Characterization of the soluble proteins from rabbit eye lens.
Abstract Fractionation of the soluble proteins of rabbit lens by gel chromatography on Sepharose 6B revealed six components, viz. HM-, α-, β 1 -, β 2 -, β 3 - and γ-crystallin. On isoelectric focusing α-crystallins revealed a diffuse region, whilst approximately 10 bands were found for the β-crystallins and 7–8 components for γ-crystallin. Immunoelectrophoretically HM-crystallin revealed two precipitin lines, one in the α- and one in the β-mobility range. Sedimentation coefficients of 18·0, 8·0, 3·7, 2·2 and 2·1 S were calculated for α-, β 1 -, β 2 -, β 3 - and γ-crystallin, respectively. By isoelectric focusing in the presence of 6 m -urea, 13 bands between pH 5·3 and 6·9 were found for HM-crystallin, approximately six bands between pH 5·6 and 6·9 for α-crystallin, about 13 bands between pH 5·9 and 7·0 for the β-crystallins and 7–8 major bands between pH 7·0 and 7·8 for γ-crystallin. Molecular weight estimation by SDS gel electrophoresis revealed values between 16 000 and 39 000 for HM-crystallin and the β-crystallins, whereas values of approximately 21 000 and 20 500 were found for α- and γ-crystallin.
Comparative and age-dependent aspects of crystallin size and distribution in human, rabbit, bovine, rat, chicken, duck, frog and dogfish lenses.
Lens extracts obtained from eight vertebrate species were analyzed using high-performance gel permeation chromatography with differential refractive index and low-angle laser light scattering detection. The elution patterns enabled the direct determination of the proportions of the crystallin classes as well as the molecular weights of the numerous size fractions in a more rapid and accurate way than previously. Concerning the mammalian species, also age-dependent aspects could be assessed by comparing the data obtained from the extracts of differently aged lenses and/or lens parts.
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.