Publications by authors named "Ahmed El-Hussein"

15 Publications

  • Page 1 of 1

The Prospective Beneficial Effects of Red Laser Exposure on Fermentation of Skim Milk.

Biology (Basel) 2020 Aug 31;9(9). Epub 2020 Aug 31.

The National Institute of Laser Enhanced Science, Cairo University, Giza 12613, Egypt.

Probiotic lactic acid bacteria are crucial producers of fermented dairy products that are popular functional foods in many countries. The health benefits of probiotic bacteria are mainly attributed to their effective bioactive metabolites. The quality of fermented milk is mainly dependent on the bacterial strain used in the fermentation process. In this study, an innovative technique is used in order to enhance the activities of the probiotic bacteria, quality of fermented milk, and consequently the whole fermentation process. Red laser dosages, at the wavelength of 632.7 nm, were applied to the type strain NRRL-B-1922 before the fermentation of skim milk. The results revealed that the scavenging of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and total antioxidant capacity were significantly increased from 21% in untreated control to 56% after bacterial laser irradiation of 12 J/cm dosage for 40 min. The antioxidant activity was found to be increased as the red laser dosage increased in a dose-response relationship. Additionally, the lactose fermentation in skim milk medium of 43.22 mg/mL initial concentration into organic acids was enhanced after irradiation and recorded 23.15 mg/mL compared to control group 28.35 mg/mL without bacterial pre-treatment. These results are correlated with increase of the β-Galactosidase activity, where the that has been exposed to 40 min of red laser exhibited the higher activity of a 0.37 unit/mL relative to the control 0.25 unit/mL. The assessment of this fermented milk after laser exposure for 10, 20, and 40 min indicates multiple biological effects, including assimilation of cholesterol as well as proteolytic and antibacterial activity. Our data on the exposure of to laser beam suggest promising application of red laser in the fermentation process of skim milk.
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http://dx.doi.org/10.3390/biology9090256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565532PMC
August 2020

Exploring optical spectroscopic techniques and nanomaterials for virus detection.

Saudi J Biol Sci 2021 Jan 27;28(1):78-89. Epub 2020 Aug 27.

Council for Scientific and Industrial Research (CSIR), National Laser Centre, P.O. Box 395, Pretoria 0001, South Africa.

Viral infections pose significant health challenges globally by affecting millions of people worldwide and consequently resulting in a negative impact on both socioeconomic development and health. Corona virus disease 2019 (COVID-19) is a clear example of how a virus can have a global impact in the society and has demonstrated the limitations of detection and diagnostic capabilities globally. Another virus which has posed serious threats to world health is the human immunodeficiency virus (HIV) which is a lentivirus of the retroviridae family responsible for causing acquired immunodeficiency syndrome (AIDS). Even though there has been a significant progress in the HIV biosensing over the past years, there is still a great need for the development of point of care (POC) biosensors that are affordable, robust, portable, easy to use and sensitive enough to provide accurate results to enable clinical decision making. The aim of this study was to present a proof of concept for detecting HIV-1 pseudoviruses by using anti-HIV1 gp41 antibodies as capturing antibodies. In our study, glass substrates were treated with a uniform layer of silane in order to immobilize HIV gp41 antibodies on their surfaces. Thereafter, the HIV pseudovirus was added to the treated substrates followed by addition of anti-HIV gp41 antibodies conjugated to selenium nanoparticle (SeNPs) and gold nanoclusters (AuNCs). The conjugation of SeNPs and AuNCs to anti-HIV gp41 antibodies was characterized using UV-vis spectroscopy, transmission electron microscopy (TEM) and zeta potential while the surface morphology was characterized by fluorescence microscopy, atomic force microscopy (AFM) and Raman spectroscopy. The UV-vis and zeta potential results showed that there was successful conjugation of SeNPs and AuNCs to anti-HIV gp41 antibodies and fluorescence microscopy showed that antibodies immobilized on glass substrates were able to capture intact HIV pseudoviruses. Furthermore, AFM also confirmed the capturing HIV pseudoviruses and we were able to differentiate between substrates with and without the HIV pseudoviruses. Raman spectroscopy confirmed the presence of biomolecules related to HIV and therefore this system has potential in HIV biosensing applications.
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http://dx.doi.org/10.1016/j.sjbs.2020.08.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449958PMC
January 2021

A Review of Chemotherapy and Photodynamic Therapy for Lung Cancer Treatment.

