ABSTRACT
Plasmonic biosensing has emerged as the most sensitive label-free technique to detect various molecular species in solutions and has already proved crucial in drug discovery, food safety and studies of bio-reactions. This technique relies on surface plasmon resonances in ~50 nm metallic films and the possibility to functionalize the surface of the metal in order to achieve selectivity. At the same time, most metals corrode in bio-solutions, which reduces the quality factor and darkness of plasmonic resonances and thus the sensitivity. Furthermore, functionalization itself might have a detrimental effect on the quality of the surface, also reducing sensitivity. Here we demonstrate that the use of graphene and other layered materials for passivation and functionalization broadens the range of metals which can be used for plasmonic biosensing and increases the sensitivity by 3-4 orders of magnitude, as it guarantees stability of a metal in liquid and preserves the plasmonic resonances under biofunctionalization. We use this approach to detect low molecular weight HT-2 toxins (crucial for food safety), achieving phase sensitivity~0.5 fg/mL, three orders of magnitude higher than previously reported. This proves that layered materials provide a new platform for surface plasmon resonance biosensing, paving the way for compact biosensors for point of care testing.
ABSTRACT
Chronic postinfarction patients with an ejection fraction ≤ 30% and heart failure patients in NYHA classes II and III with an ejection fraction ≤ 35% due to ischemic or dilated cardiomyopathy meet current indications for ICD therapy. There is significant overlap with patients in NYHA class III also exhibiting a wide QRS complex (>120 ms), who commonly benefit from resynchronization therapy. Although a combination of ICD and CRT seems reasonable in many patients, one should be aware of subtle distinctions regarding selection criteria for either therapy. There is no clear ICD indication for heart failure patients in NYHA class IV or even III, taking subclass analysis of SCD-HeFT [4] into account. Uncertainty still exists for the subacute postinfarction phase (4 weeks to 6 months), whereas the early postinfarction phase should clearly not be considered for ICD evaluation. No randomized data exist for heart failure due to other etiologies. CRT, on the other hand, is not only helpful regarding symptom relief and quality of life, but also with respect to life expectancy. The additive value of adjunctive ICD therapy has not yet been proven in a randomized comparison. Finally, particularly in elderly patients, quality of life might seem more desirable than prevention of sudden cardiac death. Thus, combination of ICD and CRT is not always a "must". Instead, ICD guidelines still leave room for a patient specific decision, with "stand-alone" CRT still providing a very helpful, prognostically significant therapy.
