Carbon-based nanomaterials are contemporary and are outpacing the technology platform. Graphene quantum dots (GQDs) had a significant impact on the subject of bioengineering, pharmaceuticals, biomedicine, biosensors, fuel, energy, etc. Depending on how quickly this field is developing, it is important to recognize the new difficulties that GQDs have to overcome. This is incredibly significant because many novel applications and innovations that have made GQD synthesis easier recently have not been systematically evaluated in prior studies. Their ability to combine the benefits of quantum dots, sp² carbon materials (large specific surface area), and have rich functional groups at the edge makes them special. The naturally occurring inert carbon helps to stabilize chemical and physical characteristics and makes significant advancements in the creation of benchmark photocatalysts. Moreover, current challenges and potential of these rapidly developing GQDs are emphasized. The future of GQD research is limitless, according to the assessment in this review, notably if future research focuses on simplicity of purification and ecofriendly synthesis. This feature article offers a realistic summary on recent developments in the synthesis, characteristics, and uses of GQDs. Frequent review articles focusing on the progress of GQDs for specific applications are published but a thorough review article on GQDs for their numerous uses has not yet been published. The recent trends of scientific research based on new optical biosensing applications, including the comprehensive applications of different zero-dimensional nanomaterials, specially GQDs are discussed in this study.

Antibiotic resistance is becoming more common, emphasising the demand for novel antibacterial treatments. The current investigation describes the green synthesis of graphene quantum dots (GQDs) using M. indica leaves and characterization via Fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and ultraviolet-visible (UV-Vis) spectrophotometer. The results showed that GQDs are spherical in shape. In vitro antioxidant and antimicrobial studies indicate that the biological efficacy of synthesized GQDs was higher than the ethanolic leaf extract. GQDs exhibited the highest scavenging efficacy with lowest IC₅₀ (half-maximal inhibitory concentration) value. However, antimicrobial study showed more inhibitory activity of GQDs against all screened microorganisms, i.e., Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, and fungi, i.e., Aspergillus niger and Aspergillus flavus. Graphene quantum dots facilitate reactive oxygen species (ROS) which ultimately lead to antioxidant and antibacterial activity. This approach would provide an efficient alternate method for tackling microorganisms.

Urease is an enzyme that plays a significant role in the hydrolysis of urea into carbonic acid and ammonia via the carbamic acid formation. The resultant increase in pH leads to the onset of various pathologies such as gastric cancer, urolithiasis, hepatic coma, hepatic encephalopathy, duodenal ulcers and peptic ulcers. Urease inhibitors can reduce the urea hydrolysis rate and development of various diseases. The Cinnamomum genus is used in a large number of traditional medicines. It is well established that stem bark of Cinnamomum cassia exhibits antiulcerogenic potential. The present study evaluated the inhibitory effect of seven extracts of Cinnamomum camphora, Cinnamomum verum and two pure compounds Camphene and Cuminaldehyde on urease enzyme. Kinetic studies of potential inhibitors were carried out. Methanol extract (IC₅₀ 980 µg/mL) of C. camphora and a monoterpene Camphene (IC₅₀ 0.147 µg/mL) possess significant inhibitory activity. The Lineweaver Burk plot analysis suggested the competitive inhibition by methanol extract, hexane fraction and Camphene. The Gas Chromatography-Mass Spectroscopy (GC–MS) analysis of hexane fraction revealed the contribution of various terpenes. The present study targets terpenes as a new class of inhibitors that have potential therapeutic value for further development as novel drugs.

In recent years, green synthesis methods for producing nanomaterials have gained significant interest due to their environmentally friendly nature and wide‐ranging applications. The present study addresses a novel green synthesis of graphene quantum dots (GQDs) using leaves of Withania somnifera. The size, morphology, and stability of the green‐synthesized GQDs were characterized using TEM, UV‐Visible spectroscopy, Fluorescence spectrophotometer, XRD, and DLS. The bio‐functional properties of the GQDs were investigated, with a focus on their antidiabetic and antioxidant capabilities. Their antidiabetic activity was assessed by examining their ability to inhibit α‐amylase and α‐glucosidase enzymes, which play a crucial role in glucose metabolism. Additionally, their antioxidant properties were evaluated using DPPH● scavenging assays, highlighting their effectiveness in neutralizing free radicals. The findings revealed that the synthesized GQDs outperformed the original leaf extract in both antioxidant activity and enzyme inhibition. The study revealed that the leaf extract exhibited higher IC ₅₀ values for inhibiting DPPH (78.508 ± 5.71), α‐amylase (161.909 ± 6.188), and α‐glucosidase (133.345 ± 7.328) compared to synthesized GQDs, which showed lower IC ₅₀ values of 72.74 ± 5.9, 137.966 ± 6.95, and 122.084 ± 5.478, respectively. The findings indicate that Withania somnifera derived GQDs hold significant potential for medical applications, warranting further investigation into their therapeutic efficacy. This study offers a comprehensive analysis of the fundamental biological properties of GQDs, addressing the dual challenges of antidiabetic and antioxidant activity.

The term ecosystem engineering focuses on how organisms physically change the abiotic environment and how this feeds back to the biota. Charles Darwin was the first naturalist who studied the role of the earthworms and their ecosystem services. Darwin’s last publication on earthworms gave the role of earthworms in global bioturbation. Darwin also used the word ‘friend of farmer’ and ‘nature ploughman’ for the earthworm because of its important role in the soil ecosystem. In modern ecological theory, bioturbation is recognised as ‘ecosystem engineering’. They are called as ecosystem engineers due to their different ecosystem services which cause the physical, chemical and biological changes in the soil. This review highlights the different ecological services provided by the earthworms that make them ecosystem engineers as said earlier by Darwin.

In recent years, the utilization of green synthesis routes for the production of nanomaterials has garnered considerable attention owing to their eco-friendly nature and multifaceted applications. Present study presents the phyto-mediated synthesis of red fluorescent graphene quantum dots using the leaves of Bauhinia variegata as a sustainable precursor. The synthesized GQDs were characterized through various analytical techniques i.e. UV–visible spectroscopy, FT-IR, fluorescence spectrophotometry, XRD, DLS and TEM to confirm their structural and optical properties. The bio-functional properties of the GQDs were explored, focusing on their antidiabetic and antioxidant activities. The antidiabetic potential of the GQDs was evaluated by measuring their inhibitory effects on α-amylase and α-glucosidase enzymes, which are key to glucose metabolism. Furthermore, antioxidant activity was assessed using DPPH^⋅ scavenging assays, demonstrating the free radical neutralizing ability of the GQDs. The study found that the synthesized graphene quantum dots (GQDs) were more effective than the leaf extract in antioxidant and enzyme inhibition activities. The GQDs showed lower IC₅₀ values for DPPH^⋅ radical scavenging (51.232 ± 6.478 µg/mL), α-amylase inhibition (135.309 ± 4.970 µg/mL), and α-glucosidase inhibition (147.551 ± 5.549 µg/mL) compared to the leaf extract, which showed higher IC₅₀ values of 71.157 ± 6.134 µg/mL, 157.660 ± 7.463 µg/mL, 152.455 ± 4.630 µg/mL respectively. The findings highlight the multifunctionality of Bauhinia derived GQDs as promising materials for biomedical and environmental applications, offering eco-friendly alternatives for antidiabetic treatments and antioxidant therapy.