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The use of carbon nanotubes as anticancer drug delivery cargo systems is a promising modality as they are able to perforate cellular membranes and transport the carried therapeutic molecules into the cellular components. Our work describes the encapsulation process of a common anticancer drug, Isatin (1H-indole-2,3-dione) as a guest molecule, in a capped single-walled carbon nanotube (SWCNT) host with chirality of (10,10). The encapsulation process was modelled, considering an aqueous solution, by a molecular dynamics (MD) simulation under a canonical NVT ensemble. The interactions between the atoms of Isatin were obtained from the DREIDING force filed. The storage capacity of the capped SWCNT host was evaluated to quantify its capacity to host multiple Isatin molecules. Our results show that the Isatin can be readily trapped inside the volume cavity of the capped SWCNT and it remained stable, as featured by a reduction in the van der Waals forces between Isatin guest and the SWCNT host (at approximately − 30 kcal mol−1) at the end of the MD simulation (15 ns). Moreover, the free energy of encapsulation was found to be − 34 kcal mol−1 suggesting that the Isatin insertion procedure into the SWCNT occurred spontaneously. As calculated, a capped SWCNT (10,10) with a length of 30 Å, was able to host eleven (11) molecules of Isatin, that all remained steadily encapsulated inside the SWCNT volume cavity, showing a potential for the use of carbon nanotubes as drug delivery cargo systems.

BACKGROUND: Glaucoma, a characteristic type of optic nerve degeneration in the posterior pole of the eye, is a common cause of irreversible vision loss and the second leading cause of blindness worldwide. As an optic neuropathy, glaucoma is identified by increasing degeneration of retinal ganglion cells (RGCs), with consequential vision loss. Current treatments only postpone the development of retinal degeneration, and there are as yet no treatments available for this disability. Recent studies have shown that replacing lost or damaged RGCs with healthy RGCs or RGC precursors, supported by appropriately designed bio-material scaffolds, could facilitate the development and enhancement of connections to ganglion cells and optic nerve axons. The consequence may be an improved retinal regeneration. This technique could also offer the possibility for retinal regeneration in treating other forms of optic nerve ailments through RGC replacement. METHODS: In this brief review, we describe the innovations and recent developments in retinal regenerative medicine such as retinal organoids and gene therapy which are specific to glaucoma treatment and focus on the selection of appropriate bio-engineering principles, biomaterials and cell therapies that are presently employed in this growing research area. RESULTS: Identification of optimal sources of cells, improving cell survival, functional integration upon transplantation, and developing techniques to deliver cells into the retinal space without provoking immune responses are the main challenges in retinal cell replacement therapies. CONCLUSION: The restoration of visual function in glaucoma patients by the RGC replacement therapies requires appropriate protocols and biotechnology methods. Tissue-engineered scaffolds, the generation of retinal organoids, and gene therapy may help to overcome some of the challenges in the generation of clinically safe RGCs.

The anisotropic mechanical properties of parts that are fabricated using acrylonitrile butadiene styrene (ABS) polymer relative to part-built orientation employing the fused deposition modelling process are reported in this work. ABSplus-P430 polymer was used to investigate the effects of infill orientation on the parts’ mechanical properties under tensile and compression loading. Results revealed that infill orientation strongly affected the tensile properties of fabricated ABS samples. Specifically, the values for Young’s modulus ranged from ~1.5 to ~2.1 GPa, ultimate tensile strength from ~12.0 to ~22.0 MPa, yield strength from ~1.0 to ~21.0 MPa, and elongation-at-break from ~0.2 to ~4.8% for different infill orientations. Samples with infill orientation aligned to the vertical (i.e. Z-) axis displayed the highest values relative to all other infill orientations investigated. Mechanical properties anisotropy was lower for parts under compressive loading, such that the Young’s modulus, ultimate compressive and yield strength were weakly correlated with infill orientation apart from samples whose built orientation was aligned at 45° to the vertical Z-axis. The latter samples displayed inferior mechanical properties under all compressive tests. The effects of sample gauge thickness on tensile properties and ABS sample micro- and bulk- hardness with respect to infill orientation are also discussed.