Anticancer Agents Med Chem 2021 ;21(2):149-161

Council for Scientific and Industrial Research (CSIR), National Laser Centre, Pretoria, South Africa.

Cancer is among the leading causes of mortality and morbidity worldwide. Among the different types of cancers, lung cancer is considered to be the leading cause of death related to cancer and the most commonly diagnosed form of such disease. Chemotherapy remains a dominant treatment modality for many types of cancers at different stages. However, in many cases, cancer cells develop drug resistance and become nonresponsive to chemotherapy, thus, necessitating the exploration of alternative and /or complementary treatment modalities. Photodynamic Therapy (PDT) has emerged as an effective treatment modality for various malignant neoplasia and tumors. In PDT, the photochemical interaction of light, Photosensitizer (PS) and molecular oxygen produces Reactive Oxygen Species (ROS), which induces cell death. Combination therapy, by using PDT and chemotherapy, can promote synergistic effect against this fatal disease with the elimination of drug resistance, and enhancement of the efficacy of cancer eradication. In this review, we give an overview of chemotherapeutic modalities, PDT, and the different types of drugs associated with each therapy. Furthermore, we also explored the combined use of chemotherapy and PDT in the course of lung cancer treatment and how this approach could be the last resort for thousands of patients that have been diagnosed by this fatal disease.
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http://dx.doi.org/10.2174/1871520620666200403144945DOI Listing
January 2021

Reduction of chromium-VI by chromium-resistant Escherichia coli FACU: a prospective bacterium for bioremediation.

Folia Microbiol (Praha) 2020 Aug 27;65(4):687-696. Epub 2020 Jan 27.

Department of Genetics, Faculty of Agriculture, Cairo University, Giza, 12613, Egypt.

The release of hexavalent chromium [Cr (VI)] into environments has resulted in many undesirable interactions with biological systems for its toxic potential and mutagenicity. Chromate reduction via chromium reductase (ChrR) is a key strategy for detoxifying Cr (VI) to trivalent species of no toxicity. In this study, ten bacterial isolates were isolated from heavily polluted soils, with a strain assigned as FACU, being the most efficient one able to reduce Cr (VI). FACU was identified as Escherichia coli based on morphological and 16S rRNA sequence analyses. Growth parameters and enzymatic actions of FACU were tested under different experimental conditions, in the presence of toxic chromium species. The E. coli FACU was able to reduce chromate at 100 μg/mL conceivably by reducing Cr (VI) into the less harmful Cr (III). Two distinctive optical spectroscopic techniques have been employed throughout the study. Laser-induced breakdown spectroscopy (LIBS) was utilized as qualitative analysis to demonstrate the presence of chromium with the distinctive spectral lines for bacteria such as Ca, Fe, and Na. While UV-visible spectroscopy was incorporated to confirm the reduction capabilities of E. coli after comparing Cr (III) spectrum to that of bacterial product spectrum and they were found to be identical. The chromate reductase specific activity was 361.33 μmol/L of Cr (VI) per min per mg protein. The FACU (EMCC 2289) 16S rRNA sequence and the ChrR-partially isolated gene were submitted to the DDBJ under acc. # numbers LC177419 and LC179020, respectively. The results support that FACU is a promising source of ChrR capable of bioremediation of toxic chromium species.
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http://dx.doi.org/10.1007/s12223-020-00771-yDOI Listing
August 2020

Amphiphilic tetracationic porphyrins are exceptionally active antimicrobial photosensitizers: In vitro and in vivo studies with the free-base and Pd-chelate.

J Biophotonics 2019 08 24;12(8):e201800318. Epub 2019 Apr 24.

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts.

