## 3 Results and Discussion  
### Fabrication and Analysis of the HNT-DAS-FA/FITC Complex  
After each synthetic step, an FTIR spectrum was obtained from the product. Upon sample inspection, IR analysis showed peeks associated with the grafting of the molecule DAS on the HNTs outer surface, and this result agrees with reported spectra published in previous studies. 42-46 Peeks of interest included N-H\({}_{2}\) scissoring at 1556 cm\({}^{-1}\), Si-CH deformation at 1329 cm\({}^{-1}\), and the bending associated with NH at 1654 cm\({}^{-1}\) as depicted in Figure 1 part b. Additionally, the 13C[H1]CPMAS showed aliphatic carbons associated with DAS and is illustrated in the supplemental information 2. The 13C[H1]CPMAS of unmodified HNTs is presented in supplemental information 1 for comparison.  
Upon conformation that the DAS was successfully grafted to the HNT surface, FA was tethered to the primary amine of the DAS via amide bond formation (Figure 1). The signals normally associated with the primary amine of DAS were reduced, and the appearance of a noisy signal between 1500-1300 cm\({}^{-1}\) was attributed to the attachment of FA to the DAS/HNT (Figure 2). In addition to the FTIR data, the 13C[H1]CPMAS spectrum showed the presence of carbonyl peeks as well as carbons associated with a conjugated ring. Additionally, after the HNT-DAS-FA was thoroughly washed to remove any unreacted material bound to the surface via weak interactions, a sample was exposed to 3 M NaOH to cleave the bonds tethering the FA to the surface of the HNTs. This reaction would release any compound chemically attached to the HNT surface remaining after the washing procedure. A solitary peek at 280.83 nm was observed in solution and is attributed to folic acid. Due to the reduction of the amine peaks, and the presence of only the folic acid after the wash phase, we conclude that folic acid had been successfully grafted to the DAS.  
Following successful formation of the HNT-DAS-FA complex, a fluorescent tag (FITC) was then added to the remaining DAS molecules that were not reacted with the FA in the previous step. Analysis of the sample via FTIR did not show a change from the last IR obtained of HNT-DAS-FA.  
However, upon decomposition of the samples with 3 M NaOH, both FA and FITC were present in the solution. It can be concluded that the FA was covalently bound to the DAS because it was not removed through washing or during the reaction with the FITC and subsequent washing process. Upon inspection of the 13C[H1]CPMAS of HNT-DAS-FA/FITC, little change was observed. This is not unexpected in that the carbons found in FITC are similar to those found in FA. Therefore, the peek positions would not change.  
The signals in both FTIR and 13C[H1]CPMAS were weak when compared to the spectra present in the literature [13]. However, when coupled with the FTIR data, our group concludes that the number of molecules capable of grafting to the surface of the HNTs is lower than that reported in other similar studies [42; 43; 44; 45]. In previously reported studies, the solvents used for the reaction were used to wash the compounds after the synthesis [42; 43; 44; 45]. While this would remove some excess material, this method is ineffective at removing the material bound to the surface of the HNTs that is deposited in layer-by-layer self-assembly [46; 47; 20]. This would lead to greater amounts of compounds being retained on the surface of the HNTs, and thus a larger signal for FTIR and NMR would result. The method for cleaning described would overcome this problem by removing any non-covalently bound compounds from the surface of the HNTs. Coupling the FTIR and NMR data the presence of the compounds post decomposition is evidence that the FITC and FA were covalently attached to the HNT surface (see Supplementary Materials data). Additionally, upon inspection of the ratio of FA to FITC fond in the decomposition of the final product, it was found to be approximately a 1:1 ratio that fits with our synthetic design.