Kumar Shukla ◽

Mohammad Azam Ansari ◽

Fekri Abdulraqeb Ahmed Ali ◽

Mansour Alhoshan

Keyword(s):

Zeta Potential ◽

Surface Properties ◽

Antibacterial Activities ◽

Pani Film ◽

Force Microscopy ◽

Water Permeation ◽

Membrane Pores ◽

Membrane Performance ◽

Phenyl Sulfone ◽

The Impact

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (BR) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The BR values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

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EFFECTS OF POLYMERIC NANOPARTICLE SURFACE PROPERTIES ON INTERACTION WITH BRAIN TUMOR ENVIRONMENT

Nano LIFE ◽

10.1142/s1793984413430034 ◽

2013 ◽

Vol 03 (04) ◽

pp. 1343003 ◽

Cited By ~ 7

Author(s):

BRANDON MATTIX ◽

THOMAS MOORE ◽

OLGA UVAROV ◽

SAMUEL POLLARD ◽

LAUREN O'DONNELL ◽

...

Keyword(s):

Human Brain ◽

Surface Charge ◽

Cellular Uptake ◽

Drug Clearance ◽

Cellular Interaction ◽

Normal Tissues ◽

Poly Ethylene ◽

Uptake Studies ◽

Effect Of Surface

Current chemotherapy treatments are limited by poor drug solubility, rapid drug clearance and systemic side effects. Additionally, drug penetration into solid tumors is limited by physical diffusion barriers [e.g., extracellular matrix (ECM)]. Nanoparticle (NP) blood circulation half-life, biodistribution and ability to cross extracellular and cellular barriers will be dictated by NP composition, size, shape and surface functionality. Here, we investigated the effect of surface charge of poly(lactide)-poly(ethylene glycol) NPs on mediating cellular interaction. Polymeric NPs of equal sizes were used that had two different surface functionalities: negatively charged carboxyl ( COOH ) and neutral charged methoxy ( OCH 3). Cellular uptake studies showed significantly higher uptake in human brain cancer cells compared to noncancerous human brain cells, and negatively charged COOH NPs were uptaken more than neutral OCH 3 NPs in 2D culture. NPs were also able to load and control the release of paclitaxel (PTX) over 19 days. Toxicity studies in U-87 glioblastoma cells showed that PTX-loaded NPs were effective drug delivery vehicles. Effect of surface charge on NP interaction with the ECM was investigated using collagen in a 3D cellular uptake model, as collagen content varies with the type of cancer and the stage of the disease compared to normal tissues. Results demonstrated that NPs can effectively diffuse across an ECM barrier and into cells, but NP mobility is dictated by surface charge. In vivo biodistribution of OCH 3 NPs in intracranial tumor xenografts showed that NPs more easily accumulated in tumors with less collagen. These results indicate that a robust understanding of NP interaction with various tumor environments can lead to more effective patient-tailored therapies.

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