Breast cancer develops whenabnormal breast epithelial cells begin to grow uncontrollably, leading to formation a tumor. Breast cancer typically originates in lobules of the breast or milk-carrying ducts (Libson and Lippman, 2014, Sharma et al., 2010). In 2020, approximately 2.3 million new instances of breast cancer were identified worldwide, and around 6,85000 individuals lost their lives to the illness. (Arnold et al., 2022). Approximately half of the breast cancer cases occurs in women with no identifiable risk factors other than age and gender . In men, the incidence of breast cancer ranges from 0.5 % to 1 %. In 2020, the two most prevalent cancers worldwide were lung and breast cancer, which accounted for 12.2 % and 12.5 % of all new cases, respectively (Ferlay et al., 2021). According to epidemiological research, the number of cases of breast cancer worldwide is expected to approach 2 million by 2030 (Zhang et al., 2024). Breast cancer has several subgroups and is a genetically and clinically complicated disease. The most common and generally recognized method of detecting breast cancer is immunohistochemistry, which is based on the hormonal receptors like Human epidermal growth receptor 2 (HER2) (Mitri et al., 2012), Progesterone (PR) (Li et al., 2022), and Estrogen (ER) (Zaha, 2014). Breast cancer can be detected by methods such as magnetic resonance imaging (MRI) (Mann et al., 2019), ultrasound (Sood et al., 2019), biopsy, genetic testing, blood biochemistry analysis, and self-examination (Jafari et al., 2018). Hormonal therapy, radiation therapy, immunotherapy, chemotherapy, surgery, and targeted therapy are among the treatments for breast cancer (Kutty et al., 2015, Maughan et al., 2010).

Indocyanine green (ICG) is a water-soluble cyanine dye and contains two benzoyl indoles (Alander et al., 2012, Lu and Hsiao, 2021). It has a 774.96 Dalton molecular weight. ICG has an emission range of 750–950 nm, with a maximum wavelength of 830 nm (Giraudeau et al., 2014). The maximal wavelength of ICG excitation in blood is 875 nm (Verma et al., 2024). With the deepest tissue penetration, it uses near-infrared (NIR) wavelengths for both excitation and emission. Consequently, ICG is widely utilized in molecular imaging across a range of in vivo animal models, owing to its well-characterized optical properties, excellent biocompatibility, and established performance in biological systems (Landsman et al., 1976, Refaat et al., 2022). A condensation polymer made of ethylene oxide and water is called polyethylene glycol (PEG) (Herzberger et al., 2016). It is utilized as emulsifying agents, plasticizers, etc. A useful and easily scalable technique for purifying viruses and exosomes is the precipitation of water-insoluble proteins with PEG (Ma et al., 2024).

Palbociclib (PLB) inhibits the phosphorylation of the retinoblastoma (Rb) protein by interacting reversibly with the cyclin-dependent kinases (CDK4 and CDK6). This inhibition blocks the transition from G1 to S phase of the cell cycle, thereby suppressing tumor cell proliferation. Estrogen receptors positive breast cancer cells are also targeted by PLB (Bilgin et al., 2017). It received FDA approval in 2015. It is clinically approved for treating patients having HER-2 negative, HR-positive and metastatic breast cancer (Dhillon, 2015).

Diacyl-chain phospholipids in aqueous solution self-assemble to form sphere-shaped or multilayered vesicles known as liposomes (Akbarzadeh et al., 2013). Liposomes size, hydrophilic and hydrophobic properties, and capacity to encapsulate molecules in both aqueous and lipophilic membranes make them a promising drug delivery vehicle (Eloy et al., 2014). The amount of lipids significantly influences the liposomes electrical charge, fluidity, stability, particle size, and stiffness (Nsairat et al., 2022). Because of its excellent drug loading efficiency, stability, bioavailability, safety, ease of manufacture, and biological compatibility, liposomes are utilized extensively in nanomedicine (Filipczak et al., 2020, Lombardo and Kiselev, 2022).

