Perspectives and advancements in the design of nanomaterials for targeted cancer theranostics

Highlights

• Cancer is one of the leading cause of death around the globe.

• Theranostics is a customised approach to cancer diagnosis.

• These nanomaterials can address cancer treatment issues and diagnostic challenges.

Abstract

Cancer continues to be one of the most challenging diseases to be treated and is one of the leading causes of deaths around the globe. Cancers account for 13% of all deaths each year, with cancer-related mortality expected to rise to 13.1 million by the year 2030. Although, we now have a large library of chemotherapeutic agents, the problem of non-selectivity remains the biggest drawback, as these substances are toxic not only to cancerous cells, but also to other healthy cells in the body. The limitations with chemotherapy and radiation have led to the discovery and development of novel strategies for safe and effective treatment strategies to manage the menace of cancer. Researchers have long justified and have shed light on the emergence of nanotechnology as a potential area for cancer therapy and diagnostics, whereby, nanomaterials are used primarily as nanocarriers or as delivery agents for anticancer drugs due to their tumor targeting properties. Furthermore, nanocarriers loaded with chemotherapeutic agents also overcome biological barriers such as renal and hepatic clearances, thus improving therapeutic efficacy with lowered morbidity. Theranostics, which is the combination of rationally designed nanomaterials with cancer-targeting moieties, along with protective polymers and imaging agents has become one of the core keywords in cancer research. In this review, we have highlighted the potential of various nanomaterials for their application in cancer therapy and imaging, including their current state and clinical prospects. Theranostics has successfully paved a path to a new era of drug design and development, in which nanomaterials and imaging contribute to a large variety of cancer therapies and provide a promising future in the effective management of various cancers. However, in order to meet the therapeutic needs, theranostic nanomaterials must be designed in such a way, that take into account the pharmacokinetic and pharmacodynamics properties of the drug for the development of effective carcinogenic therapy.

Introduction

Cancer is a complex disease that can affect any type of cells or tissues in the human body. It is observed through uncontrolled cell proliferation, where normal cells become a conglomeration of abnormal cells, forming a tumor or mass that can be in the form of either benign or malignant [[1], [2], [3], [4]]. The primary risk factors of cancer are unhealthy diet, prior family history, genetic mutations, ultraviolet (UV) radiation, drugs, occupational exposure, as well as tobacco use and alcohol consumption. There are several common types of cancer, such as the cancers of colon, lungs, brain, breast, blood, pancreas, nasopharyngeal and skin. These can be diagnosed by screening, imaging and laboratory testing [[5], [6], [7]]. Over the years, cancer has become one of the main causes of worldwide mortality despite the modern advancements in medical technologies. According to the World Health Organization (WHO), the global cancer burden has seen an increasing trend, in which it is estimated that there were 18.1 million new cancer cases in the year 2018. Besides, cancer is reported to be the second leading cause of death globally, accounting for approximately 9.6 million deaths in 2018 alone [8]. Currently, cancer therapies are only limited to radiotherapy, chemotherapy and surgical option. Nevertheless, all these treatment approaches pose inevitable risks of normal body tissues damage and incomplete eradication of cancer [9,10]. One such example is doxorubicin (DOX), one of the most common chemotherapeutic agents, whereby it induces apoptosis of rapidly dividing cells, at the same time killing several normal body cells that divides rapidly under normal circumstances [11]. Considering the high incidence, prevalence and mortality rate of cancer, it is evidently in need for medical researchers to develop an advanced technology for the safe and effective treatment of cancer [12].

Nanotechnology is a rapidly emerging field of scientific research that primarily involves in the know-how of the manufacturing, as well as the study of the structure, property and behaviour of materials that are sized in nanometers [[13], [14], [15], [16], [17], [18], [19]]. On the other hand, nanomedicine refers to the field where nanomaterials and nanotechnology are employed to design novel drug delivery systems to improve the efficacy of current therapeutics [[20], [21], [22], [23], [24], [25], [26]]. In cancer research, nanomedicine has remarkable potential to overcome the drawbacks of current chemotherapeutic agents. The rising interest on nanomedicine among cancer researchers can be attributed to the uniquely appealing properties of nanocarriers, namely their nanoscale size, promising drug release profile, high surface-to-volume ratio and most importantly, its ability to differentiate and selectively eradicate malignant cells [9,27]. Undoubtedly, nanomedicine has provided great insight in the design and engineering of a wide range of nanovehicles with varying sizes to improve therapeutic efficacy of the loaded chemotherapeutic agent, as well as achieving safety through specific targeting of tumor cells [28]. Moreover, the convergence of nanomedicine has also led to great efforts by medical researchers in the development of more advanced and innovative nanosystems that can deliver chemotherapeutic agents with specificity and monitor its therapeutic effectiveness at the same time [11]. Lim et al., discussed this hybrid nanotechnology where multiple materials were integrated in a multimodal system to establish multifunctional approaches to cancer treatment [29]. Madamsetty et al., illustrated recent developments in a variety of bio-inspired nanoparticles to tackle the limitations of traditional treatments for cancer. Moreover, because of its low cost, easy synthesis and low toxicity, bio-inspired nanoparticles carry an edge above conventionally synthesised nanoparticles [30]. This review discusses the various advantages of nanomaterials with respect to the pathophysiology of cancer, their molecular mechanisms, as well as several examples of nanomaterials currently applied in cancer therapy and their potentials to revolutionize the cancer medicine industry in the future.