Samina Nazir | National Centre for Physics, Islamabad (original) (raw)

Papers by Samina Nazir

Abstract: Human beings suffer from several infectious agents such as viruses, bacteria, and proto... more Abstract: Human beings suffer from several infectious agents such as viruses, bacteria, and protozoans. Recently, there has been a great interest in developing biocompatible nanostructures
to deal with infectious agents. This study investigated benign ZnCuO nanostructures that were visible-light-responsive due to the resident copper in the lattice. The nanostructures were synthesized through a size-controlled hot-injection process, which was adaptable to the surface ligation processes. The nanostructures were then characterized through transmission electron microscopy, X-ray diffraction, diffused reflectance spectroscopy, Rutherford backscattering, and photoluminescence analysis to measure crystallite nature, size, luminescence, composition, and band-gap analyses. Antiprotozoal efficiency of the current nanoparticles revealed the photodynamic
killing of Leishmania protozoan, thus acting as efficient metal-based photosensitizers. The crystalline nanoparticles showed good biocompatibility when tested for macrophage toxicity and in hemolysis assays. The study opens a wide avenue for using toxic material in resident nontoxic forms as an effective antiprotozoal treatment.
Keywords: zinc oxide, nanoparticles, doping, photodynamic therapy, Leishmania

Journal of Nanobiotechnology, 2014

Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention fo... more Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-β-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, α-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal. Results: The conjugation of AR to silver was confirmed through FTIR, UV-vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV-vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver. Conclusions: Our synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

European Journal of Organic Chemistry, 2011

ABSTRACT Several C-terminal peptidyl-substituted bis- and tris(electrophiles) were prepared by st... more ABSTRACT Several C-terminal peptidyl-substituted bis- and tris(electrophiles) were prepared by starting from polymeric phosphoranylidenacetates as acyl anion equivalents. After C-acylations with amino acids and peptide elongation, the obtained peptidyl-phosphoranylideneacetate resins were either cleaved oxidatively, delivering peptidyl-diketo esters, or saponified, leading to immediate decarboxylation. The generated peptidyl-phosphorane could be treated with aldehydes to yield peptidyl vinyl ketones or could be cleaved oxidatively to yield peptidyl keto aldehydes. Ligation with various bis(nucleophiles) including hydrazines, hydroxylamine, diamines, amino-thiols, amidines, and guanidines were investigated in the formation of peptide-heterocycle chimera containing pyrazoline, pyrazole, isoxazole, isoxazoline, thiazepine, quinoxaline, and imidazolone heterocycles.

Chemistry & Biodiversity, 2005

A 120-membered chalcone library has been designed and prepared from six differently substituted a... more A 120-membered chalcone library has been designed and prepared from six differently substituted acetophenones (A 1 ± A 6 ) and 20 benzaldehydes (B 1 ± B 20 ). The library was subjected to biological studies targeted against six bacterial strains. For the identification of the most-active member(s) of the library, the socalled indexed or positional-scanning method was applied. Six out of 26 sub-libraries, i.e., AL 1 ± AL 6 , were synthesized by keeping the acetophenone moiety A fixed and using equimolar quantities of the 20 different benzaldehydes. The remaining 20 sub-libraries BL 1 ± BL 20 were prepared by keeping the benzaldehyde B component fixed and varying the six acetophenones ( ). The bactericidal activities of the resulting sublibraries were tested and used as indices to the rows or columns of a two-dimensional matrix. Finally, parallel synthesis of 24 specific members with the highest-expected antibacterial activities, present in two sub-libraries, was carried out. These chalcones were screened again, and the results were exploited for establishing the structure ± activity relationship (SAR) and the identification of the lead compound, which turned out to be 1,3bis(2-hydroxyphenyl)prop-2-en-1-one (A 2 B 2 ) in terms of activity towards Staphylococcus aureus and Bacillus subtilis (Tables 5 ± 7).

Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention fo... more Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-β-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, α-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal. Results: The conjugation of AR to silver was confirmed through FTIR, UV-vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV-vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver. Conclusions: Our synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

The use of photoactive nanoparticles (NPs) such as zinc oxide (ZnO) and its nanocomposites has be... more The use of photoactive nanoparticles (NPs) such as zinc oxide (ZnO) and its nanocomposites has become a promising anticancer strategy. However, ZnO has a low photocatalytic decomposition rate and the incorporation of metal ions such as silver (Ag) improves their activity. Here different formulations of ZnO:Ag (1, 3, 5, 10, 20 and 30% Ag) were synthesized by a simple co-precipitation method and characterized by powder X-ray diffraction, scanning electron microscopy, Rutherford back scattering and diffuse reflectance spectroscopy for their structure, morphology, composition and optical band gap. The NPs were investigated with regard to their different photocatalytic cytotoxic effects in human malignant melanoma (HT144) and normal (HCEC) cells. The ZnO:Ag nanocomposites killed cancer cells more efficiently than normal cells under daylight exposure. Nanocomposites having higher Ag content (10, 20 and 30%) were more toxic compared to low Ag content (1, 3 and 5%). For HT144, under daylight exposure, the IC 50 values were ZnO:Ag (10%): 23.37 μg/mL, ZnO:Ag (20%): 19.95 μg/mL, and ZnO:Ag (30%): 15.78 μg/mL. ZnO:Ag (30%) was toxic to HT144 (IC 50 : 23.34 μg/mL) in dark as well. The three nanocomposites were further analyzed with regard to their ability to generate reactive oxygen species (ROS) and induce lipid peroxidation. The particles led to an increase in levels of ROS at cytotoxic concentrations, but only HT144 showed strongly induced MDA level. Finally, NPs were investigated for the ROS species they generated in vitro. A highly significant increase of 1 O 2 in the samples exposed to daylight was observed. Hydroxyl radical species, HO • , were also generated to a lesser extent. Thus, the incorporation of Ag into ZnO NPs significantly improves their photo-oxidation capabilities. ZnO:Ag nanocomposites could provide a new therapeutic option to selectively target cancer cells.

We describe daylight responsive silver (Ag) doped semiconductor nanoparticles of zinc oxide (DSNs... more We describe daylight responsive silver (Ag) doped semiconductor nanoparticles of zinc oxide (DSNs) for photodynamic therapy (PDT) against Leishmania. The developed materials were characterized by X-ray diffraction analysis (XRD), Rutherford backscattering (RBS), diffused reflectance spectroscopy (DRS), and band-gap analysis. The Ag doped semiconductor nanoparticles of zinc oxide were PEGylated to enhance their biocompatibility. The DSNs demonstrated effective daylight response in the PDT of Leishmania protozoans, through the generation of reactive oxygen species (ROS) with a quantum yield of 0.13 by nondoped zinc oxide nanoparticles (NDSN) whereas 0.28 by DSNs. None of the nanoparticles have shown any antileishmanial activity in dark, confirming that only ROS produced in the daylight were involved in the killing of leishmanial cells. Furthermore, the synthesized nanoparticles were found biocompatible. Using reactive oxygen species scavengers, cell death was attributable mainly to 77-83% singlet oxygen and 18-27% hydroxyl radical. The nanoparticles caused permeability of the cell membrane, leading to the death of parasites. Further, the uptake of nanoparticles by Leishmania cells was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). We believe that these DSNs are widely applicable for the PDT of leishmaniasis, cancers, and other infections due to daylight response.

The development of novel nanomaterials and their use in biomedicine has received much attention i... more The development of novel nanomaterials and their use in biomedicine has received much attention in recent years. Significant advances
have been made in the synthesis of nanomaterials with controlled geometry, physicochemical properties, surface charge, and surface tailoring
with bioactive polymers. These successful efforts have resulted in improved biocompatibility and active targeting of tumour tissues,
leading to the development of a diverse range of nanomaterials that can recognize cancers, deliver anticancer drugs and destroy tumours by a
variety of therapeutic techniques. The focus of this review is to provide an overview of the nanomaterials that have been devised for the
detection and treatment of various types of cancer, as well as to underline the emerging possibilities of nanomaterials for applications in
anticancer therapy.
From the Clinical Editor: In this comprehensive review, the current state-of-the art of nanomaterials for cancer diagnosis and treatment is
presented. Emerging possibilities and future concepts are discussed as well.
© 2014 Elsevier Inc. All rights reserved.