Recent advances in cell transplantation technologies have shown that polymeric fibrous tissue-engineered scaffolds provide a suitable physical environment, including the structural support, for cell delivery and effectively mimic the transplanted cells’ extracellular matrix. Our study investigates the structure, composition and properties of three most commonly used polyester-based biopolymer materials blended with poly(e-caprolactone) (PCL) at 2:1 (wt.%) ratio, namely, poly(glycerol sebacate) (PGS)/PCL, polylactic-co-glycolic acid (PLGA)/PCL, poly-l-lactide (PLLA)/PCL and pure PCL as carrier vehicles for retinal progenitor cell (RPC) attachment and RPC proliferation. The physicochemical properties of PGS/PCL, PLLA/PCL, PLGA/PCL and pure PCL fibrous scaffolds, fabricated under the identical electrospinning conditions, were analysed employing scanning electron microscopy, contact angle analysis, Raman spectroscopy, electrical and ionic conductivity measurements, and supplemented by an in-vitro RPC adhesion and proliferation studies. Our findings have shown that PGS/PCL scaffolds promote RPC attachment and RPC proliferation more favourably compared to other polymeric blends and pure PCL, owing to a combination of advantageous surface and bulk properties, overall demonstrating a potential for PGS/PCL blend to become a suitable vehicle for RPC delivery in a possible future clinical therapy for the treatment of retinal degenerative disorders.

One of the main functions of the skin is to reduce the amount of water evaporating from the surface of a human body with outermost layer of the epidermis, stratum corneum (SC), forming a barrier, which protects underlying tissue from dehydration. Empirical data obtained for water penetration in SC are normally analysed using mathematical models, among which the homogeneous membrane (HM) model is commonly employed to describe transport kinetics in SC. However, the HM model failed to fit simultaneously the experimental data for water permeation and desorption (Anissimov YG, Roberts MS. 2009. J Pharm Sci 98:772-781), as the model does not account for a complex structure of SC and irregular distribution of corneocytes. Our previous work (Anissimov YG, Roberts MS. 2009. J Pharm Sci 98:772-781) introduced a slow binding (SB) model that is more aligned with the true biological structure of SC. This report provides an alternative/additional model to both the HM and SB models and takes into account the distribution of effective pathways across SC for water transport.

We report the synthesis of extended two-dimensional organic networks on Cu(111), Ag(111), Cu(110), and Ag(110) from thiophene-based molecules. A combination of scanning tunnelling microscopy and X-ray photoemission spectroscopy yields insight into the reaction pathways from single molecules towards the formation of two-dimensional organometallic and polymeric structures via Ullmann reaction dehalogenation and C-C coupling. The thermal stability of the molecular networks is probed by annealing at elevated temperatures of up to 500 °C. On Cu(111) only organometallic structures are formed, while on Ag(111) both organometallic and covalent polymeric networks were found to coexist. The ratio between organometallic and covalent bonds could be controlled by means of the annealing temperature. The thiophene moieties start degrading at 200 °C on the copper surface, whereas on silver the degradation process becomes significant only at 400 °C. Our work reveals how the interplay of a specific surface type and temperature steers the formation of organometallic and polymeric networks and describes how these factors influence the structural integrity of two-dimensional organic networks.

Inclusions of sp-hybridised, trans-polyacetylene [trans-(CH)x] and poly(p-phenylene vinylene) (PPV) chains are revealed using resonant Raman scattering (RRS) investigation of amorphous hydrogenated carbon (a-C:H) films in the near IR - UV range. The RRS spectra of trans-(CH)x core Ag modes and the PPV CC-H phenylene mode are found to transform and disperse as the laser excitation energy \hbar{\omega}L is increased from near IR through visible to UV, whereas sp-bonded inclusions only become evident in UV. This is attributed to \hbar{\omega}L probing of trans-(CH)x chain inhomogeneity and the distribution of chains with varying conjugation length; for PPV to the resonant probing of phelynene ring disorder; and for sp segments, to \hbar{\omega}L probing of a local band gap of end-terminated polyynes. The IR spectra analysis confirmed the presence of sp, trans-(CH)x and PPV inclusions. The obtained RRS results for a-C:H denote differentiation between the core Ag trans-(CH)x modes and the PPV phenylene mode. Furthermore, it was found that at various laser excitation energies the changes in Raman spectra features for trans-(CH)x segments included in an amorphous carbon matrix are the same as in bulk trans-polyacetylene. The latter finding can be used to facilitate identification of trans-(CH)x in the spectra of complex carbonaceous materials., Comment: 31 page, 9 figures

Diamondlike amorphous carbon films have been deposited on silicon and quartz substrates by laser ablation of graphite using 120 fs pulses from an amplified Ti:sapphire laser operating at 800 nm. Ultraviolet/visible (UV/VIS) and micro-Raman spectra of these materials have shown that the sp3-bonded carbon fraction in these films is ≈27%, 55%, and 20% when deposition occurs at substrate temperatures of 77, 300, and 573 K, respectively. The presence of sp1 chains in these films is indicated by the appearance of an excitation band at 2000–2100 cm−1 in UV-Raman spectra. We also find a remarkable increase in the Tauc energy gap calculated from in situ UV/VIS optical spectra immediately after exposure to air together with a 1 eV redshift of the C 1s core-level energy in x-ray photoelectron spectra of these samples. The properties of sp1-, sp2- and sp3-bonded components of these materials have also been studied using UV/VIS Raman spectroscopy. The enhanced stability of sp1 chains in tetrahedral carbon matrix is di...

