The rapid recognition of intravenously injected colloidal carriers, such as liposomes and polymeric nanospheres from the blood by Kupffer cells, has initiated a surge of development for "Kupffer cell-evading" or long-circulating particles. Such carriers have applications in vascular drug delivery and release, site-specific targeting (passive as well as active targeting), as well as transfusion medicine. In this article we have critically reviewed and assessed the rational approaches in the design as well as the biological performance of such constructs. For engineering and design of long-circulating carriers, we have taken a lead from nature. Here, we have explored the surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition. Our analysis is then centered where such strategies have been translated and fabricated to design a wide range of particulate carriers (e.g., nanospheres, liposomes, micelles, oil-in-water emulsions) with prolonged circulation and/or target specificity. With regard to the targeting issues, attention is particularly focused on the importance of physiological barriers and disease states.

Long-Circulating and Target-Specific Nanoparticles: Theory to Practice

Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.

https://science.sciencemag.org/content/sci/263/5153/1600.full.pdf

Biodegradable long-circulating polymeric nanospheres

The Stability of Cyclodextrin Complexes in Solution.

https://nathan.instras.com/documentDB/paper-311.pdf

Poly(ethylene oxide)-poly(propylene oxide )-poly (ethylene oxide) block copolymer surfactants in aqueous solutions and at interfaces: thermodynamics, structure, dynamics, and modeling

Triplet photosensitizers (PSs) are compounds that can be efficiently excited to the triplet excited state which subsequently act as catalysts in photochemical reactions. The name is originally derived from compounds that were used to transfer the triplet energy to other compounds that have only a small intrinsic triplet state yield. Triplet PSs are not only used for triplet energy transfer, but also for photocatalytic organic reactions, photodynamic therapy (PDT), photoinduced hydrogen production from water and triplet-triplet annihilation (TTA) upconversion. A good PS should exhibit strong absorption of the excitation light, a high yield of intersystem crossing (ISC) for efficient production of the triplet state, and a long triplet lifetime to allow for the reaction with a reactant molecule. Most transition metal complexes show efficient ISC, but small molar absorption coefficients in the visible spectral region and short-lived triplet excited states, which make them unsuitable as triplet PSs. One obstacle to the development of new triplet PSs is the difficulty in predicting the ISC of chromophores, especially of organic compounds without any heavy atoms. This review article summarizes some molecular design rationales for triplet PSs, based on the molecular structural factors that facilitate ISC. The design of transition metal complexes with large molar absorption coefficients in the visible spectral region and long-lived triplet excited states is presented. A new method of using a spin converter to construct heavy atom-free organic triplet PSs is discussed, with which ISC becomes predictable, C60 being an example. To enhance the performance of triplet PSs, energy funneling based triplet PSs are proposed, which show broadband absorption in the visible region. Applications of triplet PSs in photocatalytic organic reactions, hydrogen production, triplet-triplet annihilation upconversion and luminescent oxygen sensing are briefly introduced.

Triplet photosensitizers: from molecular design to applications

Ketocoumarins: A new class of triplet sensitizers

The effect of surface modification of polystyrene latex particles on subsequent protein adsorption was investigated by photon correlation spectroscopy, sedimentation, and fluorescence anisotropy decay techniques. The surface modifiers used are a series of Pluronic triblock copolymer surfactants (PEO)a(PPO)b(PEO)a (where PEO is polyethylene oxide and PPO is polypropylene oxide). The hydrodynamic thickness of the adsorbed Pluronic copolymers is proportional to the PEO chain length a as well as the molecular weight of the surfactant, with Pluronic F108 and Tetronic 908 having the thickest layers. Undetectable protein adsorption was observed on such surfactant-coated particles. This was demonstrated by monitoring the unchanged particle size upon addition of human albumin, fibrinogen, or whole plasma, in contrast with size increase for the uncoated particles. This result was also confirmed by direct adsorption isotherm measurement using sedimentation method. Furthermore, the unchanged rotational correlation time of the protein molecules upon addition of Pluronic F108-coated polystyrene particles is also consistent with the above finding of protein resistance of the coated particles. Rotational correlation time was determined from the fluorescence anisotropy decay of an extrinsic probe, 1-pyrenesulfonyl chloride, covalently attached to the protein molecules.

Protein adsorption on pluronic copolymer-coated polystyrene particles

Protein Adsorption and Conformational Change on Small Polymer Particles

Oxazine 1 perchlorate (A) and oxazine 170 perchlorate (D) were selected to investigate the influence of cyclodextrins (CDs) on the dyes' aqueous solution aggregation equilibria. Through equilibrium processes, these days form inclusion complexes with β- and γ-CD. The amphiphile hexane sulfonate can be coincluded with D in γ-CD. We report determination of the stoichiometries of all inclusion complexes and measurement of all equilibrium constants; temperature effect data on some of the latter are also included

P. A. Martic

Papers

Ketocoumarins: A new class of triplet sensitizers

Protein adsorption on pluronic copolymer-coated polystyrene particles

Protein Adsorption and Conformational Change on Small Polymer Particles

Inclusion by cyclodextrins to control dye aggregation equilibria in aqueous solution

Cyclodextrin inclusion complexes of 1-pyrenebutyrate. The role of coinclusion of amphiphiles