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Volumn 17, Issue 12, 2002, Pages 3741-3748

Loading-rate dependence of individual ligand-receptor bond-rupture forces studied by atomic force microscopy

Author keywords

[No Author keywords available]

Indexed keywords

DYNAMIC FORCE SPECTRA; LOADING-RATE DEPENDENCE;

EID: 0037067292     PISSN: 07437463     EISSN: None     Source Type: Journal    
DOI: 10.1021/la001569g     Document Type: Article
Times cited : (120)

References (61)
  • 20
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    • Bell, G.I. Science 1978, 200, 618-627.
    • (1978) Science , vol.200 , pp. 618-627
    • Bell, G.I.1
  • 38
    • 0011286966 scopus 로고    scopus 로고
    • Park Scientific Instruments and TopoMetrix have merged to form ThermoMicroscopes
    • Park Scientific Instruments and TopoMetrix have merged to form ThermoMicroscopes.
  • 39
    • 0011292017 scopus 로고    scopus 로고
    • note
    • The noise level was estimated from the standard deviation of the flat portions of sampled force-distance curves before jump-in during the advancing process and after pull-off during the retracting process. Sources of noise that affect the force sensitivity of the instrument include thermal and mechanical vibrations and intensity fluctuations of the laser used in the optical detection system.
  • 41
    • 0011369199 scopus 로고    scopus 로고
    • note
    • At a scan velocity lower than 1 μm/s, it would take seconds to collect a single force-distance curve and a few minutes to obtain a set of multiple force curves. A considerable amount of thermal drift can take place during this time scale. This may be disadvantageous to the application of the Poisson analysis, which requires multiple measurements of one set to be conducted within a fixed contact area. The applicability of the Poisson analysis method at low loading rates will be examined in a future study.
  • 42
    • 0011287790 scopus 로고    scopus 로고
    • note
    • 5 points/ s)] = 200 μm/s, no matter how high the selected scan speed is. Being able to select very high apparent scan rates is a bug in the software, according to the manufacturer. We believe it is important to point this out so that researchers in the AFM community are aware of this potential problem, especially when carrying out studies at high scan speeds. To calibrate the tip scan velocity, a 100 Hz sine wave was externally input to the A/D channel as a clock to measure the time a tip traveled through various distances. It was confirmed that the number of data points on the curve determined the amount of time the tip scanned through a given distance. The scan velocity was then determined by the ratio of the distance and the travel time. The sine wave served as an accurate time stamp.
  • 43
    • 0011376559 scopus 로고    scopus 로고
    • note
    • Although the distribution is strictly binomial, with a low probability for the occurrence of a given event (i.e., bond formation), it can be approximated by Poisson statistics. A computer modeling study in our group has shown the Poisson model to be robust and generally applicable as long as bond-formation probabilities are low. In biological systems, factors such as steric hindrance and direction of approach can play a significant role in the interactions between biomolecules. Thus, it is a reasonable assumption that the bond-formation probability is low for most biological interactions between a functionalized tip and substrate.
  • 49
    • 0011360569 scopus 로고    scopus 로고
    • note
    • 3S, MW = 244.3) per mole of bovine serum albumin (MW ≈ 67 kDa) in the BBSA used in this study. The amount of biotin in BBSA is less than 5% in mass, which makes it difficult to probe molecular fragments of biotin by TOF-SIMS, especially amid the complexity of other peaks from protein fragments.
  • 54
    • 0011369201 scopus 로고    scopus 로고
    • note
    • The presence of multiple steps in the retracting F/S curve has been observed by us and others in several biological systems and is generally attributed to sequential breaking of interacting bonds. The possibility of contact between the AFM tip and the substrate should be low due to the following reasons: (1) The nature of the interactions between the AFM tip and the substrate (protein-glass) is very different from that of the ligand-receptor interactions. The former is expected to be stronger in magnitude than the latter. Thus, they should be well differentiated in the F/S curves if both are present. (2) In our study, surface modification was done via noncovalent adsorption of a biotinylated "glue" protein BSA. If the tip penetrated through the BBSA layer and contacted the glass substrate, it could result in irreproducible F/S curves in subsequent pull-off events due to desorption or damage to the protein films. None of the above were observed in our systems, so we believe that the multiple pull-offs in our F/S curves were mainly due to the sequential breaking of multiple tip-surface bonds.
  • 56
    • 0011367130 scopus 로고
    • Blauer, G., Sund, H., Eds.; Walter de Gruyter & Co.: New York
    • Peters, T., Jr.; Reed, R.G. In Transport by Proteins; Blauer, G., Sund, H., Eds.; Walter de Gruyter & Co.: New York, 1978.
    • (1978) Transport by Proteins
    • Peters T., Jr.1    Reed, R.G.2
  • 61
    • 0011376560 scopus 로고    scopus 로고
    • note
    • L ("rigid BSA"), g ≃ 0.1.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.