Kinked-stepped, high Miller index surfaces of metal crystals are chiral and, therefore, exhibit enantiospecific properties. Previous temperature-programmed desorption (TPD) spectra have shown that the desorption energies of R-3-methylcyclohexanone (R-3-MCHO) on the chiral Cu(643)(R) and Cu(643)(S) surfaces are enantiospecific (J. Am. Chem. Soc. 2002, 124, 2384). Here, a comparison of the TPD spectra from Cu(111), Cu(221), Cu(533), Cu(653)(R&S), and Cu(643)(R&S) surfaces reveals that the enantiospecific desorption occurs from the chiral kink sites on the Cu(643) surfaces. Titration of the chiral kink sites with I atoms confirms this assignment of desorption features in the TPD spectra. Finally, the enantiospecific difference in the desorption energies of R- and S-3-MCHO has been used as the basis for demonstration of an enantioselective, kinetic separation of racemic 3-MCHO into its purified components during adsorption and desorption on the Cu(643)(R&S) surfaces.

Purpose: To evaluate the safety and efficacy of the Port Delivery System with ranibizumab (PDS) for neovascular age-related macular degeneration (nAMD) treatment.Design: Phase 2, multicenter, randomized, active treatmentecontrolled clinical trial.Participants: Patients diagnosed with nAMD within 9 months who had received 2 or more prior antievascular endothelial growth factor intravitreal injections and were responsive to treatment.Methods: Patients were randomized 3:3:3:2 to receive the PDS filled with ranibizumab 10 mg/ml, 40 mg/ml, 100 mg/ml, or monthly intravitreal ranibizumab 0.5-mg injections.Main Outcome Measures: Time to first implant refill assessed when the last enrolled patient completed the month 9 visit (primary efficacy end point), improvement in best-corrected visual acuity (BCVA) and central foveal thickness (CFT), and safety.Results: The primary analysis population was 220 patients, with 58, 62, 59, and 41 patients in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. Median time to first implant refill was 8.7, 13.0, and 15.0 months in the PDS 10-mg/ml, PDS 40-mg/ml, and PDS 100-mg/ml arms, respectively. At month 9, the adjusted mean BCVA change from baseline was -3.2 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, -0.5 ETDRS letters, þ5.0 ETDRS letters, and þ3.9 ETDRS letters in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. At month 9, the adjusted mean CFT change from baseline was similar in the PDS 100-mg/ml and monthly intravitreal ranibizumab 0.5-mg arms. The optimized PDS implant insertion and refill procedures were generally well tolerated. After surgical procedure optimization, postoperative vitreous hemorrhage rate was 4.5% (7/157; 1 event classified as serious). There was no evidence of implant clogging.Conclusions: In the phase 2 Ladder trial, the PDS was generally well tolerated and demonstrated a dose response across multiple end points in patients with nAMD. The PDS 100-mg/ml arm showed visual and anatomic outcomes comparable with monthly intravitreal ranibizumab 0.5-mg injections but with a reduced total number of ranibizumab treatments. The PDS has the potential to reduce treatment burden in nAMD while maintaining vision.

Temperature-programmed desorption (TPD) experiments have been conducted to investigate enantiospecific desorption from chiral single-crystal surfaces. The (643) and (six four three) planes of face-centered cubic metals such as Cu have kinked and stepped structures which are nonsuperimposable mirror images of one another and therefore are chiral. These chiral surfaces are denoted Cu(643)(R) and Cu(643)(S). We have observed that the desorption energies of (R)-3-methylcyclohexanone and (R)- and (S)-propylene oxides from the Cu(643)(R) and Cu(643)(S) surfaces depend on the relative handedness of the adsorbate/substrate combination. Since the (643) surface is comprised of terraces with local (111) orientation which are separated by kinked monatomic steps, it is instructive to perform TPD experiments with these chiral compounds on the achiral Cu(111) surface. These experiments have given some insight into the adsorption sites for the chiral molecules on the Cu(643) surfaces. There are several high-temperature features in the TPD spectra of the chiral compounds that only appear in the spectra from the (643) surfaces and thus are attributed to molecules adsorbed at or near the kinked steps. In addition there are lower temperature desorption features observed on the Cu(643) surfaces which occur in the same temperature range as desorption features observed on the Cu(111) surface. These features observed on the (643) surfaces are attributed to desorption from the flat (111) terraces.

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Chiral surfaces are of growing importance as a result of their potential for use in enantioselective chemical processes. By far the most widely used and commonly studied chiral surfaces are those prepared by templating of achiral surface with chiral organic ligands. It is possible, however, to prepare naturally chiral surfaces by a number of means. This paper describes the various types of chiral surfaces. In addition data are presented to suggest that naturally chiral surface of metals can be prepared by a process of imprinting in which chiral adsorbates induce reconstructions that create chiral kinks on metal surfaces.

The high Miller index planes of metal single crystals are chiral, if they do not lie perpendicular to any of the mirror symmetry planes of the bulk lattice. Such chiral surfaces of face-centered cubic metals expose kinked step edges and have been shown to have enantiospecific interactions with chiral adsorbates. R–3-methylcyclohexanone (R-3MCHO) exhibits enantiospecific differences in its desorption energies from the R and S chiral kinks on the Cu(643) R/S surfaces. This enantiospecific interaction must also manifest itself in the orientations of R-3MCHO adsorbed at chiral kinks and has been probed by examining the intensities of infrared absorption by R-3MCHO adsorbed at the kinks on the Cu(643) R/S surfaces. Fourier transform infrared reflection−absorption spectra show that the interaction of the R-3MCHO occurs through the carbonyl group which exhibits a red-shift in its stretching mode as a result of adsorption on the surface. The absorption intensities also indicate that the molecule is oriented with the >CO bond roughly parallel to the surface. More importantly, R-3MCHO adsorbed at the R and the S kinks on the Cu(643) R/S surfaces exhibits different relative absorption intensities of its vibrational modes, clearly indicating that the orientations of R-3MCHO are enantiospecific on the two enantiomorphic surfaces.

The desorption kinetics of a chiral compound, R-3-methylcyclohexanone (R-3MCHO), have been measured on both enantiomers of seven chiral Cu(hkl) surfaces and on nine achiral Cu single crystal surfaces with surface structures that collectively span the various regions of the stereographic triangle. The naturally chiral surfaces have terrace-step-kink structures formed by all six possible combinations of the three low Miller index microfacets. The chirality of the kink sites is defined by the rotational orientation of the (1 1 1), (1 0 0) and (1 1 0) microfacets forming the kink. R-3MCHO adsorbs reversibly on these Cu surfaces and temperature programmed desorption has been used to measure its desorption energetics from the chiral kink sites. The desorption energies from the R- and S-kink sites are enantiospecific, [Formula: see text], on the chiral surfaces. The magnitude of the enantiospecificity is [Formula: see text]  ≈  1 kJ mol on all seven chiral surfaces. However, the values of [Formula: see text] are sensitive to elements of the surface structure other than just their sense of chirality as defined by the rotational orientation of the low Miller index microfacets forming the kinks; [Formula: see text] changes sign within the set of surfaces of a given chirality.