PMC:7556614 / 36556-39402 JSONTXT

{"project":"2_test","denotations":[{"id":"33057878-24350328-28020","span":{"begin":1146,"end":1148},"obj":"24350328"},{"id":"33057878-24350328-28021","span":{"begin":2101,"end":2103},"obj":"24350328"}],"text":"Attenuated Total Reflection-Fourier Transform Infrared\nFigure 6 showed PEG 2000 characteristic peaks at 3409 cm−1 indicating intermolecular hydrogen-bonded hydroxyl group (O–H) asymmetric stretching. Peaks at 2945 cm−1, 2884 cm−1, and 2860 cm−1 are assigned to C–H symmetrical stretching. C–H bending is observed at 2740 cm−1 (42). Peaks at 1240 cm−1, 1146 cm−1, 1099 cm−1, and 1059 cm−1 are assigned to C–O–C stretching (43,44). Chitosan’s broad peak at 3354 cm−1 and 3291 cm−1 are indexed to NH2 stretching vibration. Peaks at 1651 cm−1 and 1585 cm−1 are assigned to N–H bending of primary amine. Peaks 1199 cm−1 and 1150 cm−1 are attributed to C–O stretching of C–O–C. Two intense peaks at 1058 cm−1 and 1026 cm−1 indicate the presence of primary aliphatic amine stretching of C–N overlapping with secondary cyclic alcohol stretching of O–H 1 (42,43,45). A peak at 894 cm−1 is attributed to the pyranoid ring of chitosan (46).\nFig. 6 Stacked spectra of ATR-FTIR from 4000 to 600 cm−1 for PALNs, physical mixture, acyclovir, lecithin, chitosan, and PEG 2000\nLecithin’ IR spectrum displays characteristic N–H group stretching at peak 3379 cm−1 (47). Symmetry stretching of C–H for the cis-double bond is depicted at 3009 cm−1. Saturated aliphatic ester carbonyl stretching (–C=O) is represented at peak 1735 cm−1 (48). A strong, sharp peak at 1087 cm−1 shows a symmetric stretching of phosphate groups (42). The asymmetric stretchings of P=O which overlapped with P–O where both co-exist in phosphodiester group, together with P–O–C stretching, were at peaks 1238 cm−1 and 1062 cm−1 respectively. The peak at 968 cm−1 is attributed to N+–(CH3)3 asymmetric stretching overlapped with O–P–O deformation (49). Out of plane bending of HC–CN is depicted at 818 cm−1 (50).\nAcyclovir IR spectrum shows intermolecular and intra-molecular hydrogen-bonded hydroxyl group (O–H) stretchings at 3515 cm−1 and 3470 cm−1 (51), while NH2 symmetrical stretching is at 3438 cm−1 (52). Secondary amine stretching is at 3290 cm−1 (42). A peak at 3177 cm−1 is attributed to N–H stretching overlapped with O–H stretching (47). C–H and H–C–H stretchings are represented at 2927 cm−1 and 2854 cm−1 (42). The presence of C=O at 1708 cm−1, presence of C8–H together with ring vibration of guanine, was shown at 1483 cm−1, while the presence of guanine structure was inferred at 1370 cm−1 (42).\nThe IR spectra of PM represent the combination of all characteristic peaks, such as 2884 cm−1 and 2860 cm−1 (PEG 2000); 3354 cm−1 and 3291 cm−1 (chitosan); 3379 cm−1 and 3009 cm−1 (lecithin); and 3470 cm−1, 3438 cm−1, and 3177 cm−1(ACV). The peaks showed very slight shifting (± 5 cm−1), indicating no bonding interaction between drug and other formulation ingredients. PALN1 was observed that none of the ACV characteristic peaks emerged, indicating encapsulation of the drug."}