Novel biosensor architecture based on nanocrystalline cellulose (NCC)/CdS quantum dots (QDs) nanocomposite was developed for phenol determination. This nanocomposite was prepared with slight modification of nanocrystalline cellulose (NCC) with cationic surfactant of cetyltriammonium bromide (CTAB) and further decorated with 3-mercaptopropionic acid (3-MPA) capped CdS QDs. The nanocomposite material was then employed as scaffold for immobilization of tyrosinase enzyme (Tyr). The electrocatalytic response of Tyr/CTAB-NCC/QDs nanocomposite towards phenol was evaluated using differential pulse voltammetry (DPV). The current response obtained is proportional to the concentration of phenol which attributed to the reduction of o-quinone produced at the surface of the modified electrode. Under the optimal conditions, the biosensor exhibits good linearity towards phenol in the concentration range of 5-40 μM (R2 = 0.9904) with sensitivity and limit of detection (LOD) of 0.078 μA/μM and 0.082 μM, respectively.

Nanotechnology-based drug delivery systems are an emerging technology for the targeted delivery of chemotherapeutic agents in cancer therapy with low/no toxicity to the non-cancer cells. With that view, the present work reports the synthesis, characterization, and testing of Mn:ZnS quantum dots (QDs) conjugated chitosan (CS)-based nanocarrier system encapsulated with Mitomycin C (MMC) drug. This fabricated nanocarrier, MMC@CS-Mn:ZnS, has been tested thoroughly for the drug loading capacity, drug encapsulation efficiency, and release properties at a fixed wavelength (358 nm) using a UV–Vis spectrophotometer. Followed by the physicochemical characterization, the cumulative drug release profiling data of MMC@CS-Mn:ZnS nanocarrier (at pH of 6.5, 6.8, 7.2, and 7.5) were investigated to have the highest release of 56.48% at pH 6.8, followed by 50.22%, 30.88%, and 10.75% at pH 7.2, 6.5, and 7.5, respectively. Additionally, the drug release studies were fitted to five different pharmacokinetic models including pesudo-first-order, pseudo-second-order, Higuchi, Hixson–Crowell, and Korsmeyers–Peppas models. From the analysis, the cumulative MMC release suits the Higuchi model well, revealing the diffusion-controlled mechanism involving the correlation of cumulative drug release proportional to the function square root of time at equilibrium, with the correlation coefficient values (R2) of 0.9849, 0.9604, 0.9783, and 0.7989 for drug release at pH 6.5, 6.8, 7.2, and 7.5, respectively. Based on the overall results analysis, the formulated nanocarrier system of MMC synergistically envisages the efficient delivery of chemotherapeutic agents to the target cancerous sites, able to sustain it for a longer time, etc. Consequently, the developed nanocarrier system has the capacity to improve the drug loading efficacy in combating the reoccurrence and progression of cancer in non-muscle invasive bladder diseases.

