Dielectric relaxations in amorphous polymers with complex chain architectures
By combining thermostimulated current and dynamic dielectric spectroscopies, the dielectric properties characteristic of the molecular mobility can be described over a very broad frequency range. The study of dielectric relaxations of phosphorus-containing dendrimers in the sub-glass transition region, and of poly(n-alkyl methacrylates) at and above the glass transition region allows us to gain insight into the molecular dynamics of complex architecture systems. From these sets of data we make an attempt to propose a structural interpretation of molecular mobility through the glass transition.
Cell Biology of Extracellular Matrix
Introductory Remarks.- I. What Is Extracellular Matrix?.- 1 Collagen.- 2 Proteoglycans: Structure and Function.- 3 The Elastic Fiber.- 4 Fibronectin and Other Cell Interactive Glycoproteins.- II. How Do Cells Produce the Matrix?.- 5 Proteoglycans: Metabolism and Pathology.- 6 Collagen Biosynthesis.- 7 Matrix Assembly.- 8 Extracellular Matrix Degradation.- III. What Does Matrix Do for Cells?.- 9 Proteoglycans and Hyaluronan in Morphogenesis and Differentiation.- 10 Integrins as Receptors for Extracellular Matrix.- 11 The Glomerular Basement Membrane: A Selective Macromolecular Filter.- 12 Collagen and Other Matrix Glycoproteins in Embryogenesis.
Recent progress in engineering near-infrared persistent luminescence nanoprobes for time-resolved biosensing/bioimaging
Persistent luminescence nanoprobes (PLNPs) can remain luminescent after ceasing excitation. Due to the ultra-long decay time of persistent luminescence (PersL), autofluorescence interference can be efficiently eliminated by collecting PersL signal after autofluorescence decays completely, thus the imaging contrast and sensing sensitivity can be significantly improved. Since near-infrared (NIR) light shows reduced scattering and absorption coefficient in penetrating biological organs or tissues, near-infrared persistent luminescence nanoprobes (NIR PLNPs) possess deep tissue penetration and offer a bright prospect in the areas of in vivo biosensing/bioimaging. In this review, we firstly summarize the design of different types of NIR PLNPs for biosensing/bioimaging, such as transition metal ions-doped NIR PLNPs, lanthanide ions-doped NIR PLNPs, organic molecules-based NIR PLNPs, and semiconducting polymer self-assembled NIR PLNPs. Notably, organic molecules-based NIR PLNPs and semiconductor self-assembled NIR PLNPs, for the first time, were introduced to the review of PLNPs. Secondly, the effects of different types of charge carriers on NIR PersL and luminescence decay of NIR PLNPs are significantly emphasized so as to build up an in-depth understanding of their luminescence mechanism. It includes the regulation of valence band and conduction band of different host materials, alteration of defect types, depth and concentration changes caused by ion doping, effective radiation transitions and energy transfer generated by different luminescence centers. Given the design and potential of NIR PLNPs as long-lived luminescent materials, the current challenges and future perspective in this rapidly growing field are also discussed.