Exosomes are extracellular vesicles with an average diameter of 100 nm and a range of 30 to 150 nm. (Pegtel and Gould, 2019, Szatanek et al., 2017). Exosomes are produced when the plasma membrane successively invaginates, forming multivesicular entities that can interact with different intracellular vesicles and organelles (Schneider and Simons, 2013). Numerous physiological processes, such as tissue repair, development, and immune response modulation, are influenced by exosomes. Additionally, they contribute to pathological conditions like cancer, heart disease, and neurological disorders. (Kalluri and LeBleu, 2020, Qin and Xu, 2014). There are several ways to extract exosomes from biological fluids like blood, urine, saliva, cerebrospinal fluid, or cell culture supernatants, including size exclusion chromatography, immunoaffinity capture, density gradient centrifugation, precipitation, ultracentrifugation, and microfluidic-based techniques (Martins et al., 2023, Wu et al., 2019, Yang et al., 2019). The methodology used depends on the particular application and sample type, and each isolation method has pros and cons. Exosomes have elicited considerable interest in biomedical research and clinical settings due to their multifaceted roles in diagnostics, therapeutics, and prognostics (Chen et al., 2019, Chung et al., 2020). Exosomes based carriers offer promising advancements in precision diagnosis and targeted therapy by enabling efficient, biocompatible delivery of biomolecules (Wang et al., 2023).

Exosome and liposome hybrid nanoparticles combine the unique characteristics of both vesicle types to provide multipurpose delivery systems, representing a revolutionary approach to nanomedicine (Evers et al., 2022, Moholkar et al., 2023). Exosomes are usually enclosed within or adorn the surface of liposomes that have been loaded with therapeutic or imaging compounds to create hybrid exosome-liposome nanoparticles (Zhang et al., 2022). The exosome component contributes biological activity such as cell targeting and internalization capabilities, while the liposome offers a stable and biocompatible vesicle structure with controlled cargo release properties (Liu et al., 2022a). Cell-specific tropism, immunomodulatory effects, and the capacity to cross biological barriers are some of the intrinsic biological characteristics of exosomes (Huang et al., 2024). Hybrid exosome-liposome nanoparticles have demonstrated significant potential across several biomedical sectors, including drug delivery, gene therapy, regenerative medicine, and molecular imaging (Shafiei et al., 2021). They have been investigated for the targeted delivery of vaccines, anticancer drugs, RNA treatments, and contrast agents for imaging techniques such as fluorescence, MRI, and PET (Liu et al., 2025). By integrating NIR-II fluorescence imaging with drug delivery, exosome-based platforms have facilitated highly precise cancer theranostics (Muthu et al., 2014), offering improved targeted specificity and real-time monitoring of therapeutic processes (Roy et al., 2023). With advancements in exosome biology and liposome engineering, hybrid nanoparticles have demonstrated significant potential to revolutionize personalized therapeutics and precision medicine in the future (Mondal et al., 2023).

This study presents a novel hybrid nanovesicles platform formed through the fusion of exosomes and liposomes that combines the structural stability and adaptability of liposomes with the inherent biocompatibility and targeting capabilities of exosomes. To increase the efficacy of co-delivery methods for breast cancer theranostics, the fusion technique improves physicochemical stability, effectiveness of loading cargo, and sustained drug release thereby increasing the overall therapeutic efficacy. The integration of both imaging and therapeutic functionalities into the fused vesicle platform represents a novel dual-functionalization strategy, facilitating simultaneous diagnostic and therapeutic applications. Comprehensive physicochemical characterization including TEM, SEM, SPM, FTIR and encapsulation efficiency assessments alongside extensive in vitro evaluations such as cytotoxicity, cellular uptake, apoptosis, reactive oxygen species, and haemocompatibility, provides a robust validation of the platform’s performance. Importantly, the demonstration of enhanced intracellular delivery and mitochondria-mediated apoptosis underscores the therapeutic superiority of the fused vesicles over conventional formulations. Moreover, this study uniquely integrates advanced in vivo modalities for imaging, combining photoacoustic and ultrasound imaging to validate improved tumor targeting and accumulation via the synergistic effects of PEGylated liposomes and exosomal membrane components. The subsequent in vivo therapeutic assessment further establishes the fused vesicles capacity to suppress tumor growth, reduce hypoxia, and inhibit angiogenesis effectively. Collectively, this work introduces a pioneering nanotheranostic system that leverages exosome-liposome fusion to overcome limitations of existing drug delivery vehicles, offering a promising strategy for breast cancer theranostics with enhanced efficacy and biocompatibility.