Nanocrystalline cellulose (NCC)/chitosan composite for immobilization of tyrosinase enzyme for the determination of phenol have been developed. The NCC/Chitosan composite film on screen printed carbon electrode (SPCE) was prepared by using drop casting technique. Characterization of the modified SPCE surface was investigated by using Transmission Electron Microscopy (TEM) and Fourier Transform Infrared (FTIR), respectively. Chronoamperometric (CA) technique is used to perform the electrochemical measurements. The detection of phenols by the developed system is derived on the direct electrochemical reduction of quinones produced by enzymatic reaction. The results demonstrated that the maximum response was observed at ratio of NCC/chitosan of 1 to 1 (v/v), tyrosinase concentration of 10 mg/mL and pH buffer of 7, respectively. It was found that the developed system gave linear response in the phenol concentration range of 0.39 -7.74 µM (slope = 28.316, R 2 = 0.9808) with the detection limit of 0.38 µM. The reproducibility of the system was also estimated and the Relative Standard Deviation (RSD) was found to be at 4.27%. Keywords: nanocrystalline cellulose, nanocomposite, immobilization, electrochemical, phenol AbstrakKomposit selulosa nanokristalin/kitosan untuk pemegunan enzim tirosinase bagi penentuan fenol telah dibangunkan. Filem komposit NCC/Chitosan di atas elektod karbon skrin bercetak (SPCE) telah disediakan melalui kaedah penyalutan acuan. Pencirian permukaan SPCE dimodifikasi dikaji menggunakan Mikroskop Elektron Transmisi (TEM) dan Transformasi Fourier Inframerah (FTIR). Teknik kronoamperometri (CA) digunakan untuk menjalankan pengukuran elektrokimia. Pengesanan fenol oleh sistem yang dibangunkan ini adalah berasaskan penurunan langsung elektrokimia oleh kuinon yang dihasilkan daripada tindak balas enzim. Keputusan menunjukkan bahawa rangsangan maksimum diperhatikan pada nisbah NCC/kitosan adalah 1 kepada 1 (v/v), kepekatan tirosinase 10 mg/mL dan larutan penimbal pada pH 7. Didapati bahawa sistem yang dibangunkan memberi rangsangan linear dalam julat kepekatan fenol 0.39-7.74 µM (kecerunan = 28.316, R 2 = 0.9808) dengan had pengesanan 0.38 µM. Kebolehulangan sistem juga telah dianggarkan dan nilai sisihan piawai relatif (RSD) yang diperolehi ialah 4.27%.Kata kunci: selulosa nanokristalin, nanokomposit, pemegunan, elektrokimia, fenol ISSN -2506 Fariza Aina et al: IMMOBILIZATION OF TYROSINASE IN NANOCRYSTALLINE CELLULOSE/CHITOSAN COMPOSITE FILM FOR AMPEROMETRIC DETECTION OF PHENOL 979Introduction Nanocrystalline cellulose (NCC) is a unique and sustainable nanomaterial obtained through acid hydrolysis of native cellulose, it has remarkable physical properties, such as biocompatibility, biodegradability and low toxicity as it originating from natural resources raw materials [1]. NCC has been studied to have a rigid rod-shape structure with 5 -10 nm in diameter and 10 -100 nm in length [2]. It can be extracted from native cellulose which is found in plants, animals and bacteria that composed of the ...

Cancer is one of the most devastating diseases that leads to a high degree of mortality worldwide. Hence, extensive efforts have been devoted to the development of drug nanocarrier vectors as a potential new cancer treatment option. The main goal of this treatment is to deliver an anticancer medicine successfully and effectively to the patient’s cells using non-toxic nanocarriers. Here, we present a drug delivery system to emphasize the optimization of an anticancer drug-loaded formulation using Mitomycin C (MMC) encapsulated in chitosan nanocarrier conjugated with a bioimaging fluorescence probe of Mn:ZnS quantum dots (MMC@CS-Mn:ZnS). Additionally, the Response Surface Methodology (RSM), which uses a quadratic model to forecast the behaviour of the nano-drug delivery system, was used to assess the optimization of encapsulation efficiency. In this investigation, the core points of the Central Composite Design (CCD) model were used with 20 runs and 6 replications. The encapsulation efficiency (EE%) was measured using UV-Vis spectroscopy at 362 nm. The highest EE% is 55.31 ± 3.09 under the optimum parameters of incubation time (105 min), concentration of MMC (0.875 mg/mL), and concentration of nanocarriers (5.0 mg/mL). Physicochemical characterizations for the nanocarriers were accessed using a nanosizer and field-emission scanning electron microscopy (FESEM). Three independent variables for the evaluation of the encapsulation efficiency were used, in which the incubation time, concentration of MMC, concentration of nanocarriers, and correlation for each variable were studied. Furthermore, the MMC drug release efficiency was carried out in four different solution pHs of 5.5, 6.0, 6.5, 7.0, and pH 7.5, and the highest cumulative drug release of 81.44% was obtained in a pH 5.5 release medium, followed by cumulative releases of 68.55%, 50.91%, 41.57%, and 32.45% in release mediums with pH 6.0, pH 6.5, pH 7.0, and pH 7.5. Subsequently, five distinct mathematical models—pseudo-first-order, pseudo-second-order, Hixson-Crowell, Korsmeyer-Peppas, and Higuchi kinetic models—were used to fit all of the drug release data. The Korsmeyers-Peppas model was found to fit it well, highlighting its importance for the log of cumulative drug release proportional to the log of time at the equilibrium state. The correlation coefficient value (R2) was obtained as 0.9527, 0.9735, 0.9670, 0.9754, and 0.9639 for the drug release in pH 5.5, pH 6.0, pH 6.5, pH 7.0, and pH 7.5, respectively. Overall, from the analysis, the as-synthesized MMC nanocarrier (MMC@CS-Mn:ZnS) synergistically elucidates the underlying efficient delivery of MMC and leverages the drug loading efficiency, and all these factors have the potential for the simultaneous curbing of non-muscle invasive bladder cancer reoccurrence and progression when applied to the real-time disease treatment.