Highly Robust Interfacially Polymerized PA Layer on Thermally Responsive Semi-IPN Hydrogel: Toward On-Demand Tuning of Porosity and Surface Charge

2021 ◽  
Author(s):  
Nupur Gupta ◽  
Yen Nan Liang ◽  
Jia Wei Chew ◽  
Xiao Hu
Keyword(s):  
Surface Charge ◽  
On Demand ◽  
Thermally Responsive

scholarly journals Nanopore design for exceptional rectification of DNA translocation

2021 ◽  
Author(s):  
Ngan Pham ◽  
Yao Yao ◽  
Chenyu Wen ◽  
Shiyu Li ◽  
Shuangshuang Zeng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solid State ◽  
Surface Charge ◽  
Dna Translocation ◽  
Sensor Applications ◽  
Sensor Performance ◽  
On Demand ◽  
Dna Strands ◽  
Large Opening ◽  
Shape And Size

Abstract Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performance. However, reproducible production of arrayed nanopores of predefined geometry is yet to demonstrate despite of numerous methods explored. Here, bowl-shape SSNPs combining unique properties of ultrathin membrane and tapering geometry are demonstrated. The bowl-SSNP upper opening is 100-120 nm in diameter, with the bottom opening reaching sub-5 nm. Numerical simulation reveals the formation of multiple electroosmotic vortexes (EOVs) originating from distributed surface charge around the pore-bowl. The EOVs determine, collaboratively with electrophoretic force, how nanoscale objects translocate the bowl-SSNPs. Exceptional rectification with higher frequencies, longer duration and larger amplitude is found when DNA strands translocate downwards from the upper large opening than upwards from the bottom smallest restriction. The rectification is a manifestation of the interplay between electrophoresis and electroosmosis. The resourceful silicon nanofabrication technology is ingeniously shown to enable innovative nanopore designs targeting unprecedented sensor applications.

scholarly journals Development of Thermally Responsive PolyNIPAm Microcarrier for Application of Cell Culturing—Part I: A Feasibility Study

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2629
Author(s):  
Pui May Chou ◽  
Poi Sim Khiew ◽  
Paul D Brown ◽  
Binjie Hu
Keyword(s):  
Surface Charge ◽  
Cetyl Trimethyl Ammonium Bromide ◽  
Cell Attachment ◽  
Suspension Polymerization ◽  
Ammonium Persulfate ◽  
Ammonium Bromide ◽  
Thermally Responsive ◽  
Cell Culturing ◽  
Redox Initiator ◽  
Cetyl Trimethyl Ammonium

Poly(N-isopropylacrylamide) (polyNIPAm) microspheres were synthesized via the suspension polymerization technique. Thermal and redox initiators were compared for the polymerization, in order to study the effect of initiator type on the surface charge and particle size of polyNIPAm microspheres. The successful polymerization of NIPAm was confirmed by FTIR analysis. Microspheres of diameter >50 µm were synthesized when a pair of ammonium persulfate (APS) and N,N,N’,N’-tetramethylene-diamine (TEMED) redox initiators was used, whilst relatively small microspheres of ~1 µm diameter were produced using an Azobis-isobutyronitrile (AIBN) thermal initiator. Hence, suspension polymerization using a redox initiator pair was found to be more appropriate for the synthesis of polyNIPAm microspheres of a size suitable for human embryonic kidney (HEK) cell culturing. However, the zeta potential of polyNIPAm microspheres prepared using an APS/TEMED redox initiator was significantly more negative than AIBN thermal initiator prepared microspheres and acted to inhibit cell attachment. Conversely, strong cell attachment was observed in the case of polyNIPAm microspheres of diameter ~90 µm, prepared using an APS/TEMED redox initiator in the presence of a cetyl trimethyl ammonium bromide (CTAB) cationic surfactant; demonstrating that surface charge modified polyNIPAm microspheres have great potential for use in cell culturing.

scholarly journals On-demand pH-sensitive surface charge-switchable polymeric micelles for targeting Pseudomonas aeruginosa biofilms development

