Functionalization of manganite nanoparticles and their interaction with biologically relevant small ligands: picosecond time-resolved FRET studies

We report molecular functionalization of the promising manganite nanoparticles La0.67Sr0.33MnO3 (LSMO) for their solubilization in aqueous environments. The functionalization of individual NPs with the biocompatible citrate ligand, as confirmed by Fourier transform infrared (FTIR) spectroscopy, reveals that citrates are covalently attached to the surface of the NPs. UV-VIS spectroscopic studies on the citrate functionalized NPs reveals an optical band in the visible region. Uniform size selectivity (2.6 nm) of the functionalization process is confirmed from high resolution transmission electron microscope (HRTEM). In the present study we have used the optical band of the functionalized NPs to monitor their interaction with other biologically important ligands. Forster resonance energy transfer (FRET) of a covalently attached probe 4-nitrophenylanthranilate (NPA) with the capped NPs confirm the attachment of the NPA ligands to the surface functional group (-OH) of the citrate ligand. The FRET of a DNA base mimic, 2-aminopurine (2AP), with the NPs confirms the surface adsorption of 2AP. Our study may find relevance in the study of the interaction of individual manganite NPs with drug/ligand molecules

Input-Output Linearization with Delay Cancellation for Nonlinear Delay Systems: the Problem of the Internal Stability,

SUMMARY This paper investigates the issue of the internal stability of nonlinear delay systems controlled with a feedback law that performs exact input-output, linearization and delay cancellation. In previous works the authors showed that, unlike with the case of systems without state delays, when the relative degree is equal to the number of state variables and the output is forced to be identically zero, delay systems still possess a non-trivial internal state dynamics. Not only, in the same conditions delay systems are also characterized by a non-trivial input dynamics. Obviously, both internal state and input dynamics should give bounded trajectories, otherwise the exact input-output linearization and delay cancellation technique cannot be applied. This paper studies the relationships between the internal state and input dynamics of a controlled nonlinear delay system. An interesting result is that a suitable stability assumption on the internal state dynamics ensures that, when the output is asymptotically driven to zero, both the state and control variables asymptotically decay to zero

Input-Output Linearization with Delay Cancellation for Nonlinear Delay Systems: the Problem of the Internal Stability,

SUMMARY This paper investigates the issue of the internal stability of nonlinear delay systems controlled with a feedback law that performs exact input-output, linearization and delay cancellation. In previous works the authors showed that, unlike with the case of systems without state delays, when the relative degree is equal to the number of state variables and the output is forced to be identically zero, delay systems still possess a non-trivial internal state dynamics. Not only, in the same conditions delay systems are also characterized by a non-trivial input dynamics. Obviously, both internal state and input dynamics should give bounded trajectories, otherwise the exact input-output linearization and delay cancellation technique cannot be applied. This paper studies the relationships between the internal state and input dynamics of a controlled nonlinear delay system. An interesting result is that a suitable stability assumption on the internal state dynamics ensures that, when the output is asymptotically driven to zero, both the state and control variables asymptotically decay to zero