Abstract: Human beings suffer from several infectious agents such as viruses, bacteria, and proto... more Abstract: Human beings suffer from several infectious agents such as viruses, bacteria, and protozoans. Recently, there has been a great interest in developing biocompatible nanostructures
to deal with infectious agents. This study investigated benign ZnCuO nanostructures that were visible-light-responsive due to the resident copper in the lattice. The nanostructures were synthesized through a size-controlled hot-injection process, which was adaptable to the surface ligation processes. The nanostructures were then characterized through transmission electron microscopy, X-ray diffraction, diffused reflectance spectroscopy, Rutherford backscattering, and photoluminescence analysis to measure crystallite nature, size, luminescence, composition, and band-gap analyses. Antiprotozoal efficiency of the current nanoparticles revealed the photodynamic
killing of Leishmania protozoan, thus acting as efficient metal-based photosensitizers. The crystalline nanoparticles showed good biocompatibility when tested for macrophage toxicity and in hemolysis assays. The study opens a wide avenue for using toxic material in resident nontoxic forms as an effective antiprotozoal treatment.
Keywords: zinc oxide, nanoparticles, doping, photodynamic therapy, Leishmania

Journal of Nanobiotechnology, 2014

Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention fo... more Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-β-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, α-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal. Results: The conjugation of AR to silver was confirmed through FTIR, UV-vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV-vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver. Conclusions: Our synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

European Journal of Organic Chemistry, 2011

ABSTRACT Several C-terminal peptidyl-substituted bis- and tris(electrophiles) were prepared by st... more ABSTRACT Several C-terminal peptidyl-substituted bis- and tris(electrophiles) were prepared by starting from polymeric phosphoranylidenacetates as acyl anion equivalents. After C-acylations with amino acids and peptide elongation, the obtained peptidyl-phosphoranylideneacetate resins were either cleaved oxidatively, delivering peptidyl-diketo esters, or saponified, leading to immediate decarboxylation. The generated peptidyl-phosphorane could be treated with aldehydes to yield peptidyl vinyl ketones or could be cleaved oxidatively to yield peptidyl keto aldehydes. Ligation with various bis(nucleophiles) including hydrazines, hydroxylamine, diamines, amino-thiols, amidines, and guanidines were investigated in the formation of peptide-heterocycle chimera containing pyrazoline, pyrazole, isoxazole, isoxazoline, thiazepine, quinoxaline, and imidazolone heterocycles.

Chemistry & Biodiversity, 2005

A 120-membered chalcone library has been designed and prepared from six differently substituted a... more A 120-membered chalcone library has been designed and prepared from six differently substituted acetophenones (A 1 ± A 6 ) and 20 benzaldehydes (B 1 ± B 20 ). The library was subjected to biological studies targeted against six bacterial strains. For the identification of the most-active member(s) of the library, the socalled indexed or positional-scanning method was applied. Six out of 26 sub-libraries, i.e., AL 1 ± AL 6 , were synthesized by keeping the acetophenone moiety A fixed and using equimolar quantities of the 20 different benzaldehydes. The remaining 20 sub-libraries BL 1 ± BL 20 were prepared by keeping the benzaldehyde B component fixed and varying the six acetophenones ( ). The bactericidal activities of the resulting sublibraries were tested and used as indices to the rows or columns of a two-dimensional matrix. Finally, parallel synthesis of 24 specific members with the highest-expected antibacterial activities, present in two sub-libraries, was carried out. These chalcones were screened again, and the results were exploited for establishing the structure ± activity relationship (SAR) and the identification of the lead compound, which turned out to be 1,3bis(2-hydroxyphenyl)prop-2-en-1-one (A 2 B 2 ) in terms of activity towards Staphylococcus aureus and Bacillus subtilis (Tables 5 ± 7).

Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention fo... more Background: Conjugated and drug loaded silver nanoparticles are getting an increased attention for various biomedical applications. Nanoconjugates showed significant enhancement in biological activity in comparison to free drug molecules. In this perspective, we report the synthesis of bioactive silver capped with 5-Amino-β-resorcylic acid hydrochloride dihydrate (AR). The in vitro antimicrobial (antibacterial, antifungal), enzyme inhibition (xanthine oxidase, urease, carbonic anhydrase, α-chymotrypsin, cholinesterase) and antioxidant activities of the developed nanostructures was investigated before and after conjugation to silver metal. Results: The conjugation of AR to silver was confirmed through FTIR, UV-vis and TEM techniques. The amount of AR conjugated with silver was characterized through UV-vis spectroscopy and found to be 9% by weight. The stability of synthesized nanoconjugates against temperature, high salt concentration and pH was found to be good. Nanoconjugates, showed significant synergic enzyme inhibition effect against xanthine and urease enzymes in comparison to standard drugs, pure ligand and silver. Conclusions: Our synthesized nanoconjugate was found be to efficient selective xanthine and urease inhibitors in comparison to Ag and AR. On a per weight basis, our nanoconjugates required less amount of AR (about 11 times) for inhibition of these enzymes.

