## 1 Introduction  
Cancer is the second leading cause of death globally [1, 2]. It was the cause of death for an estimated 9.6 million people in 2018 [1, 2]. Based on projections, cancer deaths will continue to rise, with 13 million people projected to die of cancer in 2030. At this rate, cancer may surpass cardiovascular disease as the leading cause of death, globally [2]. Current scientific evidence suggests that cancer can be triggered by environmental and genetic factors [3]. Current treatment modalities include radiotherapy, chemotherapy, hormonal therapy, and surgical removal [4]. These conventional treatment modes, however, are known to induce multiple side effects that can have negative long-term effects on a patient's quality of life [4]. The emergence of drug delivery systems (DDS) for delivery of anticancer agents has created a profound impact on clinical therapeutics. DDS are used to deliver drugs to desired cells, tissues, organs, and subcellular organs for drug release and adsorption, through a variety of drug carriers [5]. In general, DDS are aimed at addressing some of the shortcomings of conventional cancer treatment methods, thereby improving treatment efficacy, while avoiding toxicity in normal cells. Their desirable features include improving the pharmaceutical activities of therapeutic drugs and alleviating the side effects of therapeutic drugs, thereby addressing the problem of low bioavailability, lack of selectivity, limited solubility, poor biodistribution, and drug aggregation [5]. Since the main aim of drug delivery is to attain and maintain the required therapeutic concentration of the drug in plasma, or at the site of action, for the period of treatment [6], controlled drug delivery presents several advantages. It reduces premature degradation, improves drug uptake, sustains drug concentrations within the therapeutic window, and reduces side effects associated with toxicity [7]. Hence, the concept of efficient drug delivery is important in disease management [8]. Over the past three decades, polymeric materials have played an important role in the controlled release of therapeutic agents over extended periods [9]. Due to their desirable characteristics, polymers are premier choices for localized, targeted, and controlled delivery of cancer drugs [9; 10]. Biodegradable polymeric drug delivery systems have also been used to achieve the controlled delivery of drugs, macromolecules, cells, and enzymes [11; 12; 13; 14]. Biopolymers have been used extensively in drug delivery applications. Their increased use is due to their biocompatibility and favorable degradation properties. These result in the breakdown of biopolymers to produce nontoxic byproducts [15; 16]. Prodigiosin (PGS) and paclitaxel (PTX) were used as our model drugs. PGS is a natural red pigment produced as a secondary metabolite by numerous bacterial species, which include _Serratia marcescens_, _Pseudomonas magnesium_, _Vibrio psychorevthrous_, _Serratia rubidaea_, _Vibrio gazogenes_, _Alteromonas rubra_, _Rugamonas rubra_, and Gram positive actinomycetes, such as _Streptoerticillium rubrireticuli_ and _Streptomyces longisporus ruber_[17; 18; 19; 20; 21]. Some members of the PGS family have antifungal, antimicrobial, antitumor, and immunosuppressive properties, and apoptotic effects in vitro [21; 22; 23; 24; 25]. PTX, also known as Taxol, is a natural product that was isolated from the year tree _Taxus brevifolia_[26; 27]. PTX is used as a chemotherapeutic agent and has been reported to have a broad spectrum of antitumor activity [27; 28]. To design controlled drug release systems for effective therapy, it is critical to understand drug release kinetics and thermodynamics. The kinetics of drug release conveys relevant knowledge about the function of material systems [29]. Mathematical models can be used to evaluate drug release mechanisms and kinetics [30].