Surface Plasmon Resonance Peak Research Articles

Photochemical preparation, characterization and formation kinetics of riboflavin conjugated silver nanoparticles

Riboflavin conjugated silver nanoparticles (RF–AgNPs) have been synthesized by photoreduction of Ag+ ions and characterized by UV–visible, X-ray diffraction (XRD), FTIR spectroscopy, spectrofluorimetry, dynamic light scattering (DLS) and atomic force microscopy (AFM). The RF–AgNPs exhibit a typical surface plasmon resonance (SPR) peak at 422 nm due to the interaction of RF and AgNPs. FTIR studies indicate the appearance of an intense absorption peak at 2920 cm–1 due to the interaction of RF and Ag. AFM studies indicate that the RF–AgNPs are spherical and polydisperse in nature (57–73 nm), which nicely complement the hydrodynamic radii (57.9–72.2 nm) measured by DLS. None of the tested concentrations (1-250 µg mL−1) of RF–conjugated AgNPs show any adverse effect on normal mouse fibroblast and cancerous non-small lung carcinoma cell lines. At acidic pH (2.0–6.2) aggregation of RF–AgNPs occurs due to an increase in the ionic strength of the medium. The rates of formation of RF–AgNPs on UV and visible light irradiation have been determined in the pH range of 8.0–10.5 and at different concentrations of Ag+ ions. The photochemical formation of RF–AgNPs follows a biphasic first–order reaction probably due to the formation of AgNPs in the first phase (fast) and the adsorption of RF on AgNPs to yield RF–AgNPs in the second phase (slow).

Naringenin-Capped Silver Nanoparticles Amalgamated Gel for the Treatment of Cutaneous Candidiasis.

The current research was aimed to synthesize a phytomolecule, naringenin (NRG)-mediated silver nanoparticles (NRG-SNPs) to study their antifungal potential against Candida albicans (C. albicans) and Candida glabrata (C. glabrata). The NRG-SNPs were synthesized by using NRG as a reducing agent. The synthesis of NRG-SNPs was confirmed by a color change and surface plasmon resonance (SPR) peak at 425nm. Furthermore, the NRG-SNPs were analyzed for size, PDI, and zeta potential, which were found to be 35 ± 0.21nm, 0.19 ± 0.03, and 17.73 ± 0.92mV, respectively. In silico results demonstrated that NRG had a strong affinity towards the sterol 14α-demethylase. The docking with ceramide revealed the skin permeation efficiency of the NRG-SNPs. Next, the NRG-SNPs were loaded into the topical dermal dosage form (NRG-SNPs-TDDF) by formulating a gel using Carbopol Ultrez 10 NF. The MIC50 of NRG solution and TSC-SNPs against C. albicans was found to be 50µg/mL and 4.8µg/mL, respectively, significantly (P < 0.05) higher than 0.3625µg/mL of NRG-SNPs-TDDF. Correspondingly, MIC50 results were calculated against C. glabrata and the results of NRG, TSC-SNPs, NRG-SNPs-TDDF, and miconazole nitrate were found to be 50µg/mL, 9.6µg/mL, 0.3625µg/mL, and 3-µg/mL, respectively. Interestingly, MIC50 of NRG-SNPs-TDDF was significantly (P < 0.05) lower than MIC50 of miconazole nitrate against C. glabrata. The FICI (fractional inhibitory concentration index) value against both the C. albicans and C. glabrata was found to be 0.016 and 0.011, respectively, which indicated the synergistic antifungal activity of NRG-SNPs-TDDF. Thus, NRG-SNPs-TDDF warrants further in depth in vivo study under a set of stringent parameters for translating in to a clinically viable antifungal product.