The use of photoactive nanoparticles (NPs) such as zinc oxide (ZnO) and its nanocomposites has be... more The use of photoactive nanoparticles (NPs) such as zinc oxide (ZnO) and its nanocomposites has become a promising anticancer strategy. However, ZnO has a low photocatalytic decomposition rate and the incorporation of metal ions such as silver (Ag) improves their activity. Here different formulations of ZnO:Ag (1, 3, 5, 10, 20 and 30% Ag) were synthesized by a simple co-precipitation method and characterized by powder X-ray diffraction, scanning electron microscopy, Rutherford back scattering and diffuse reflectance spectroscopy for their structure, morphology, composition and optical band gap. The NPs were investigated with regard to their different photocatalytic cytotoxic effects in human malignant melanoma (HT144) and normal (HCEC) cells. The ZnO:Ag nanocomposites killed cancer cells more efficiently than normal cells under daylight exposure. Nanocomposites having higher Ag content (10, 20 and 30%) were more toxic compared to low Ag content (1, 3 and 5%). For HT144, under daylight exposure, the IC 50 values were ZnO:Ag (10%): 23.37 μg/mL, ZnO:Ag (20%): 19.95 μg/mL, and ZnO:Ag (30%): 15.78 μg/mL. ZnO:Ag (30%) was toxic to HT144 (IC 50 : 23.34 μg/mL) in dark as well. The three nanocomposites were further analyzed with regard to their ability to generate reactive oxygen species (ROS) and induce lipid peroxidation. The particles led to an increase in levels of ROS at cytotoxic concentrations, but only HT144 showed strongly induced MDA level. Finally, NPs were investigated for the ROS species they generated in vitro. A highly significant increase of 1 O 2 in the samples exposed to daylight was observed. Hydroxyl radical species, HO • , were also generated to a lesser extent. Thus, the incorporation of Ag into ZnO NPs significantly improves their photo-oxidation capabilities. ZnO:Ag nanocomposites could provide a new therapeutic option to selectively target cancer cells.

We describe daylight responsive silver (Ag) doped semiconductor nanoparticles of zinc oxide (DSNs... more We describe daylight responsive silver (Ag) doped semiconductor nanoparticles of zinc oxide (DSNs) for photodynamic therapy (PDT) against Leishmania. The developed materials were characterized by X-ray diffraction analysis (XRD), Rutherford backscattering (RBS), diffused reflectance spectroscopy (DRS), and band-gap analysis. The Ag doped semiconductor nanoparticles of zinc oxide were PEGylated to enhance their biocompatibility. The DSNs demonstrated effective daylight response in the PDT of Leishmania protozoans, through the generation of reactive oxygen species (ROS) with a quantum yield of 0.13 by nondoped zinc oxide nanoparticles (NDSN) whereas 0.28 by DSNs. None of the nanoparticles have shown any antileishmanial activity in dark, confirming that only ROS produced in the daylight were involved in the killing of leishmanial cells. Furthermore, the synthesized nanoparticles were found biocompatible. Using reactive oxygen species scavengers, cell death was attributable mainly to 77-83% singlet oxygen and 18-27% hydroxyl radical. The nanoparticles caused permeability of the cell membrane, leading to the death of parasites. Further, the uptake of nanoparticles by Leishmania cells was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). We believe that these DSNs are widely applicable for the PDT of leishmaniasis, cancers, and other infections due to daylight response.

The development of novel nanomaterials and their use in biomedicine has received much attention i... more The development of novel nanomaterials and their use in biomedicine has received much attention in recent years. Significant advances
have been made in the synthesis of nanomaterials with controlled geometry, physicochemical properties, surface charge, and surface tailoring
with bioactive polymers. These successful efforts have resulted in improved biocompatibility and active targeting of tumour tissues,
leading to the development of a diverse range of nanomaterials that can recognize cancers, deliver anticancer drugs and destroy tumours by a
variety of therapeutic techniques. The focus of this review is to provide an overview of the nanomaterials that have been devised for the
detection and treatment of various types of cancer, as well as to underline the emerging possibilities of nanomaterials for applications in
anticancer therapy.
From the Clinical Editor: In this comprehensive review, the current state-of-the art of nanomaterials for cancer diagnosis and treatment is
presented. Emerging possibilities and future concepts are discussed as well.
© 2014 Elsevier Inc. All rights reserved.