Silver nanoparticles (AgNPs) are widely used in household products and in medicine due to their antibacterial and to wound healing properties. In recent years, there is also an effort for their use in biomedical imaging and photothermal therapy. The primary reason behind the effort for their utility in biomedicine and therapy is their unique plasmonic properties and easy surface chemistry for a variety of functionalizations. In this study, AgNPs modified with glucose, lactose, oligonucleotides and combinations of these ligands are investigated for their cytotoxicity and cellular uptake in living non-cancer (L929) and cancer (A549) cells. It is found that the chemical nature of the ligand strongly influences the toxicity and cellular uptake into the model cells. While the lactose-and glucose-modified AgNPs enter the L929 cells at about the same rate, a significant increase in the rate of lactose-modified AgNPs into the A549 cells is observed. The binding of oligonucleotides along with the carbohydrate on the AgNP surfaces influences the differential uptake rate pattern into the cells. The cytotoxicity study with the modified AgNPs reveals that only naked AgNPs influence the viability of the A549 cells. The findings of this study may provide the key to developing effective applications in medicine such as cancer therapy.

Proteins are one of the most versatile groups of molecules with vital functional roles in living systems. Their enormous diversity and structural flexibility make the detection of these molecules a challenging task. A simple and sensitive label-free protein detection method based on assembly of proteins and colloidal silver nanoparticles (AgNPs) on surfaces and surface-enhanced Raman scattering (SERS) is reported. The SERS spectra from the assembled AgNP/protein films show excellent reproducibility and high quality regardless of the proteins' charge status and size. A detection limit down to 0.5 μg/mL for three acidic proteins; BSA, catalase and pepsin, and three basic proteins; cytochrome c, avidin and lysozyme, is easily achieved. The minimum improvement in detection limit is more than 1 order of magnitude compared to the previously reported detection limits using the technique and the approach has the potential for label-free protein detection and identification.

The influence of the surface chemistry of silver nanoparticles (AgNPs) on p53 mediated cell death was evaluated using human dermal fibroblast (HDF) and lung cancer (A549) cells. The citrate reduced AgNPs (C-AgNPs) were modified with either lactose (L-AgNPs) or a 12-base long oligonucleotide (O-AgNPs). Both unmodified and modified AgNPs showed increased concentration and time dependent cytotoxicity and genotoxicity causing an increased p53 up-regulation within 6 h and led to apoptotic or necrotic cell deaths. The C-AgNPs induced more cytotoxicity and cellular DNA damage than the surface modified AgNPs. Modifying the C-AgNPs with lactose or the oligonucleotide reduced both necrotic and apoptotic cell deaths in the HDF cells. The C-AgNPs caused an insignificant necrosis in A549 cells whereas the modified AgNPs caused necrosis and apoptosis in both cell types. Compared to the O-AgNPs, the L-AgNPs triggered more cellular DNA damage, which led to up-regulation of p53 gene inducing apoptosis in A549 cells compared to HDF cells. This suggests that the different surface chemistries of the AgNPs cause different cellular responses that may be important not only for their use in medicine but also for reducing their toxicity.

Nuclear envelope (NE) proteins have fundamental roles in maintaining nuclear structure, cell signaling, chromatin organization, and gene regulation, and mutations in genes encoding NE components were identified as primary cause of a number of age associated diseases and cancer. Nesprin-1 belongs to a family of multi-isomeric NE proteins that are characterized by spectrin repeats. We analyzed NE components in various tumor cell lines and found that Nesprin-1 levels were strongly reduced associated with alterations in further NE components. By reducing the amounts of Nesprin-1 by RNAi mediated knockdown, we could reproduce those alterations in mouse and human cell lines. In a search for novel Nesprin-1 binding proteins, we identified MSH2 and MSH6, proteins of the DNA damage response pathway, as interactors and found alterations in the corresponding pathways in cells with lower Nesprin-1 levels. We also noticed increased number of γH2AX foci in the absence of exogenous DNA damage as was seen in tumor cells. The levels of phosphorylated kinases Chk1 and 2 were altered in a manner resembling tumor cells and the levels of Ku70 were low and the protein was not recruited to the DNA after hydroxyurea (HU) treatment. Our findings indicate a role for Nesprin-1 in the DNA damage response pathway and propose Nesprin-1 as novel player in tumorigenesis and genome instability.

Autosomal recessive primary microcephaly (MCPH) is a rare and heterogeneous genetic disorder characterized by reduced head circumference, low cognitive prowess and, in general, architecturally normal brains. As many as 14 different loci have already been mapped. We recruited 35 MCPH families in Pakistan and could identify the genetic cause of the disease in 31 of them. Using homozygosity mapping complemented with whole-exome, gene panel or Sanger sequencing, we identified 12 novel mutations in 3 known MCPH-associated genes - 9 in ASPM, 2 in MCPH1 and 1 in CDK5RAP2. The 2 MCPH1 mutations were homozygous microdeletions of 164,250 and 577,594 bp, respectively, for which we were able to map the exact breakpoints. We also identified four known mutations - three in ASPM and one in WDR62. The latter was initially deemed to be a missense mutation but we demonstrate here that it affects splicing. As to ASPM, as many as 17 out of 27 MCPH5 families that we ascertained in our sample were found to carry the previously reported founder mutation p.Trp1326*. This study adds to the mutational spectra of four known MCPH-associated genes and updates our knowledge about the genetic heterogeneity of MCPH in the Pakistani population considering its ethnic diversity.