Antimicrobial photodynamic inactivation (aPDI) employs the combination of nontoxic photosensitizing dyes and visible light to kill pathogenic microorganisms regardless of drug-resistance, and can be used to treat localized infections. A meso-substituted tetra-methylpyridinium porphyrin with one methyl group replaced by a C12 alkyl chain (FS111) and its Pd-derivative (FS111-Pd) were synthesized and tested as broad-spectrum antimicrobial photosensitizers when excited by blue light (5 or 10 J/cm ). Both compounds showed unprecedented activity, with the superior FS111-Pd giving 3 logs of killing at 1 nM, and eradication at 10 nM for Gram-positive methicillin-resistant Staphylococcus aureus. For the Gram-negative Escherichia coli, both compounds produced eradication at 100 nM, while against the fungal yeast Candida albicans, both compounds produced eradication at 500 nM. Both compounds could be categorized as generators of singlet oxygen (Φ = 0.62 for FS111 and 0.71 for FS111-Pd). An in vivo study was carried out using a mouse model of localized infection in a partial thickness skin abrasion caused by bioluminescent Gram-negative uropathogenic E. coli. Both compounds were effective in reducing bioluminescent signal in a dose-dependent manner when excited by blue light (405 nm), but aPDI with FS111-Pd was somewhat superior both during light and in preventing recurrence during the 6 days following PDT.
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http://dx.doi.org/10.1002/jbio.201800318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6646111PMC
August 2019

WITHDRAWN: An extremely low frequency-weak magnetic field can induce alterations in a biological system: A case study in chick embryo development.

Prog Biophys Mol Biol 2018 Oct 23. Epub 2018 Oct 23.

National Institute of Laser Enhanced Science, Cairo University, Egypt.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). These articles are retracted at the request of the authors. The joint Editors-in-Chief agree with this decision.
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http://dx.doi.org/10.1016/j.pbiomolbio.2018.10.005DOI Listing
October 2018

Progressive cationic functionalization of chlorin derivatives for antimicrobial photodynamic inactivation and related vancomycin conjugates.

Photochem Photobiol Sci 2018 May;17(5):638-651

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA. and Department of Dermatology, Harvard Medical School, Boston, Massachusetts 02115, USA and Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA.

It is known that multiple cationic charges are required to produce broad-spectrum antimicrobial photosensitizers (PS) for photodynamic inactivation (aPDI) or photodynamic therapy of bacteria and fungi. In the present study we describe the synthesis and aPDI testing of a set of derivatives prepared from the parent pheophytin molecule with different numbers of attached side arms (1-3) each consisting of five quaternized cationic groups (pentacationic), producing the corresponding [Zn2+]pheophorbide-a-N(C2N+C1C3)5 (Zn-Phe-N5+, 5 charges), [Zn2+]chlorin e6-[N(C2N+C1C3)5]2 (Zn-Chl-N10+, 10 charges) and [Zn2+]mesochlorin e6-[N(C2N+C1C3)5]3 (Zn-mChl-N15+, 15 charges). Moreover, a conjugate between Zn-Phe-N5+ and the antibiotic vancomycin called Van-[Zn2+]-m-pheophorbide-N(C2N+C1C3)5 (Van-Zn-mPhe-N5+) was also prepared. The aPDI activities of all compounds were based on Type-II photochemistry (1O2 generation). We tested these compounds against Gram-positive methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative Escherichia coli, and the fungal yeast Candida albicans. All three compounds were highly active against MRSA, giving eradication (≥6 logs of killing) with <1.0 μM and 10 J cm-2 of 415 nm light. The order of activity was Zn-Phe-N5+ > Zn-Chl-N10+ > Zn-mChl-N15+. In the case of E coli the activity was much lower (eradication was only possible with 50 μM Zn-mChl-N15+ and 20 J cm-2). The order of activity was the reverse of that found with MRSA (Zn-mChl-N15+ > Zn-Chl-N10+ > Zn-Phe-N5+). Activity against C. albicans was similar to E. coli with Zn-mChl-N15+ giving eradication. The activity of Van-Zn-mPhe-N5+ was generally lower than that of Zn-Phe-N5+ (except for E. coli). Red (660 nm) light was also effective as might be expected from the absorption spectra. An initial finding that Van-Zn-mPhe-N5+ might have higher activity against vancomycin resistant Enterococcus fecium (VRE) strains (compared to vancomycin sensitive strains) was disproved when it was found that VRE strains were also more sensitive to aPDI with Zn-Phe-N5+. The minimum inhibitory concentrations of Van-Zn-mPhe-N5+ were higher than those of Van alone, showing that the antibiotic properties of the Van moiety were lessened in the conjugate. In conclusion, Zn-Phe-N5+ is a highly active PS against Gram-positive species and deserves further testing. Increasing the number of cationic charges increased aPDI efficacy on C. albicans and Gram-negative E. coli.
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http://dx.doi.org/10.1039/c7pp00389gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5955822PMC
May 2018

Structure activity relationship studies on rhodanines and derived enethiol inhibitors of metallo-β-lactamases.

