Plasmonic gratings with nano-protrusions made by glancing angle deposition for single-molecule super-resolution imaging

Super-resolution imaging has been advantageous in studying biological and chemical systems, but the required equipment and platforms are expensive and unable to observe single-molecules at the high (μM) fluorophore concentrations required to study protein interaction and enzymatic activity. Here, a plasmonic platform was designed that utilized an inexpensively fabricated plasmonic grating in combination with a scalable glancing angle deposition (GLAD) technique using physical vapor deposition. The GLAD creates an abundance of plasmonic nano-protrusion probes that combine the surface plasmon resonance (SPR) from the periodic gratings with the localized SPR of these nano-protrusions. The resulting platform enables simultaneous imaging of a large area without point-by-point scanning or bulk averaging for the detection of single Cyanine-5 molecules in dye concentrations ranging from 50 pM to 10 μM using epifluorescence microscopy. Combining the near-field plasmonic nano-protrusion probes and super-resolution technique using localization microscopy, we demonstrate the ability to resolve grain sizes down to 65 nm. This plasmonic GLAD grating is a cost-effective super-resolution imaging substrate with potential applications in high-speed biomedical imaging over a wide range of fluorescent concentrations.

Influence of silver grain size, roughness, and profile on the extraordinary fluorescence enhancement capabilities of grating coupled surface plasmon resonance

Silver gratings with different metal film properties and structures were examined to determine their effect on metal enhanced fluorescence.

Counting Single Rhodamine 6G Dye Molecules in Organosilicate Nanoparticles

Rhodamine 6G (R6G) dye molecules have been embedded into organosilicate nanoparticles to improve thermal and chemical stability of these marker molecules. We demonstrate that the well-established method of optical single-particle microscopy can be used to determine the number of dye molecules per nanoparticle in such hybrid materials. Analysing the fluorescence intensity of R6G in single nanoparticles, we obtain an average number of 1.3 - 1.7 dye molecules per nanoparticle as compared to 1 R6G per particle obtained from ensemble experiments. The blinking behaviour of embedded R6G can be described by a power law with an exponent α(on/off) = - 1.7. Ensemble measurements complete the optical characterization of the nanoparticles, which reveals no pronounced R6G aggregate formation.

Psychological distress in caretakers or relatives of patients with borderline personality disorder

BACKGROUND AND AIMS

Caregivers or relatives of mental patients often show increased levels of psychological distress. This study investigated whether this is also the case for caregivers of patients with borderline personality disorder.

METHODS

The Symptom Check List (SCL-90) was administered to 64 Dutch volunteers, who were either biologically related (parents or siblings) or biologically unrelated caregivers (partners or friends) of patients with borderline personality disorder.

RESULTS

The group of caregivers as a whole scored higher on all symptom dimensions of the SCL-90 than the general population. When controlling for caregiver sex and age, as well as for patient sex, there were no significant differences between the biologically related and unrelated caregiver groups on any dimension.

CONCLUSIONS

The results are in line with findings concerning distress in caregivers of patients suffering from personality disorders in general, posttraumatic stress disorder or schizophrenia. The mechanism behind the increased levels of distress in our sample is not clear, however. Either exposure to the problematic behaviour of the patient, selective mating or a combination of both might have been responsible for the effect.

Shading the truth in seeking informed consent for research purposes

I want to argue for two propositions. First, I suggest that what some researchers may take to be a simple trade-off between minor violations of the truth for the sake of access to far greater truths represents a profound miscalculation with far-reaching and cumulative reverberations. Second, I submit that today's research environment, as demanding, competitive, and sometimes bewildering as it is, offers genuine scope for what Murdoch calls truth-seeking, for imaging and questioning, and for relating to facts through both truth and truthfulness; but that, in so doing, it presents hard choices with respect to methods, and, in turn, to personal integrity--not only in particular research projects but also with respect to that fragile research environment in its own right.

Impaired physicians: what should patients know?

What should patients know about the degree to which their physicians may be impaired—unable, in the words of the American Medical Association (A.M.A.), “to practice medicine with reasonable skill and safety to patients by reason of physical or mental illness, including alcoholism and drug dependence”? What patients do in fact find out about such matters as alcohol or other drug abuse by, say, the surgeon or the anesthesiologist in charge of their care is another matter altogether; most patients learn about such impairment the hard way. But what should they know beforehand, if at all possible?

Testosterone metabolism in prepubertal rabbit cartilage

Using thin-layer chromatography, celite column chromatography and recrystallization methods, articular (AR) and growth plate (GP) cartilage tissues and cells from prepubertal rabbits were shown to convert testosterone (T) into at least three main metabolites: dihydrotestosterone (DHT), delta 4-androstenedione and androstanediols. In tissue incubation experiments the amount of each newly formed metabolite per mg of tissue was always greater in AR than in GP cartilage. After a 24 h incubation with AR or GP cartilage tissues, T was mainly converted to DHT and delta 4-androstenedione in approximately equal amounts. The amount of androstanediol metabolites formed was much lower. In a time-course experiment, the conversion of T to DHT and delta 4-androstenedione was shown to increase in a linear fashion, while the conversion to androstanediols was more variable. Using cultured AR cartilage cell incubations, similar results were obtained. In addition, DHT was shown to be the sole metabolite which accumulated in the cellular pool during the first 3 h incubation, as well as during the 24 h incubation when maximum cellular uptake of radioactivity was observed. At this time, the intracellular amount of unmetabolized [3H]T (88 pmoles/100 micrograms DNA) was similar to the amount of [3H]DHT (70 pmoles/100 micrograms DNA) accumulated in the chondrocytes. For both delta 4-androstenedione and androstanediols, 99% of radioactivity was extracted from the incubation medium.