In this work, drug release from matrices with an inert nucleus using Monte Carlo simulation was studied. Drug-excipient systems were simulated, where the drug is a soluble material while the excipient is a non-soluble material. In the center of these devices, an inert nucleus was placed. The release of the drug was unidirectional and the results were fitted to the square root of time law (Higuchi law), the power law and the Weibull equation. The percolation threshold of the drug was found to be near 0.35 close to the expected value for the cubic lattice, the difference is due to the finite and rather small size of the systems in study as well as to the fact that the lattice in use is not exactly cubic. Near the percolation threshold, the parameters of the different release models presented a drastic change; this was due to a phase transition of the system. On the other hand, it was found that the size of the matrix system modifies the transport properties of the release platform. In general, the release kinetics was adequately described by the Weibull equation.
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http://dx.doi.org/10.1016/j.ijpharm.2008.10.023 | DOI Listing |
Nucleic Acids Res
October 2024
Department of Biology, Brandeis University, Waltham, MA 02451, USA.
Visualizing and measuring molecular-scale interactions in living cells represents a major challenge, but recent advances in single-molecule super-resolution microscopy are bringing us closer to achieving this goal. Single-molecule super-resolution microscopy enables high-resolution and sensitive imaging of the positions and movement of molecules in living cells. HP1 proteins are important regulators of gene expression because they selectively bind and recognize H3K9 methylated (H3K9me) histones to form heterochromatin-associated protein complexes that silence gene expression, but several important mechanistic details of this process remain unexplored.
View Article and Find Full Text PDFCell Mol Bioeng
June 2024
Division of Bioengineering, Osaka University, Toyonaka, 560-0043 Japan.
Introduction: The diffusion of cell components such as proteins is crucial to the function of all living cells. The abundance of macromolecules in cells is likely to cause a state of macromolecular crowding, but its effects on the extent of diffusion remain poorly understood.
Methods: Here we investigate the diffusion rate in three distinct locations in mesenchymal cell types, namely the open cytoplasm, the stress fibers in the open cytoplasm, and those below the nucleus using three kinds of biologically inert green fluorescent proteins (GFPs), namely a monomer, dimer, and trimer GFP.
Nat Phys
May 2024
Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK.
The nuclear pore complex regulates nucleocytoplasmic transport by means of a tightly synchronized suite of biochemical reactions. The physicochemical properties of the translocating cargos are emerging as master regulators of their shuttling dynamics. As well as being affected by molecular weight and surface-exposed amino acids, the kinetics of the nuclear translocation of protein cargos also depend on their nanomechanical properties, yet the mechanisms underpinning the mechanoselectivity of the nuclear pore complex are unclear.
View Article and Find Full Text PDFEur J Cell Biol
September 2024
Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, Girona ES-17003, Spain; Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, Girona ES-17003, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Barcelona ES-08010, Spain. Electronic address:
Sperm chromatin is distinct from somatic cell chromatin, as a result of extensive remodeling during the final stages of spermatogenesis. In this process, the majority of histones is replaced with protamines. The chromatin is consequently highly condensed and inert, which facilitates protection of the DNA.
View Article and Find Full Text PDFAnal Chem
June 2024
State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
Visualization of the mitochondrial state is crucial for tracking cell life processes and diagnosing disease, while fluorescent probes that can accurately assess mitochondrial status are currently scarce. Herein, a fluorescent probe named "" was designed and prepared, which can target mitochondria via the mitochondrial membrane potential. Upon pathology or external stimulation, can be released from the mitochondria and accumulate in the nucleolus to monitor the status of mitochondria.
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