Bioorg Med Chem 2018 07 23;26(11):2928-2936. Epub 2018 Feb 23.

Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom. Electronic address:

Metallo-β-lactamases (MBLs) enable bacterial resistance to almost all classes of β-lactam antibiotics. We report studies on enethiol containing MBL inhibitors, which were prepared by rhodanine hydrolysis. The enethiols inhibit MBLs from different subclasses. Crystallographic analyses reveal that the enethiol sulphur displaces the di-Zn(II) ion bridging 'hydrolytic' water. In some, but not all, cases biophysical analyses provide evidence that rhodanine/enethiol inhibition involves formation of a ternary MBL enethiol rhodanine complex. The results demonstrate how low molecular weight active site Zn(II) chelating compounds can inhibit a range of clinically relevant MBLs and provide additional evidence for the potential of rhodanines to be hydrolysed to potent inhibitors of MBL protein fold and, maybe, other metallo-enzymes, perhaps contributing to the complex biological effects of rhodanines. The results imply that any medicinal chemistry studies employing rhodanines (and related scaffolds) as inhibitors should as a matter of course include testing of their hydrolysis products.
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http://dx.doi.org/10.1016/j.bmc.2018.02.043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6008492PMC
July 2018

Potentiation by potassium iodide reveals that the anionic porphyrin TPPS4 is a surprisingly effective photosensitizer for antimicrobial photodynamic inactivation.

J Photochem Photobiol B 2018 Jan 31;178:277-286. Epub 2017 Oct 31.

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA; Department of Dermatology, Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA. Electronic address:

We recently reported that addition of the non-toxic salt, potassium iodide can potentiate antimicrobial photodynamic inactivation of a broad-spectrum of microorganisms, producing many extra logs of killing. If the photosensitizer (PS) can bind to the microbial cells, then delivering light in the presence of KI produces short-lived reactive iodine species, while if the cells are added after light the killing is caused by molecular iodine produced as a result of singlet oxygen-mediated oxidation of iodide. In an attempt to show the importance of PS-bacterial binding, we compared two charged porphyrins, TPPS4 (thought to be anionic and not able to bind to Gram-negative bacteria) and TMPyP4 (considered cationic and well able to bind to bacteria). As expected TPPS4+light did not kill Gram-negative Escherichia coli, but surprisingly when 100mM KI was added, it was highly effective (eradication at 200nM+10J/cm of 415nm light). TPPS4 was more effective than TMPyP4 in eradicating the Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and the fungal yeast Candida albicans (regardless of KI). TPPS4 was also highly active against E. coli after a centrifugation step when KI was added, suggesting that the supposedly anionic porphyrin bound to bacteria and Candida. This was confirmed by uptake experiments. We compared the phthalocyanine tetrasulfonate derivative (ClAlPCS4), which did not bind to bacteria or allow KI-mediated killing of E. coli after a spin, suggesting it was truly anionic. We conclude that TPPS4 behaves as if it has some cationic character in the presence of bacteria, which may be related to its delivery from suppliers in the form of a dihydrochloride salt.
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http://dx.doi.org/10.1016/j.jphotobiol.2017.10.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771845PMC
January 2018

Recent Patents on Light-Based Anti-Infective Approaches.

Recent Pat Antiinfect Drug Discov 2018 ;13(1):70-88

Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States.

Background: Antibiotic resistance is one of the most serious health threats to modern medicine. The lack of potent antibiotics puts us at a disadvantage in the fight against infectious diseases, especially those caused by antibiotic-resistant microbial strains. To this end, an urgent need to search for alternative antimicrobial approaches has arisen. In the last decade, light-based anti-infective therapy has made significant strides in this fight to combat antibiotic resistance among various microbial strains. This method includes utilizing antimicrobial blue light, antimicrobial photodynamic therapy, and germicidal ultraviolet irradiation, among others. Light-based therapy is advantageous over traditional antibiotics in that it eradicates microbial cells rapidly and the likelihood of light-resistance development by microbes is low.

Methods: This review highlights the patents on light-based therapy that were filed approximately within the last decade and are dedicated to eradicating pathogenic microorganisms. The primary database that was used for the search was Google Patents. The searches were performed using the keywords including blue light, antimicrobial photodynamic therapy, ultraviolet irradiation, antibiotic resistance, disinfection, bacterium, fungus, and virus.

