Human exposure to airborne carbon nanotubes (CNT) is increasing because of their applications in different sectors; therefore, they constitute a biological hazard. Consequently, developing studies on CNT toxicity become a necessity. CNTs can have different properties in term of length, size and charge. Here, we compared the cellular effect of multiwall (MWCNTs) and single wall CNTs (SWCNTs). MWCNTs consist of multiple layers of graphene, while SWCNTs are monolayers. The effects of MWCNTs and SWCNTs were evaluated by the water‐soluble tetrazolium salt cell proliferation assay on NR8383 cells, rat alveolar macrophage cell line (NR8383). After 24 hours of exposure, MWCNTs showed higher toxicity (50% inhibitory concentration [IC 50 ] = 3.2 cm 2 /cm 2 ) than SWCNTs (IC 50 = 44 cm 2 /cm 2 ). Only SWCNTs have induced NR8383 cells apoptosis as assayed by flow cytometry using the annexin V/IP staining test. The expression of genes involved in oxidative burst ( Ncf1 ), inflammation ( Nfκb , Tnf‐α , Il‐6 and Il‐1β ), mitochondrial damage ( Opa ) and apoptotic balance ( Pdcd4 , Bcl‐2 and Casp‐8 ) was determined. We found that MWCNT exposure predominantly induce inflammation, while SWCNTs induce apoptosis and impaired mitochondrial function. Our results clearly suggest that MWCNTs are ideal candidates for acute inflammation induction. In vivo studies are required to confirm this hypothesis. However, we conclude that toxicity of CNTs is dependent on their physical and chemical characteristics.

The toxicity of heavy metals present in binary semiconductor nanoparticles also known as quantum dots (QDs) has hindered their wide applications hence the advent of non-toxic ternary quantum dots. These new group of quantum dots have been shown to possess some therapeutic action against cancer cell lines but not significant enough to be referred to as an ideal therapeutic agent. In this report, we address this problem by conjugating red emitting CuInS/ZnS QDs to a 5,10,15,20-tetrakis(3hydroxyphenyl)porphyrin-photosensitizer for improved bioactivities. The glutathione capped CuInS/ ZnS QDs were synthesized in an aqueous medium using a kitchen pressure cooker at different Cu: In ratios (1:4 and 1:8) and at varied temperatures (95 °C, 190 °C and 235 °C). Optical properties show that the as-synthesized CuInS/ZnS QDs become red-shifted compared to the core (CuInS) after passivation with emission in the red region while the cytotoxicity study revealed excellent cell viability against normal kidney fibroblasts (BHK21). The highly fluorescent, water-soluble QDs were conjugated to 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP) via esterification reactions at room temperature. The resultant water-soluble conjugate was then used for the cytotoxicity, fluorescent imaging and gene expression study against human monocytic leukemia cells (THP-1). Our result showed that the conjugate possessed high cytotoxicity against THP-1 cells with enhanced localized cell uptake compared to the bare QDs. In addition, the gene expression study revealed that the conjugate induced inflammation compared to the QDs as NFKB gene was over-expressed upon cell inflammation while the singlet oxygen (1 o 2) study showed the conjugate possessed large amount of 1 o 2 , three times than the bare porphyrin. Thus, the as-synthesized conjugate looks promising as a therapeutic agent for cancer therapy. The use of nanomaterials for biological application has in the past decade transpired as a promising avenue to explore for biological application due to their size, shape, specific surface area, aspect ratio and surface chemistry. Of the reported nanomaterial, semiconductor nanomaterials also known as quantum dots (QDs) still remain the most promising due to their excellent optoelectronic properties and spectral tunability which allows for their use in the ultraviolet and near infra-red region 1,2. These inherent properties have made QDs more appealing

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