1,721,061 research outputs found
Really biomimetic: A synthetic hydrolase matching the proficiency of enzymes
No full textIn this issue of Chem Catalysis, Zhao and co-workers describe an artificial metallohydrolase that is finally capable of matching the proficiency of enzymes. Using molecular imprinted polymeric nanoparticles, the authors have realized a catalytic system capable of cleaving activated and unactivated esters with shape selectivity
Synthesis conjugation, and immunological evaluation of phosphonoester analogues of serogroup A Neisseria Meningitidis a capsular polysaccharide.
No full textWorking in a Team: Development of a Device for Water Hardness Sensing Based on an Arduino-Nanoparticle System
No full textThis work describes a two-year project carried out in an Italian technical high school. Through integrated work, the activity involved the efforts of different teachers and students, particularly those in the Chemical, Electronic, and IT departments. They merged their complementary skills to create an inexpensive device that quickly measures water hardness. The pedagogical aspect of this work aimed to support and reinforce development of the key competences for lifelong learning recommended by the European Commission, especially by strengthening the logical-mathematical, digital, and social skills of the students. The device made is based on an Arduino board connected to a red LED and an optical sensor. The device is able to read the intensity of light transmitted through the sample and to independently convert this output into the water hardness expressed in French degrees. The color change used as information transducer is due to the aggregation of negative gold nanoparticles induced by the bivalent cations in solution. Working in school laboratories under teacher supervision, students connected and troubleshot the hardware system, synthesized and characterized the gold nanoparticles, and developed the software. Finally, the system was assembled inside a box composed of a rigid container, a sample holder, and a touchscreen display. Instructions for replicating this instrument are reported in the paper, while further details and explanations for instructors and students are provided in the Supporting Information
Opsonins and Dysopsonins of Nanoparticles: Facts, Concepts, and Methodological Guidelines
Full text linkUnderstanding the effects mediated by a set of nanoparticle (NP)-bound host biomolecules, often indicated with the umbrella term of NP corona, is essential in nanomedicine, nanopharmacology, and nanotoxicology. Among the NP-adsorbed proteome, some factors mediate cell binding, endocytosis, and clearing by macrophages and other phagocytes (opsonins), while some others display few affinities for the cell surface (dysopsonins). The functional mapping of opsonins and dysopsonins is instrumental to design long-circulating and nanotoxicologically safe next-generation nanotheranostics. In this review, we critically analyze functional data identifying specific proteins with opsonin or dysopsonin properties. Special attention is dedicated to the following: (1) the simplicity or complexity of the NP proteome and its modulation, (2) the role of specific host proteins in mediating the stealth properties of uncoated or polymer-coated NPs, and (3) the ability of the innate immune system, and, in particular, of the complement proteins, to mediate NP clearance by phagocytes. Emerging species-specific peculiarities, differentiating humans from preclinical animal models (the murine especially), are highlighted throughout this overview. The operative definition of opsonin and dysopsonin and the measurement schemes to assess their in vitro efficacy is critically re-examined. This provides a shared and unbiased approach useful for NP opsonin and dysopsonin systematic identification
Sensing with fluorescent nanoparticles
No full textFluorescent chemosensors are chemical systems that can detect and signal the presence of selected
analytes through variations in their fluorescence emission. Their peculiar properties make them
arguably one of the most useful tools that chemistry has provided to biomedical research, enabling the
intracellular monitoring of many different species for medical and biological purposes. In its simplest
design, a fluorescent chemosensor is composed of a fluorescent dye and a receptor, with a built-in
transduction mechanism that converts recognition events into variations of the emission properties of
the fluorescent dye. As soon as fluorescent nanoparticles became available, several applications in the
field of sensing were explored. Nanoparticles have been used not only as better-performing substitutes
of traditional dyes but also as multivalent scaffolds for the realization of supramolecular assemblies,
while their high surface to volume ratio allows for distinct spatial domains (bulk, external surface, pores
and shells) to be functionalized to a comparable extent with different organic species. Over the last few
years, nanoparticles proved to be versatile synthetic platforms for the implementation of new sensing
schemes
Nanoparticle-assisted NMR spectroscopy: A chemosensing perspective
No full textSensing methodologies for the detection of target compounds in mixtures are important in many different contexts, ranging from medical diagnosis to environmental analysis and quality assessment. Ideally, such detection methods should allow for both identification and quantification of the targets, minimizing the possibility of false positives. With very few exceptions, most of the available sensing techniques rely on the selective interaction of the analyte with some detector, which in turn produces a signal as a result of the interaction. This approach hence provides indirect information on the targets, whose identity is generally ensured by comparison with known standards, if available, or by the selectivity of the sensor system itself. Pursuing a different approach, NMR chemosensing aims at generating signals directly from the analytes, in the form of a (complete) NMR spectrum. In this way, not only are the targets unequivocally identified, but it also becomes possible to identify and assign the structures of unknown species. In this review we show how relaxation- and diffusion-based NMR techniques, assisted by appropriate nanoparticles, can be used to edit the 1H NMR spectrum of a mixture and extract the signals of specific target compounds. Monolayer-protected nanoparticles, in particular those made from gold, are well suited to this task because they provide a versatile, protein-size support to build or incorporate supramolecular receptors. Remarkably, the self-organized and multifunctional nature of the nanoparticle coating allows exploitation of different kinds of non-covalent interactions, to provide tailored binding sites for virtually any class of molecules. From the NMR standpoint, the reduced translational and rotational diffusion rates of bulky nanoparticles offer a way to manipulate the states of the monolayer spins and build a reservoir of magnetization that can be selectively transferred to the interacting analytes. In addition, the low correlation time and the enhanced rigidity of the coating molecules (due to their grafting and crowding on the particle surface) promote efficient spin diffusion, useful in saturation transfer experiments. The optimized combination of NMR experiments and nanoreceptors can ultimately allow the detection of relevant analytes in the micromolar concentration range, paving the way to applications in the diagnostic field and beyond
Hybrid nanoreceptors for high sensitivity detection of small molecules by NMR chemosensing
No full text“Nanoparticle-assisted NMR chemosensing” combines magnetization transfer NMR techniques with the recognition abilities of gold nanoparticles (AuNPs) to isolate the NMR spectrum of relevant organic species in mixtures. The efficiency of the magnetization transfer is crucial to set the detection limit of the technique. To this aim, a second generation of nanoreceptors obtained by the self-organization of 2 nm AuNPs onto the surface of bigger silica nanoparticles shows better magnetization transfer performances, allowing the detection of analytes in water down to 10 μM concentration using standard instrumentation
Factors Influencing the Activity of Nanozymes in the Cleavage of an RNA Model Substrate
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