There is a notion that in carbonaceous materials the sp3 hybridised fraction determines the mechanical properties, while the sp2 fraction controls the electro-optical properties. We investigated a narrow range of a-C:H films synthesised in an open hydrocarbon plasma source. The a-C:H films displayed unambiguous variation in mechanical properties as measured by nanoindentation measurements. However the proportion of sp3 constituent, determined using X-ray C1s core-level photoelectron spectroscopy and Fourier transform infrared spectroscopy, was found to be essentially the same for all studied samples. The Tauc gap was found to be controlled by the perturbation of the π tail states of sp2 phase and its magnitude varied inversely with a surface conduction gap determined by scanning tunnelling microscopy measurements. These results indicate that mechanical properties of a-C:H films are also influenced by the degree of disorder of the sp2 fraction, as characterised by bond saturation and symmetry.

Surface modification of poly( l lactide) ( l -PLA) and polycaprolactone (PCL) bioresorbable polymers by radio-frequency thermal glow discharge plasma is reported. Improved biocompatibility of l -PLA and PCL materials was obtained by employing hydroxyapatite target sputtering in Ar + plasma as evidenced by the change of l -PLA and PCL properties from highly hydrophobic to hydrophilic, with absolute wettability obtained for both materials, and enhanced cell line EA-hy 926 attachment to modified surfaces. Surface roughness and surface free energy were found to increase significantly for both polymers under prolonged plasma exposure and, a longer chain aliphatic PCL were found to display a marginally better post plasma-treated biocompatibility compared to l -PLA.

A comparative study of carbon bonding states and Raman spectra is reported for amorphous diamondlike carbon films deposited using 120 fs and 30 ns pulsed laser ablation of graphite. The presence of sp(1) chains in femtosecond carbon films is confirmed by the appearance of a broad excitation band at 2000-2200 cm(-1) in UV-Raman spectra. Analysis of Raman spectra indicates that the concentrations of sp(1)-, sp(2)-, and sp(3)-bonded carbon are approximately 6%, approximately 43%, and approximately 51%, respectively, in carbon films prepared by femtosecond laser ablation. Using surface enhanced Raman spectroscopy, specific vibrational frequencies associated with polycumulene, polyyne, and trans-polyacetylene chains have been identified. The present study provides further insight into the composition and structure of tetrahedral carbon films containing both sp(2) clusters and sp(1) chains.

The synthesis of polymer-like amorphous carbon (a-C:H) thin-films by microwave excited collisional hydrocarbon plasma process is reported. Stable and highly aromatic a-C:H were obtained containing significant inclusions of poly(p-phenylene vinylene) (PPV). PPV confers universal optoelectronic properties to the synthesised material. That is a-C:H with tailor-made refractive index are capable of becoming absorption-free in visible (red) - near infrared wavelength range. Production of large aromatic hydrocarbon including phenyl clusters and/or particles is attributed to enhanced coagulation of elemental plasma species under collisional plasma conditions. Detailed structural and morphological changes that occur in a-C:H during the plasma synthesis are also described., Comment: 12 pages, 4 figures

The resonant Raman scattering in N-IR - UV range from amorphous hydrogenated carbon (a-C:H) reveal inclusions of trans-polyacetylene (trans-(CH)x) chains with approximate length of up to 120 C=C units and inclusions of poly(p-phenylene vinylene) (PPV) polymer chains. The PPV is evidenced by a strong dispersive mode at ca. 1175 cm-1. It was found that the Raman response from core Ag trans-(CH)x modes incorporated into a-C:H to changing excitation energy is identical to of free-standing chains thus facilitating identification of trans-(CH)x in complex carbonaceous materials spectra., 11 pages, 3 figures

Microscopic phase transformation from graphite to sp-bonded carbon chains (carbyne) and nanodiamond has been induced by femtosecond laser pulses on graphite surface. UV/surface enhanced Raman scattering spectra and x-ray photoelectron spectra displayed the local synthesis of carbyne in the melt zone while nanocrystalline diamond and trans-polyacetylene chains form in the edge area of gentle ablation. These results evidence possible direct "writing" of variable chemical bonded carbons by femtosecond laser pulses for carbon-based applications.