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Xiangjun Chen ◽  
Rong Guo ◽  
Changrong Wang ◽  
Keke Li ◽  
Xinyu Jiang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Surface Charge ◽  
Bacterial Resistance ◽  
Polymeric Micelles ◽  
Effective Means ◽  
Ph Sensitive ◽  
Bacterial Biofilm ◽  
Mice Model ◽  
On Demand

AbstractBacterial biofilm is the complicated clinical issues, which usually results in bacterial resistance and reduce the therapeutic efficacy of antibiotics. Although micelles have been drawn attention in treatment of the biofilms, the micelles effectively permeate and retain in biofilms still facing a big challenge. In this study, we fabricated on-demand pH-sensitive surface charge-switchable azithromycin (AZM)-encapsulated micelles (denoted as AZM-SCSMs), aiming to act as therapeutic agent for treating Pseudomonas aeruginosa (P. aeruginosa) biofilms. The AZM-SCSMs was composed of poly(l-lactide)-polyetherimide-hyd-methoxy polyethylene glycol (PLA-PEI-hyd-mPEG). It was noteworthy that the pH-sensitive acylhydrazone bond could be cleaved in acidic biofilm microenvironment, releasing the secondary AZM-loaded cationic micelles based on PLA-PEI (AZM-SCMs) without destroying the micellar integrity, which could tailor drug-bacterium interaction using micelles through electrostatic attraction. The results proved that positively charged AZM-SCMs could facilitate the enhanced penetration and retention inside biofilms, improved binding affinity with bacterial membrane, and added drug internalization, thus characterized as potential anti-biofilm agent. The excellent in vivo therapeutic performance of AZM-SCSMs was confirmed by the targeting delivery to the infected tissue and reduced bacterial burden in the abscess-bearing mice model. This study not only developed a novel method for construction non-depolymerized pH-sensitive SCSMs, but also provided an effective means for the treatment of biofilm-related infections.

scholarly journals Functionalizing Fibrin Hydrogels with Thermally Responsive Oligonucleotide Tethers for On-Demand Delivery

2022 ◽  
Vol 9 (1) ◽  
pp. 25
Author(s):  
Chase S. Linsley ◽  
Kevin Sung ◽  
Cameron White ◽  
Cara A. Abecunas ◽  
Bill J. Tawil ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Stimuli Responsive ◽  
On Demand ◽  
Thermally Responsive ◽  
Inhibitor Peptide ◽  
Model Drug ◽  
Plasmin Inhibitor ◽  
Incorporation Efficiency

There are a limited number of stimuli-responsive biomaterials that are capable of delivering customizable dosages of a therapeutic at a specific location and time. This is especially true in tissue engineering and regenerative medicine applications, where it may be desirable for the stimuli-responsive biomaterial to also serve as a scaffolding material. Therefore, the purpose of this study was to engineer a traditionally non-stimuli responsive scaffold biomaterial to be thermally responsive so it could be used for on-demand drug delivery applications. Fibrin hydrogels are frequently used for tissue engineering and regenerative medicine applications, and they were functionalized with thermally labile oligonucleotide tethers using peptides from substrates for factor XIII (FXIII). The alpha 2-plasmin inhibitor peptide had the greatest incorporation efficiency out of the FXIII substrate peptides studied, and conjugates of the peptide and oligonucleotide tethers were successfully incorporated into fibrin hydrogels via enzymatic activity. Single-strand complement oligo with either a fluorophore model drug or platelet-derived growth factor-BB (PDGF-BB) could be released on demand via temperature increases. These results demonstrate a strategy that can be used to functionalize traditionally non-stimuli responsive biomaterials suitable for on-demand drug delivery systems (DDS).

Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

1991 ◽  
Vol 49 ◽  
pp. 376-377 ◽  
Author(s):  
N.J. Tao ◽  
J.A. DeRose ◽  
P.I. Oden ◽  
S.M. Lindsay
Keyword(s):  
Surface Charge ◽  
Environmental Effects ◽  
Scanning Probe Microscopy ◽  
Statistical Significance ◽  
Electrochemical Methods ◽  
Surface Structures ◽  
Scanning Probe ◽  
Potential Control ◽  
Afm Imaging ◽  
Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

Psychology 101, on demand

2008 ◽  
Author(s):  
Jamie Chamberlin
Keyword(s):  
On Demand
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