# A Review of the Synthesis and Applications of Polymer-Nanoclay Composites
## 3 Application
### Biomedical Applications and Drug Delivery
Recently, a number of polymer/nanoclay composites have been developed as contrast agents for a variety of bioimaging techniques, including magnetic resonance imaging (MRI), photoacoustic (PA) imaging, fluorescence imaging (FI), and X-ray computed tomography (CT) scan, due to their impact on bio-distribution and pharmacokinetics [151]. [PERSON] et al. [192] developed a novel diagnostic agent using polydopamine/Fe\({}_{3}\)O\({}_{4}\) composites with promising properties such as high fluorescence quenching efficiency and near infrared absorption. It may be used in a variety of bioimaging systems including PA, MRI, and mRNA detection imaging. Due to their synergistic effects and hybrid properties, the development of polymer/nanoclay composite biosensors has gained significant interest in various applications [193], including food product analysis [194], the detection of human and animal pathogens [195], and environmental monitoring [196]. However, there are still some compatibility challenges in the implementation of polymer/nanoclay composites as a biosensor [197; 198; 199]. [PERSON] et al. [200] developed a convenient and fast biosensor to detect glucose in human whole blood using a graphene/PANI/AuNPs/ glucose oxidase enzyme (GOx) modified screen-printed carbon electrode (SPCE). The sensor is covered by sample-impregnated paper disks. Recently, [PERSON] et al. [201] incorporated platinum nanoparticles (PtNPs) into polymer/nanoclay composites for the direct sensing glucose, which have been used for blood glucose monitoring in human blood serum samples. Polymer/nanoclay composites have been developed to be effective vehicles for drug delivery [150]. They have efficient multifunctional properties needed for both targeting and controlling the delivery of the entrapped anticancer and antimicrobial drugs [202]. Biodegradable polymer/nanoclay composites loaded with anticancer agents can be tailored efficiently to deliver the desired therapeutic doses to target tissues/organs, thereby enhancing the agent's antitumor efficacy [203]. [PERSON] et al. [204] applied halloysite nanoclays as fillers in biodegradable poly(\(\epsilon\)-caprolactone) matrix and investigated the release mechanisms of sodium benzoate from the poly(\(\epsilon\)-caprolactone)/nanoclay composite. The addition of halloysite nanoclay enhanced the elastic modulus and mitigated the thermal degradation of the composites. The results showed that sodium benzoate molecules can be removed effectively via a washing procedure, thereby enabling the relatively accurate control of the drug's release kinetics from the composites. [PERSON] et al. [205] conducted an in-vitro drug release study of the controlled transdermal drug delivery of methylcellulose/pectin/MMT (MC/PEC/MMT) nanoclay composite films. The results showed that the rate of release of the drug decreases with the addition of pectin and nanoclay in methylcellulose matrix. The best performance, in terms of the controlled release of a transdermal drug, was achieved in the case of five wt% MMT-loaded MC/PEC/MMT nanoclay films. [PERSON] et al. [206] applied poly(D,L-lactide)/MMT nanoclay composites as drug carriers. The incorporation of  
Figure 6: Various biomedical applications of polymer/nanoclay composites. nanoclays into the poly(D,L-lactide) matrix improved both the drug loading capacity and the drug encapsulation efficiency. It also accelerated the rate of drug release into simulated intestinal fluid. Two wt% poly(D,L-lactide)/nanoclay was observed to be the most suitable drug carrier due to the spherical shape of the composites and the almost complete inclusion of the nanoclay platelets inside the host polymer. [PERSON] et al. [207] prepared a PP/MMT nanoclay composite fiber using the melt-spinning technique for Ibuprofen delivery. The prepared fiber was thermally stable, had improved mechanical properties, and low water absorption due to the high degree of homogeneity of the nanoclay in the polymer matrix.