In-situ monitoring of plasmon-induced nanoscale photocatalytic activity from Au-decorated TiO2 microflowers

Noble-metal-decorated semiconductor photocatalysts have attracted noticeable attention due to their enhanced photocatalytic activity. Herein, we have synthesized the pure rutile phase of TiO2 nanorods, with microflower morphology, using a hydrothermal method and decorated them with Au to observe plasmon-induced enhanced photocatalytic efficiency. The optical bandgap engineering through Au-decorated TiO2 introduces midgap states that help with charge compensation during photodegradation studies. The surface plasmonic resonance peak of Au is observed together with the defect peak of TiO2, extending the absorption of the solar spectrum from the UV to the visible region. The quenching in photoluminescence intensity with increased Au thickness indicates the formation of a Schottky junction at the interface of Au and TiO2 that helps to reduce photogenerated charge carrier recombination. The softening of the E g Raman mode and photothermal effects originate from the nonradiative decay of localized surface plasmons through electron–phonon and phonon–phonon relaxation. The photocatalytic degradation of Rhodamine 6G is monitored by exposing the sample to UV and visible light sources under Raman spectroscopy. The Au decoration plays a crucial role in promoting charge separation, Schottky junction creation, photothermal effects, and UV to visible light absorption to enhance photocatalytic activity, which can be explained on the basis of the charge transfer mechanism. Our in-situ photodegradation study at the interface of noble metal and semiconducting materials will pave the way toward improving the understanding of plasmon-enhanced photocatalytic applications.

Au@Ag Nanopencil with Au Tip and Au@Ag Rod: Multimodality Plasmonic Nanoprobe based on Asymmetric Etching for the Detection of SCN- and ClO.

In this paper, Au@Ag nanopencil is designed as a multimodality plasmonic nanoprobe based on asymmetric etching for the detection of SCN- and ClO- . Au@Ag nanopencil with Au tip and Au@Ag rod is prepared by asymmetric tailoring of uniformly grown silver-covered gold nanopyramids under the combined effect of partial galvanic replacement and redox reaction. By asymmetric etching in different systems, Au@Ag nanopencil exhibits diversified changes in the plasmonic absorption band: O2 •- facilitated by SCN- etches Au@Ag rod from the end to the tip, causing a blue shift of the localized surface plasmon resonance (LSPR) peak as the aspect ratio decreases; while the ClO- can retain Au@Ag shell and etch Ag within rod from the tip to the end, causing a redshift of the LSPR peak as the coupling resonance weakens. Based on peak shifts in different directions, a multimodality detection of SCN- and ClO- has been established. The results demonstrate the detection limits of SCN- and ClO- are 160 and 6.7nm, and the linear ranges are 1-600µm and 0.05-13µm, respectively. The finely designed Au@Ag nanopencil not only broadens the horizon of designing heterogeneous structures, but also enriches the strategy of constructing multimodality sensing platform.

Color-encoded Escherichia coli assay via enzyme-induced etching of Au@MnO2 nanoparticles

Au@MnO2 nanoparticles (NPs), as core–shell nanostructures, have been widely used in ions, molecules and enzyme activities detection due to their stable properties and easy preparation, but their application in bacterial pathogens detection is rarely reported. In this work, Au@MnO2 NPs is employed for Escherichia coli (E. coli) detection through monitoring and measuring β-galactosidase (β-gal) activity based enzyme-induced color-code single particle enumeration (SPE) method. In the existence of E. coli, p-aminophenylβ-D-galactopyranoside (PAPG) can be hydrolyzed to generate p-aminophenol (AP) by the endogenous β-gal of E. coli. MnO2 shell reacts with AP and produces Mn2+, causing the blue shift of the localized surface plasmon resonance (LSPR) peak and color change of the probe from bright yellow to green. With the SPE method, the amount of E. coli can be quantified readily. The detection limit reaches 15 CFU/mL with dynamic range from 100 to 2900 CFU/mL. Besides, this assay is effectively employed to monitor E. coli in river water sample. The designed sensing strategy provides an ultrasensitive and low cost way for E. coli detection and has the possibility to detect other bacteria in environmental monitoring and food quality analysis.

