Research Article Ribociclib-Loaded Ethylcellulose-Based Nanosponges: Formulation, Physicochemical Characterization, and Cytotoxic Potential against Breast Cancer Mohammed Muqtader Ahmed , 1 Farhat Fatima, 1 Amer Alali, 1 Mohd Abul Kalam , 2,3 Khalid Alhazzani, 4 Saurabh Bhatia, 5,6 Sultan Alshehri, 3 and Mohammed M. Ghoneim 7 1 Department of Pharmaceutics, College of Pharmacy, Prince Sattam Bin Abdulaziz University, PO Box 173, Al-Kharj 11942, Saudi Arabia 2 Nanobiotechnology Unit, Department of Pharmaceutics, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia 3 Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia 4 Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia 5 Natural and Medical Sciences Research Center, University of Nizwa, Birkat Al-Mauz, Oman 6 School of Health Science, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, India 7 Department of Pharmacy Practice, College of Pharmacy, AlMareefa University, Al-Diriyah 13713, Saudi Arabia Correspondence should be addressed to Mohammed Muqtader Ahmed; mo.ahmed@psau.edu.sa Received 18 January 2022; Revised 16 February 2022; Accepted 26 February 2022; Published 14 March 2022 Academic Editor: Lakshmipathy R Copyright © 2022 Mohammed Muqtader Ahmed et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In the present study, ribociclib-loaded nanosponges (RCNs) composed of ethylcellulose and polyvinyl alcohol were developed using an emulsion-solvent evaporation method. Preliminary evaluations of the developed RCNs (RCN1 to RCN7) were performed in terms of size, polydispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE), and drug loading (DL), which allowed us to select the optimized formulation. RCN3 was selected as the optimized carrier system with particle size (363:5±4:8 nm), PDI (0:292 ± 0:012), zeta potential (-18:5±0:05 mV), EE (81:35 ± 1:64%), and DL (21:96 ± 0:28%). Further, the optimized nanosponges (RCN3) were subjected to FTIR, XRD, DSC, and SEM studies, and results confirmed the proper encapsulation of the drug within the porous polymeric matrix. In vitro drug release studies showed that the drug release was significantly enhanced with a maximum drug release through RCN3 formulation (81:85 ± 0:37%) and followed the Higuchi model. Moreover, the RCN3 system showed greater cytotoxicity than free ribociclib (RC) against MDA-MB-231 and MCF-7 breast cancer cell lines. The percentage of apoptosis induced by RCN3 was found significantly higher than that of free RC (p <0:05). Overall, ribociclib-loaded ethylcellulose nanosponges could be a potential nanocarrier to enhance the effectiveness of ribociclib in breast cancer treatment. 1. Introduction Breast cancer (BC) is considered one of the most common and fatal cancer types detected in women globally [1–4]. It has been believed that BC is the second foremost reason for death after mortalities caused by lung cancer [4–8]. Cur- rent developments in explaining the molecular/cellular mechanisms associated with ER+ and TNBC, signaling path- ways, and cellular cycle controlling proteins have paved a path for merging endocrinotherapies with the targeted ther- apeutic agents [9–12]. Moreover, downregulation of cell pro- liferation is facilitated by unusual stimulation of the cellular cycle mechanism based on the biological effect of cyclin- dependent kinase (CDK) [13]. The development of Hindawi Adsorption Science & Technology Volume 2022, Article ID 1922263, 11 pages https://doi.org/10.1155/2022/1922263