Results: Forty-five patents were obtained in our search: 9 patents for the antimicrobial blue light approach, 21 for antimicrobial photodynamic therapy, 11 for UV irradiation, and lastly 4 for other light-based anti-infective approaches. The treatments and devices discussed in this review are interestingly enough able to be used in various different functions and settings, such as dental applications, certain eye diseases, skin and hard surface cleansing, decontamination of internal organs (e.g., the stomach), decontamination of apparel and equipment, eradication of pathogenic microorganisms from buildings and rooms, etc. Most of the devices and inventions introduce methods of destroying pathogenic bacteria and fungi without harming human cells and tissues.

Conclusions: Light-based antimicrobial approaches hold great promise for the future in regards to treating antibiotic-resistant infections and related diseases.
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http://dx.doi.org/10.2174/1872213X11666171108104104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5938159PMC
December 2018

ROS generation and DNA damage with photo-inactivation mediated by silver nanoparticles in lung cancer cell line.

IET Nanobiotechnol 2017 Mar;11(2):173-178

Harvard-MIT Division of Health Sciences and Technology, Harvard and Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Lung cancer is considered one of the major health problems worldwide and the burden is even heavier in Africa. Nanomedicine is considered one of the most promising medical research applications nowadays. This is due to the unique physical and chemical properties of materials at the nanoscale. Silver nanoparticles have been extensively studied recently in many biomedical applications especially in cancer treatment, since they possess multifunctional effects that make these nanostructures ideal candidates for biomedical applications. AgNPs have been proved to have anti-tumour activity and the mode of cell death was shown to be apoptotic. The goal of the current work was to investigate the degree of DNA damage that may result from the usage of AgNPs as a photosensitiser in photo-inactivation and to evaluate the generation of reactive oxygen species (ROS) produced in the treatment. The results showed the occurrence of DNA damage in lung cancer cells (A549) through the generation of ROS shown by mitochondrial membrane potential changes.
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http://dx.doi.org/10.1049/iet-nbt.2015.0083DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505734PMC
March 2017

Potassium Iodide Potentiates Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal in and Studies.

Antimicrob Agents Chemother 2017 07 27;61(7). Epub 2017 Jun 27.

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA

Rose bengal (RB) is a halogenated xanthene dye that has been used to mediate antimicrobial photodynamic inactivation for several years. While RB is highly active against Gram-positive bacteria, it is largely inactive in killing Gram-negative bacteria. We have discovered that addition of the nontoxic salt potassium iodide (100 mM) potentiates green light (540-nm)-mediated killing by up to 6 extra logs with the Gram-negative bacteria and , the Gram-positive bacterium methicillin-resistant , and the fungal yeast The mechanism is proposed to be singlet oxygen addition to iodide anion to form peroxyiodide, which decomposes into radicals and, finally, forms hydrogen peroxide and molecular iodine. The effects of these different bactericidal species can be teased apart by comparing the levels of killing achieved in three different scenarios: (i) cells, RB, and KI are mixed together and then illuminated with green light; (ii) cells and RB are centrifuged, and then KI is added and the mixture is illuminated with green light; and (iii) RB and KI are illuminated with green light, and then cells are added after illumination with the light. We also showed that KI could potentiate RB photodynamic therapy in a mouse model of skin abrasions infected with bioluminescent .
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http://dx.doi.org/10.1128/AAC.00467-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5487662PMC
July 2017

N-dihydrogalactochitosan as a potent immune activator for dendritic cells.

J Biomed Mater Res A 2017 04 10;105(4):963-972. Epub 2017 Jan 10.

Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts 02114.

Immunotherapy has become one of the fastest growing areas of cancer research. A promising in situ autologous cancer vaccine (inCVAX) uses a novel immune activator, N-dihydrogalactochitosan (GC), that possesses the ability to stimulate dendritic cells (DC). inCVAX is a combination treatment procedure involving treatment of the tumor with a thermal near-infrared laser to liberate whole cell tumor antigens, followed by injection of GC (a glucosamine polymer with galactose attached to the amino groups) into the treated tumor thereby inducing a systemic antitumor immune response. Regression of both the treated tumor and distant untreated metastases has been observed in both nonclinical and clinical settings following inCVAX. We studied the stimulatory action of GC on relatively immature DCs (DC2.4 cell line) in vitro. GC at 1 mg/mL was a potent stimulator for DC with limited toxicity, giving increased expression of major histocompatibility complex class 2, CD80, and CD11c. Confocal imaging also revealed qualitatively increased uptake of antigen (Texas red-labeled ovalbumin) by DCs after the introduction of GC. To visualize cellular uptake, GC was conjugated with FITC-fluorophore revealing its cellular internalization after 8 hours. In some cases GC was more effective than the toxic TLR4 agonist, lipopolysaccharide. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 963-972, 2017.
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http://dx.doi.org/10.1002/jbm.a.35991DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328925PMC
April 2017

