Particle size measurement by means of optical spectrometry of single particles depends substantially on the angular range of light scattering and the refractive index of the particle. Knowledge of the latter determines implicitly the accuracy of measurement. In contrast to commonly used instrumental systems the configuration of the design concept presented here consists of two laser illumination sources with different wavelengths and four angular ranges for the collection of scattered light. As a result a set of four independent pulses from each measured particle can be obtained allowing simultaneous assessment of particle size and its complex refractive index. Based on the Mie theory of light scattering, light collection angles yielding a single-valued aerosol size measurement were identified and used to design a new optical system. Based on the modelling of the performance for an assumed instrumental arrangement the sizing errors were found to be about 2%. The accuracy of assessment of the complex index of refraction was found to be of the order of 10% over the range of particle diameters investigated (0.1-10 µm). The theoretical results show clearly the capability of this novel instrumental design for the measurement of aerosol particle sizes, their density and optical properties. Based on these model calculations an experimental set-up is under construction.

Marketed dosage forms fail to deliver anti-tubercular drugs directly to the lungs in pulmonary Tuberculosis (TB). Therefore, nanomediated isoniazid (INH)-loaded dry powder for inhalation (Nano-DPI) was developed for macrophage-targeted delivery in TB. Mannosylated chitosan (MC) and hyaluronic acid (HA) with an affinity for the surface mannose and CD44 receptors of macrophages were used in conjugation to prepare hybrid nanosuspension by ionic gelation method using cross-linker, sodium tri-polyphosphate (TPP) followed by freeze-drying to obtain a dry powder composed of nanoparticles (INH-MC/HA NPs). Nanoformulations were evaluated for aerodynamic characteristics, cytotoxicity, hemocompatibility, macrophage phenotype analysis, and immune regulation. Cellular uptake imaging was also conducted to evaluate the uptake of NPs. The nanopowders did not pose any significant toxicity to the cells, along with good compatibility with red blood cells (RBCs). The pro-inflammatory costimulatory markers were upregulated, demonstrating the activation of T-cell response. Moreover, the NPs did not show any tolerogenic effect on the macrophages. Furthermore, confocal imaging exhibited the translocation of NPs in the cells. Altogether, the findings present that nano-DPI was found to be a promising vehicle for targeting macrophages.

Fluorescence correlation spectroscopy (FCS) and related distribution analysis techniques have become extremely important and widely used research tools for analyzing the dynamics, kinetics, interactions, and mobility of biomolecules. However, it is not widely recognized that photophysical dynamics can dramatically influence the calibration of fluctuation spectroscopy instrumentation. While the basic theories for fluctuation spectroscopy methods are well established, there have not been quantitative models to characterize the photophysical-induced variations observed in measured fluctuation spectroscopy data under varied excitation conditions. We introduce quantitative models to characterize how the fluorescence observation volumes in one-photon confocal microscopy are modified by excitation saturation as well as corresponding models for the effect of the volume changes in FCS. We introduce a simple curve fitting procedure to model the role of saturation in FCS measurements and demonstrate its accuracy in fitting measured correlation curves over a wide range of excitation conditions.