Mobilization and health risk assessment of fertilizer induced uranium in coastal groundwater.

Uranium (U) in groundwater is hazardous to human health, especially if it is present in drinking water. The semiarid regions of southern India chiefly depend on groundwater for drinking purposes. In this regard, a comprehensive sampling strategy was adopted to collect groundwater representing different lithologies of the region. The samples were collected in two different seasons and analysed for major and minor ions along with total U in the groundwater. Two samples during pre monsoon (PRM) and seven samples during post monsoon (POM) had U > 30 µgL-1, which is above the World Health Organization's provisional guideline value. The high concentration of U (188 µgL-1) was observed in the alluvial formation though a few samples showed the release of U near the pink granite (39 µgL-1) and the concentration was low in the lateritic formation (10 µgL-1). The uranyl carbonato complexes UO2(CO3)22- and UO2(CO3)34- were associated with high pH which facilitated the transport of U into groundwater especially during POM. U3O8 is the major form observed in groundwater compared to either UO2 or UO3 in the both seasons. The uranium oxides were observed to be more prevalent at the neutral pH. Though U concentration increases with pH, it is mainly governed by the redox conditions. The principal component analysis (PCA) analysis also suggested redox conditions in groundwater to be the major process facilitating the U release mechanism regardless of the season. The POM season has an additional source of U in groundwater due to the application of nitrogenous fertilizers in the alluvium region. Furthermore, redox mobilization factor was predominantly observed near the coastal region and in the agricultural regions. The process of infiltration of the fertilizer-induced U was enhanced by the agricultural runoff into the surface water bodies in the region. Health risk assessment was also carried out by determining annual effective dose rate, cancer mortality risk, lifetime average daily dose and hazard quotient to assess the portability of groundwater in the study area. Artificial recharge technique and reducing the usage of chemical based fertilizers for irrigation are suggested as sustainable plans to safeguard the vulnerable water resource in this region.

Two-dimensional cancer theranostic nanomaterials: Synthesis, surface functionalization and applications in photothermal therapy.

In recent years, novel two-dimensional (2D) nanomaterials are of great interest for diverse potential applications such as device fabrication, energy storage, sensing and theranostics because of their superlative physical features namely, large surface area, minimal thickness, tunable composition and easier surface modification methods. Rapid exploration in design and fabrication of 2D nano-structures have opened new avenue for cancer theranostics as it can encapsulate group of cancer cells and inflict major damage with great specificity in a non-invasive manner. Among the reported 2D materials such as graphene and its derivatives, metallic compounds, transition metal dichalcogenides (TMDC), black phosphorous and MXenes (e.g., carbides, nitrides, or carbonitrides), 2D nanomaterials based on graphene and TMDCs have gathered most of the limelight in this field due to their easily tunable properties. In this review, we summarize recent progress in the design of 2D theranostic nanomaterials, functionalization methods and their applications in photothermal therapy (PTT) as well as synergistic cancer therapy. We have also addressed the different modes of cellular entry of 2D nanomaterials into tumor cells based on their unique structural properties and investigated different methodologies to enhance PTT effect by optimizing the physico-chemical properties of the 2D sheets. Recent progress on in vitro and in vivo short and long term biocompatibility, immunotoxicity and excretion of the decorated structure is also highlighted. Investigation of the interaction of 2D nanomaterial with hematological factors such as RBC and WBC is of paramount importance as they are key indicators in in vivo responses, and this investigation will give a better solution for overcoming direct inflammation and infection related issues of the animal system. Besides, investigations on addressing the ways to incorporate polymer linkers and drug conjugates on to the surface of 2D materials, multiplexing capability, and the influence of surface functionalization on PTT effect is vital for future developments in clinical level diagnosis and cancer therapy. Finally, we conclude our opinion on current challenges and future prospective on meeting the various demands of advanced cancer imaging and therapies.