Nanoscale Probing of Liposome Encapsulating Drug Nanocrystal Using Atomic Force Microscopy-Infrared Spectroscopy

Abstract

Use of liposomes encapsulating drug nanocrystals for the treatment of diseases like cancer and pulmonary infections is gaining attention. The potential therapeutic benefit of these engineered formulations relies on maintaining the physical integrity of the liposomes and the stability of the encapsulated drug. With the significant advancement in the microscopic and analytical techniques, analysis of the size and size distribution of these nanosized vesicles is possible. However, due to the limited spatial resolution of conventional vibrational spectroscopy techniques, the chemical composition of individual nanosized liposome cannot be resolved. To address this limitation, we applied atomic force microscopy infrared spectroscopy (AFM-IR) to assess the chemical composition of individual liposomes encapsulating ciprofloxacin in dissolved and nanocrystalline form. Spatially resolved AFM-IR spectra acquired from individual liposomes confirmed the presence of peaks related to N–H bending vibration, C–N stretching and symmetric, and asymmetric vibration of the carboxyl group present in the ciprofloxacin. Our results further demonstrated the effectiveness of AFM-IR in differentiating the liposome containing ciprofloxacin in dissolved or nanocrystalline form. Spectra acquired from dissolved ciprofloxacin had peaks related to the ionised carboxyl group, i.e., at 1576 and 1392 cm–1, which were either absent or far weaker in intensity in the spectra of liposomal sample containing ciprofloxacin nanocrystals. These findings are highly significant for pharmaceutical scientists to ascertain the stability and physicochemical composition of individual liposomes and will facilitate the design and development of liposomes with greater therapeutic benefits.

Formulation and characterization of Ciprofloxacin encapsulated liposomes: in vitro antimicrobial activity against multi drug resistant Salmonella typhi

“…Tapping mode was used for the imaging of liposomal formulations in the current study because of their delicate nature. Same mode was applied for their imaging back in year 2020 (Khanal et al, 2020). Resultantly AFM results showed light and dark areas in the current study indicating a smooth surface texture for both liposomes and ciprofloxacin encapsulated liposomes.…”

Deciphering the Structure and Chemical Composition of Drug Nanocarriers: From Bulk Approaches to Individual Nanoparticle Characterization

“…The results were compared to cryo-TEM and AFM nanomechanical imaging where a uniform distribution was detected for the liquid drug whereas the crystalline form was located in the center of the liposomes. [122] Several other studies emphasize the high sensitivity of plasmon-enhanced PTIR where a polarized IR beam was used to determine the geometry and molecular orientation of drugs immobilized onto gold and silver NPs, such as a selective Y5 receptor antagonist, [123] α-methyl-DL-tryptophan, [124] erlotinib, [125,126] and nocodazole. [127] Additionally, PTIR also rises a significant interest for mapping organic NPs within cells.…”

“…The results were compared to cryo‐TEM and AFM nanomechanical imaging where a uniform distribution was detected for the liquid drug whereas the crystalline form was located in the center of the liposomes. [ 122 ]…”

Facile Method for Specifically Sensing Sphingomyelinase in Cells and Human Urine Based on a Ratiometric Fluorescent Nanoliposome Probe

“…Recently, liposomes have been applied in the field of biochemistry detection. − For example, Xue et al developed a target-controlled gating liposome for sensing phospholipase D activity in breast cancer cells . We once constructed a fluorophore-encapsulated nanoliposome (FEN) probe for sensing intracellular pH values .…”