Effect of chemical modification of thin C₆₀ fullerene films on the fundamental absorption edge

Fullerene C₆₀ films were grown using physical vapor deposition on Si substrates at room temperature. Then chemical modification with cross-linking these films was performed using the reaction with 1,8-octanediamine (DA) or octane-1,8- dithiol (DT). These chemically cross-linked C₆₀ films are capable of stable binding the Ag or Au nanoclusters. Optical properties of the obtained nanostructured hybrid films were investigated by both reflectance spectroscopy and spectral ellipsometry within the spectral range 1.55 to 5.0 eV at various angles of incidence. From the spectral dependences of the extinction coefficient in the region of optical absorption edge, the physical nature of the fundamental allowed direct band-gap transitions between HOMOLUMO states Eg, the optical absorption edge near the intrinsic transition Eo, and exponential tail of the density-of-states caused by defects have been determined. Influence of chemical modification and decoration of metal nanoparticles on the above mentioned parameters has been analyzed

Outcomes of accelerated corneal collagen cross-linking in keratoconus

Keratoconus (KC) is a degenerative noninflammatory disease of the cornea which is characterized be structural changes in the cornea which leads to progressive thinning and bulging in the central and/or peripheral part of the cornea and is accompanied by irregular astigmatism and significant vision impairment. Today, keratoconus treatment is focused on a stage of disease development. At progressive KC stages (II-III), corneal collagen cross-linking is performed. At the present, a latest-generation unit (UV-X™2000, Avedro) is used to perform accelerated cross-linking, which allows for a threefold decrease of the procedure duration (to 10 minutes) compared to the standard protocol Material and Methods. Corneal collagen cross-linking was performed in 71 patients (100 eyes). Results. Accelerated corneal collagen cross-linking for keratoconus stages II-III made it possible to stabilize the pathological process in 100% of cases, based on 12 month follow-up. Keratoconus stabilization was accompanied by: a decrease of astigmatism by 1.4 D and of the corneal refractive power by 3.2D; an increase of the corneal thickness by 8.8 nm; an increase of UCVA and BCVA in 96.5% and 89.6% of cases, respectively; and recovery of normal corneal architectonics according to confocal biomicroscopy data. Subjectively, 64 patients (90%) noted the improvement in the vision quality and better tolerance to spectacles correction

Structure of the chorioretinal complex in the rabbit eye after vitrectomy. Report 1. Vitreous cavity irrigation with different temperature solutions for 30 minutes

Background: It remains poorly understood what should be the temperature of the irrigating solution for intraocular surgery and how long it is reasonable to use irrigating solutions during vitrectomy. Purpose: To investigate the structure of the rabbit chorioretinal complex after vitrectomy with the use of irrigating solutions having different temperatures for 30 minutes. Materials and Methods: Twelve Chinchilla rabbits (24 eyes) were divided into two experimental groups and one control group. The two experimental groups, each of 5 rabbits (10 eyes), underwent a three-port pars plana vitrectomy with either 22°C or 5°C irrigating solution. Two intact rabbits (4 eyes) were used as controls for comparison. The duration of irrigation/aspiration was 30 minutes. The material for histology was obtained at days 1 and 7 after surgery, and the chorioretinal complex was histologically examined by light microscopy. Results: Groups of animals subjected to thirty-minute vitreous cavity cooling with the 22 °C or 5°С irrigating solution showed no structural changes in the retinal and choroidal components compared to intact animals. Conclusion: The 22 °C or 5°С irrigating solution produces no structural changes in the retina and choroid, and can be used in the vitreoretinal surgical procedure for continuous vitreous cavity irrigation lasting for up to 30 minutes

Fluorescent gold nanoclusters stabilized on halloysite nanotubes: in vitro study on cytotoxicity

Fluorescent gold nanoclusters (AuNCs) with an average diameter of 2.7 ± 1.0 nm stabilized with 11-mercaptoundecanoic acid were supported on halloysite nanotubes modified with aminosilane. The cytotoxicity of the obtained fluorescent material was investigated in A549 human cells. The AuNCs stabilized on halloysite showed good uptake by the cells. The material did not cause a pronounced toxic effect and visible membrane damage within the 25–50 μg/mL concentration range. An increase in nanocomposite concentration to 100 μg/mL led to massive cell death via apoptosis. This concentration-dependent toxicity mechanism allows for using AuNCs stabilized on halloysite for halloysite visualization in biological objects, bioimaging, and cancer therapy

Structure of the chorioretinal complex in the rabbit eye after vitrectomy. Report 2. Vitreous cavity irrigation with different temperature solutions for 60 minutes

Background: It remains poorly understood what should be the temperature of the irrigation solution for intraocular surgery and how long it is reasonable to use irrigation solutions during vitrectomy. Purpose: To investigate the structure of rabbit chorioretinal complex after vitrectomy with the use of irrigation solutions having different temperatures for 60 minutes. Materials and Methods: Twelve Chinchilla rabbits (24 eyes) were divided into two experimental groups and one control group. The two experimental groups, each of 5 rabbits (10 eyes), underwent a three-port pars plana vitrectomy with either 22°C or 5°C irrigation solution. Two intact rabbits (4 eyes) were used as controls for comparison. The duration of irrigation/aspiration was 60 minutes. Specimens for histology were obtained at days 1 and 7 after surgery. The chorioretinal complex (i.e., the choroid and retina) was histologically examined. Results: After vitrectomy with 60-minute continuous vitreous cavity cooling with either the 22°C or 5°C irrigation solution, we found retinal structural changes in the form of uneven edema, (a) predominantly in the inner retinal layers, at day 1, and (b) in both the inner and outer retinal layers, at day 7. There were destructive changes in the inner retinal layers on some slides from rabbits of both groups. In addition, the choroid appeared somewhat thickened. Conclusion: In the rabbit eyes after vitrectomy with 60-minute continuous vitreous cavity cooling with either the 22°C or 5°C irrigation solution, we found the uneven retinal edema that is likely to be mediated by aseptic inflammatory response to cooling-induced and mechanical damage to the retina, and might be also associated with the composition of the irrigation fluid