###### Abstract  
Breast cancer (BC) ranks among the most diagnosed solid tumors worldwide. For decades, significant research efforts have been dedicated to finding selective treatments for these solid tumors. Currently, the primary treatment method for BC involves surgery, with the subsequent utilization of radiotherapy and chemotherapy. However, these subsequent treatments often fall short of effectively treating BC due to their side effects and harm to healthy tissues. Today, a range of nanoparticles are being developed to target BC cells without affecting the surrounding healthy tissues. This in-depth review, based on studies, seeks to shed light on these specially designed nanoparticles and their potential in BC treatment. Typically, therapeutic drugs or naturally occurring bioactive compounds are incorporated into precisely crafted nanoparticles. This enhances their solubility, longevity in the bloodstream, and distribution in the body while also minimizing side effects and immune reactions. Nanoparticles have been designed to address the shortcomings of standalone therapeutics and traverse various biological obstacles spanning the systemic, microenvironmental, and cellular that differ among patients and diseases. We prioritize breakthroughs in nanoparticle design to surpass diverse delivery obstacles and believe that smart nanoparticle engineering not only enhances effectiveness for general delivery but also allows customized solutions for specific needs, ultimately leading to better outcomes for patients. breast cancer; drug delivery; immunotherapy; nanomedicine; gene therapy 2024  
Applications and Future Directions. influence on the community. It is anticipated that the prolonged delays in diagnosis and treatment may lead to increased rates of severe disease and mortality [3]. The treatment approaches for breast cancer range from localized strategic treatments, like surgery and radiation, to systemic therapies, which encompass chemotherapy, immunotherapy, hormonal therapy, and endocrine therapy [4]. Disability and mortality rates are significantly influenced by cancer metastasis and recurrence, yet the precise underlying mechanisms remain unclear. Apart from the significant mortality associated with cancer, an enormous economic burden exists on both the families of cancer patients and society. Hence, prioritizing efforts toward cancer prevention, diagnosis, and treatment is of paramount importance. In cases of early-stage breast cancer, the effective form of treatment recommended is surgery. The objectives of breast cancer surgery include the pathological staging of both the tumor and axillary lymph nodes to offer crucial prognostic insights and full excision of the primary tumor with negative margins to limit the chance of local recurrences [4]. In instances of locally advanced breast cancer, neoadjuvant chemotherapy is administered to shrink the tumor in preparation for definitive surgery, potentially allowing for a less invasive procedure [5]. The effectiveness of neoadjuvant therapy in patients with triple-negative, which includes human epidermal growth factor receptor 2 (HER2), progesterone receptors, and estrogen receptors, helps to determine the best adjuvant therapy [6]. In breast cancer research, nanotechnology has proven to be effective for detection, diagnosis, and treatment. Numerous nanoformulations, including liposomes, nanofibers, nanocapsules, and nanoparticles, have been developed and investigated to inhibit breast cancer cell proliferation, prevent recurrence, and address postchemotherapy metastasis [7]. Research in nanotechnology for cancer therapy extends beyond conventional medication delivery, delving into the development of innovative medicines made possible by the distinctive characteristics of nanomaterials [5]. In addition, nanotechnology has successfully addressed the critical issue of nontargeted and nonspecific damage to bodily tissues resulting from conventional therapeutic measures.