Investigating lyophilization of lipid nanocapsules with fluorescence correlation spectroscopy

Modeling and Control of Single-Cell Migration Induced by a Chemoattractant-Loaded Microbead

Cell migration plays an essential role in cancer cell study. Investigation of a novel method for controlling cell migration movement can help develop new therapeutic strategies. In this paper, a chemoattractant-loaded microbead, which is controlled by optical tweezers, is used to stimulate a target cell to accomplish automated migration along a desired path while avoiding obstacles. Models of both tweezers-bead and bead-cell interactions are investigated. A dual closed-loop control strategy is proposed, which includes an inner tweezers-bead control loop and an outer bead-cell control loop. A proportional-integral feedback plus feedforward controller is used to control the inner loop, and an active disturbance rejection controller is used for the outer loop, which can address the cell migration modeling errors and unknown external disturbances. A traffic rule based on interference-clearing mechanism is also proposed to reduce external disturbances on the system by preventing other particles from interfering with the migration process. The effectiveness of the proposed control approach is verified by simulations and experiments on migrating leukemia cancer cells.

Nanocapsules: the weapons for novel drug delivery systems

INTRODUCTION

Nanocapsules, existing in miniscule size, range from 10 nm to 1000 nm. They consist of a liquid/solid core in which the drug is placed into a cavity, which is surrounded by a distinctive polymer membrane made up of natural or synthetic polymers. They have attracted great interest, because of the protective coating, which are usually pyrophoric and easily oxidized and delay the release of active ingredients.

METHODS

Various technical approaches are utilized for obtaining the nanocapsules; however, the methods of interfacial polymerization for monomer and the nano-deposition for preformed polymer are chiefly preferred. Most important characteristics in their preparation is particle size and size distribution which can be evaluated by using various techniques like X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolu¬tion transmission electron microscopy, X-ray photoelectron spectroscopy, superconducting quantum interference device, multi angle laser light scattering and other spectroscopic techniques.

RESULTS

Nanocapsules possessing extremely high reproducibility have a broad range of life science applications. They may be applied in agrochemicals, genetic engineering, cosmetics, cleansing products, wastewater treatments, adhesive component applications, strategic delivery of the drug in tumors, nanocapsule bandages to fight infec¬tion, in radiotherapy and as liposomal nanocapsules in food science and agriculture. In addition, they can act as self-healing materials.

CONCLUSION

The enhanced delivery of bio¬active molecules through the targeted delivery by means of a nanocapsule opens numerous challenges and opportunities for the research and future development of novel improved therapies.

Fluorescence correlation spectroscopy in biology, chemistry, and medicine

This review describes the method of fluorescence correlation spectroscopy (FCS) and its applications. FCS is used for investigating processes associated with changes in the mobility of molecules and complexes and allows researchers to study aggregation of particles, binding of fluorescent molecules with supramolecular complexes, lipid vesicles, etc. The size of objects under study varies from a few angstroms for dye molecules to hundreds of nanometers for nanoparticles. The described applications of FCS comprise various fields from simple chemical systems of solution/micelle to sophisticated regulations on the level of living cells. Both the methodical bases and the theoretical principles of FCS are simple and available. The present review is concentrated preferentially on FCS applications for studies on artificial and natural membranes. At present, in contrast to the related approach of dynamic light scattering, FCS is poorly known in Russia, although it is widely employed in laboratories of other countries. The goal of this review is to promote the development of FCS in Russia so that this technique could occupy the position it deserves in modern Russian science.

Intracellular delivery of bioactive molecules using light-addressable nanocapsules

This paper describes a method by which molecules that are impermeable to cells are encapsulated in dye-sensitized lipid nanocapsules for delivery into cells via endocytosis. Once inside the cells, the molecules are released from the lipid nanocapsules into the cytoplasm with a single nanosecond pulse from a laser in the far red (645 nm). We demonstrate this method with the intracellular release of the second messenger IP(3) in CHO-M1 cells and report that calcium responses from the cells changed from a sustained increase to a transient spike when the average number of IP(3) released is decreased below 50 molecules per nanocapsule. We also demonstrate the delivery of a 23 kDa O(6)-alkylguanine-DNA alkyltransferase (AGT) fusion protein into Ba/F3 cells to inhibit a key player BCR-ABL in the apoptotic pathway. We show that an average of ∼8 molecules of the inhibitor is sufficient to induce apoptosis in the majority of Ba/F3 cells.

Optical Trapping Enabled Parallel Delivery of Biological Stimuli with High Spatial and Temporal Resolution

We have developed a method that employs nanocapsules, optical trapping, and single-pulse laser photolysis for delivering bioactive molecules to cells with both high spatial and temporal resolutions. This method is particularly suitable for a cell-culture setting, in which a single nanocapsule can be optically trapped and positioned at a pre-defined location next to the cell, followed by single-pulse laser photolysis to release the contents of the nanocapsule onto the cell. To parallelize this method such that a large array of nanocapsules can be manipulated, positioned, and photolyzed simultaneously, we have turned to the use of spatial light modulators and holographic beam shaping techniques. This paper outlines the progress we have made so far and details the issues we had to address in order to achieve efficient parallel optical manipulations of nanocapsules and particles.