Comparative study between the photodynamic ability of gold and silver nanoparticles in mediating cell death in breast and lung cancer cell lines.

J Photochem Photobiol B 2015 Dec 2;153:67-75. Epub 2015 Sep 2.

Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein, South Africa.

Cancer is one of the dreadest diseases once diagnosed and has severe impacts on health, social and economic global aspects. Nanomedicine is considered an emerging approach for early cancer diagnosis and treatment. The multifunctional effects of silver and gold nanoparticles (Ag and Au NPs) have rendered them to be potent candidates for biomedical applications. The current work presents a comparative study between Au NPs and Ag NPs as possible potent photosensitizers (PS) in photodynamic therapy (PDT). Transmission electron microscopy (TEM) was used to identify and characterize the shape, size, and cellular localization of Au NPs; the absorption properties of Au NPs were determined using ultraviolet-visible spectroscopy (UV-Vis) and zeta potential was used to identify surface charge. Inverted light microscopy (LM), Trypan blue exclusion assay, adenosine triphosphate luminescence (ATP), and lactate dehydrogenase membrane integrity assays (LDH) were used for investigating the photodynamic ability of these nanostructures on breast (MCF-7) and lung (A549) cancer cell lines. Flow cytometry using Annexin V and propidium iodide (PI) dyes was used to determine the cell death pathway induced. The average size of the synthesized Au NPs was 50 nm, having an absorption peak at 540 nm with -7.85 mV surface net charge. MCF-7 and A549 cells were able to absorb the Au NPs. The latter, when irradiated with laser light in the phototherapeutic window, promoted cytotoxicity and a significant reduction in cell viability and proliferation were observed. The photodynamic activity that was observed in both cancer cell lines was found to be less eminent than that observed in case of the Ag NPs when compared to Au NPs. The present study is the first that compares the photodynamic ability of two different nanoparticles, silver and gold, as photosensitizers without any further functionalization. This study extends the possibilities of using such nanostructures in PDT within the therapeutic window wavelength, yet through the conjugation of Au NPs with other photosensitizers to synergize its effect.
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http://dx.doi.org/10.1016/j.jphotobiol.2015.08.028DOI Listing
December 2015

Sodium channels as gateable non-photonic sensors for membrane-delimited reactive species.

Biochim Biophys Acta 2014 May 7;1838(5):1412-9. Epub 2014 Feb 7.

Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena, & Jena University Hospital, Jena, Germany. Electronic address:

Reactive oxygen species (ROS) and reactive oxygen intermediates (ROI) play crucial roles in physiological processes. While excessive ROS damages cells, small fluctuations in ROS levels represent physiological signals important for vital functions. Despite the physiological importance of ROS, many fundamental questions remain unanswered, such as which types of ROS occur in cells, how they distribute inside cells, and how long they remain in an active form. The current study presents a ratiometric sensor of intracellular ROS levels based on genetically engineered voltage-gated sodium channels (roNaV). roNaV can be used for detecting oxidative modification that occurs near the plasma membrane with a sensitivity similar to existing fluorescence-based ROS sensors. Moreover, roNaV has several advantages over traditional sensors because it does not need excitation light for sensing, and thus, can be used to detect phototoxic cellular modifications. In addition, the ROS dynamic range of roNaV is easily manipulated in real time by means of the endogenous channel inactivation mechanism. Measurements on ROS liberated from intracellular Lucifer Yellow and genetically encoded KillerRed have revealed an assessment of ROS lifetime in individual mammalian cells. Flashlight-induced ROS concentration decayed with two major time constants of about 10 and 1000 ms.
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http://dx.doi.org/10.1016/j.bbamem.2014.01.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4083234PMC
May 2014