Grafting of poly (ethylene glycol) (PEG) on the surface of polysulfone (PSF) sheets by simultaneous or sequential UV irradiation with 4-azidobenzoic acid as the photocoupler was carried out. Water contact angle measurements showed that there was a great improvement of hydrophilicity on the grafted surface. X-ray photoelectron spectroscopy suggested that the area covered by PEG be 77.3% and 41.9% respectively after grafting by simultaneous and sequential pathways. With atomic force microscope (AFM), obvious difference in the shape and the phase mode was observed between surfaces of PEG-g-PSF sheets made by these two pathways. Evidences implied that simultaneous pathway would produce a branched PEG layer on the surface, while sequential pathway was coupled with a "pan-cake" PEG layer on it. This study provides the foundation for further advancement in tethering brush-like PEG on PSF hollow fiber membranes.
Azides ; chemistry ; Biocompatible Materials ; chemistry ; Coated Materials, Biocompatible ; chemistry ; Membranes, Artificial ; Microscopy, Atomic Force ; Polyethylene Glycols ; chemistry ; Polymers ; chemistry ; Sulfones ; chemistry ; Ultraviolet Rays

BACKGROUND: Conventional acid-fast bacilli (AFB) staining cannot differentiate viable from dead cells. Propidium monoazide (PMA) is a photoreactive DNA-binding dye that inhibits PCR amplification by DNA modification. We evaluated whether PMA real-time PCR is suitable for the early detection of viable Mycobacterium tuberculosis (MTB) in clinical respiratory specimens. METHODS: A total of 15 diluted suspensions from 5 clinical MTB isolates were quadruplicated and subjected to PMA treatment and/or heat inactivation. Eighty-three AFB-positive sputum samples were also tested to compare the DeltaC(T) values (C(T) value in PMA-treated sputum samples-C(T) value in non-PMA-treated sputum samples) between culture-positive and culture-negative specimens. Real-time PCR was performed using Anyplex MTB/NTM Real-Time Detection (Seegene, Korea), and the C(T) value changes after PMA treatment were compared between culture-positive and culture-negative groups. RESULTS: In MTB suspensions, the increase in the C(T) value after PMA treatment was significant in dead cells (P=0.0001) but not in live cells (P=0.1070). In 14 culture-negative sputum samples, the median DeltaC(T) value was 5.3 (95% confidence interval [CI], 4.1-8.2; P<0.0001), whereas that in 69 culture-positive sputum samples was 1.1 (95% CI, 0.7-2.0). In the ROC curve analysis, the cutoff DeltaC(T) value for maximum sensitivity (89.9%) and specificity (85.7%) for differentiating dead from live cells was 3.4. CONCLUSIONS: PMA real-time PCR is a useful approach for differentiating dead from live bacilli in AFB smear-positive sputum samples.
Adult ; Aged ; Area Under Curve ; Azides/*chemistry ; DNA, Bacterial/*analysis ; Female ; Humans ; Lung Diseases/diagnosis/*microbiology/pathology ; Male ; Middle Aged ; Mycobacterium tuberculosis/genetics/*isolation & purification ; Pilot Projects ; Propidium/*analogs & derivatives/chemistry ; ROC Curve ; *Real-Time Polymerase Chain Reaction ; Sputum/microbiology ; Tuberculosis/*diagnosis/microbiology