Green synthesis of multi-functional carbon dots from medicinal plant leaves for antimicrobial, antioxidant, and bioimaging applications.

In this research work, carbon dots (CDs) were synthesized from the renewable leaves of an indigenous medicinal plant by the one-pot sand bath method, Azadirachta indica. The synthesized CDs were characterized for its optical properties using UV-Vis, Fluorescence and Fourier transform infrared (FT-IR) spectrophotometry and for structural properties using dynamic light scattering (DLS), X-ray Diffraction (XRD) and high resolution Transmission electron microscopy (HR-TEM). The synthesized CDs exhibited concentration dependent biocompatibility when tested in mouse fibroblast L929 cell line. The EC50 values of biomedical studies, free radical scavenging activity (13.87 µgmL-1), and total antioxidant capacity (38 µgmL-1) proved CDs were exceptionally good. These CDs showed an appreciable zone of inhibition when examined on four bacterial (two gram-positive and gram-negative) and two fungal strains at minimum concentrations. Cellular internalisation studies performed on human breast cancer cells (MCF 7- bioimaging) revealed the applicability of CDs in bioimaging, wherein the inherent fluorescence of CDs were utilised. Thus, the CDs developed are potential as bioimaging, antioxidants and antimicrobial agents.

Novel synthesis of fluorescent carbon dots from bio-based Carica Papaya Leaves: Optical and structural properties with antioxidant and anti-inflammatory activities.

Fluorescent carbon dots (CDs) are prepared from a natural resource Carica Papaya Leaves, by sand bath method. The as-synthesized CDs optical and structural properties were characterized by UltraViolet-Visible, FT- IR, and fluorescence spectroscopy. Also the size, shape, and particle size distribution was studied using Transmission electron microscopy technique. These CDs were examined for biomedical applications like free radical scavenging activity using DPPH assay, antioxidant activity using phosphomolybdate assay, and in vitro anti-inflammatory activity using membrane stabilization protocol. The CDs exhibited excellent biological activities at lower concentrations and showed notable half-maximal effective concentration (EC50). The EC50 of free radical scavenging activity (27.6 µg/mL), antioxidant activity (23.00 µg/mL), and in vitro anti-inflammatory activity (15.52 µg/mL) signifies that CDs can be potential therapeutic agents.

Sand bath assisted green synthesis of carbon dots from citrus fruit peels for free radical scavenging and cell imaging.

A sand bath assisted strategy for the synthesis of fluorescent carbon dots (CDs) using citrus fruit peels as a renewable green resource is reported in this work. The CDs were synthesized without any alkaline or acidic environment. The synthesized CDs were characterized by various spectroscopic and microscopy techniques. The CDs exhibited excellent water solubility and superior optical properties like excitation dependent emission, and multicolor fluorescence. In addition, the CDs have exhibited remarkable free radical scavenging activity (EC50: 4.7382 µg ml-1).The CDs were highly biocompatible and showed lower toxicity. The CDs when modified with folic acid have shown a significant potential as biological labels for cellular imaging at multiple excitations. Synthesis of CDs from natural fruit peels as an excellent carbon source for versatile applications has been demonstrated.

Manganese-doped green tea-derived carbon quantum dots as a targeted dual imaging and photodynamic therapy platform.

In this work, manganese-doped carbon quantum dots (Mn-CQDs) have been synthesized through a one-pot hydrothermal method by using waste green tea. The Mn2+ dopants were introduced to impart magnetic resonance capability. Upon optimization of the experimental conditions, magnetofluorescent Mn-CQDs exhibit an excitation-dependent blue emission. The abundant functional groups on Mn-CQDs not only promote water solubility but also allow straightforward functionalization with amine groups. The amine-terminated Mn-CQDs were then subsequently conjugated to folic acid (FA) and chlorin e6 (Ce6) to obtain the Mn-CQDs@FA/Ce6 magnetofluorescent photodynamic therapy (PDT) agent. in vitro studies using three different cells indicated specific targeting of Mn-CQDs@FA/Ce6 to the overexpressing folate receptor human epithelial carcinoma cell line (HeLa) cancer cells. Furthermore, Mn-CQDs@FA/Ce6 enhanced magnetic resonance imaging (MRI) signal with an r2 /r1 ratio of 5.77. Favorably, by using the Mn-CQDs@FA delivery system, active Ce6 can reach the cellular interior while its red fluorescence (FL) and reactive oxygen species generation can be retained, as has been verified by confocal microscopy. in vitro cell viability studies verified the biocompatibility of Mn-CQDs@FA/Ce6 nanohybrid with no significant toxicity up to 500 ppm while PDT treatment with 5 min irradiation (671 nm, 1 W cm-2 ) was effective in killing >90% of cells. The light-triggered Mn-CQDs@FA/Ce6 multifunctional hybrid can serve as a dual-modal FL/MRI probe and as an efficient PDT agent to detect and eradicate cancer cells remotely.

Graphene oxide@gold nanorods for chemo-photothermal treatment and controlled release of doxorubicin in mice Tumor.

Graphene oxide (GO) is a close derivative of graphene has unlocked many pivotal steps in drug delivery due to their inherent biocompatibility, excellent drug loading capacity, and shows antibacterial, antifungal properties etc. We used a novel plant material called Gum arabic (GA) to increase the solubility of GO as well as to chemically reduce it in the solution. GA functionalized GO (fGO) exhibited increased absorption in near infra-red region (NIR) which was exploited in photothermal therapy for cancer. In order to understand the shape and size effect of GO which may affect their rheological properties, we have conjugated them with gold nanorods (GNRs) using in situ synthesis of GO@GNRs via seed mediated method. To the above conjugate, Doxorubicin (DOX) was attached at ambient temperature (28±2°C). The release kinetics of DOX with the effect of NIR exposure was also carefully studied via in vitro photothermal killing of A549 cell lines. The enhancement in NIR induced drug release and photothermal property was observed which indicates that the fGO@GNRs-DOX method is an ideal choice for chemotherapy and photothermal therapy simultaneously.

Folic Acid navigated Silver Selenide nanoparticles for photo-thermal ablation of cancer cells.

Photothermal ablation of the cancer cells is a non-invasive technique for cancer treatment, involving cellular assassination in presence of photothermal agent. We are reporting silver selenide (Ag2Se) nanoparticles for photothermal therapy using folic acid for selective targeting. The material, when exposed to 808nm laser, the temperature got boosted to 54°C in 6.5min, thus proving its potential for photothermal ablation. The material was highly biocompatible (95%) at highest concentration (10µg/mL) against A 549 cells. However, in presence of laser, the cellular killing was 55%. The mode of death was analyzed using MALDI-TOF MS.