This study investigated durian (Durio zibethinus) peels to produce powdered activated carbon (DPAC). The influence of process variables such as carbonization temperature, activation time, contact time, CO2 flow rate, and adsorption dosage was optimized using response surface methodology (RSM). A six-factor and two levels Box–Behnken design (BBD) was used to optimize the parameters. The independent variables were activation temperature (°C), duration (min), CO2 flow rate during the activation process (L/min), irradiation of adsorbent (kGy), irradiation duration (min), and adsorbent dosage (g) while phenol removal (mg/L) was the dependent variable (response). Following the observed correlation coefficient values, the design was fitted to a quadratic model (R2 = 0.9896). The optimal removal efficiency (97.25%) was observed at an activation temperature of 900 °C, activation time of 30 min, CO2 flow rate of 0.05 L/min, irradiation dose of 100 kGy, contact time of 35 min and adsorption dosage of 0.75 g. The optimal DPAC showed a BET surface of 281.33 m2/ g. The removal efficiency was later compared with a commercially available activated carbon which shows a 98.56% phenol removal. The results show that the durian peel could be an effective precursor for making activated carbon for phenol removal, and irradiation can significantly enhance surface activation.

Alzheimer's disease (AD) is one of the most common forms of dementia, affecting more than 50 million people globally. The onset of AD is linked to age, smoking, obesity, hypercholesterolemia, physical inactivity, depression, gender, and genetics of an individual. The accumulation of Aβ peptides and neurofibrillary tangles (NFTs) in the brain is one of the critical factors that lead to AD, which is known to disrupt neuronal signaling and causing neurodegeneration. As per the current understanding, inhibiting the accumulation of Aβ peptides and NFTs is crucial in the management/treatment of AD. Latest research studies show that nanoparticles have the potency of improving drug transport across the blood–brain barrier easily. Specifically, graphene quantum dots (GQDs), a type of semiconducting nanoparticles, have been established as effective inhibitors for blocking the aggregation of Aβ peptides. The small size of GQDs allows them to pass through the blood– brain barrier with ease. Moreover, GQDs have fluorescence properties, which can be used to detect the concentration of Aβ in vivo. In recent years, compared to other carbon materials, the low cytotoxicity and high biocompatibility of GQDs, give them an advantage in the suitability and clinical research for AD. In this manuscript, we have discussed the role of different types of nanoparticles in the transportation of encapsulated or co-assembled compound drugs for the treatment of AD and importantly, the role of GQDs in the diagnosis and management/treatment of AD.