Silver-osmium core-shell nanoparticles: Synthesis and heterogeneous persulfate activator

A simple route for the synthesis of cetyltrimethylammonium bromide (CTAB) immobilized silver-osmium hydrosols (Ag0–Os0) has been reported by using seedless chemical reduction. The Os0 nanoparticles (blue color hydrosols) were prepared with osmium(III) reduction by sodium borohydride in presence of (CTAB). The surface Plasmon resonance (SPR) peak position of Os0 was observed at 585 nm in an alkaline solution. The Ag0–Os0 exhibits SPR peaks at 409 nm and 445 nm in absence and presence of NaOH. The composition and morphology of Ag0–Os0 were determined with DLS, EDX, FTIR, SEM, TEM, XRD, XPS, and N2-adsorption desorption techniques. XRD shows the presence of CTAB at the surface of Ag0–Os0. Brunauer-Emmett-Teller (BET) surface area, total pore volume, and average pore size calculated for Ag0–Os0 are 66.23 m2/g, 0.34 cc/g, and 8.10 nm, respectively. The pore size results suggest the formation of microporous of Ag0–Os0. The heterogeneous persulfate activation efficiency of Ag0–Os0 was tested in situ chemical oxidation of safranin. The activated system showed a much higher dye oxidation rate compared to either S2O82− or of Ag0–Os0 alone. The activation energy is found to be 59.14 kJ mol−1 for the in-situ degradation of safranin by Ag0–Os0/S2O82− system. The Ag0 enhanced the persulfate activation due to the synergistic effects of Os0. The reaction mechanism of Ag0–Os0 persulfate activation was proposed and discussed.

One-pot rapid and ultrasensitive sensing strategy for endocrine disruptor bisphenol A using cationic AuNPs and aptamer

A novel Cys-Lys-Arg-Lys-Arg-Lys-Arg peptide-capped cationic gold nanoparticles were synthesized by the utilization of microwave irradiation. The prepared gold nanoparticles along with bisphenol A aptamer have been employed for the development of a colorimetric aptasensor for bisphenol A based on the electrostatic interactions among them and the specific recognizing ability of aptamer. The presence of bisphenol A initiated the formation of bisphenol A-aptamer complex, thus added gold nanoparticles remain stable in the reaction mixture, and corresponding to this very less charge occurs into the surface plasmon resonance peak. Depending on the concentration of bisphenol A, a particular amount of free aptamer was present in the reaction which causes the aggregation of gold nanoparticles, and corresponding to this bisphenol A was detected. Under the optimized conditions, bisphenol A concentrations from 200 to 1000 pM exhibited a good linear correlation (R2 = 0.99581) with a detection limit of 87.04 pM in 7 min. The aptameric ability was studied by replacing the bisphenol A with its other analogues such as bisphenol B, bisphenol F, phenol, and benzophenone, and also in the mixture of all these. The obtained results have shown that the developed aptasensor exhibited five-fold selectivity towards bisphenol A as compared to its other analogues. Utilization of the proposed aptasensor was carried out in mineral water, tap water, and packed juice where the percentage recovery was found from 96.61 to 101.23. Thus, the developed colorimetric aptasensor exhibits excellent advantages of rapidity, simplicity, cost-effectiveness, high selectivity, and sensitivity for bisphenol A.

Fabrication and characterization of Hypecoum pendulum‐assisted novel bio‐inspired silver nanoparticles and their antioxidant, anti‐diabetic, and anti‐Alzheimer properties

This research aims to study the biogenic synthesis and characterization of Hypecoum pendulum extract‐induced silver nanoparticles (HP‐AgNPs) and to investigate its antioxidant, anti‐alpha‐amylase, and anti‐acetylcholinesterase (AChE) activities. UV spectrometry at 417 nm with an surface plasmon resonance (SPR) peak of 1.54 confirmed the biosynthesis of HP‐AgNPs. X‐ray diffraction (XRD) analysis demonstrated that HP‐AgNPs are crystalline with a 36 nm size. The average size of 80 nm was confirmed by scanning electron microscopy (SEM) analysis. The functional moieties bearing compounds accountable for the encapsulation and stability of HP‐AgNPs were assessed by the Fourier transform infrared (FTIR) technique. Energy dispersive X‐ray (EDX) demonstrated that silver was the main element (49%) of HP‐AgNPs. HP‐AgNPs showed the promising antioxidant potential of ABTS (71.57%), diphenyl‐1‐picrylhydrazyl (DPPH, 69.46%), H2O2 (66.94%), ferric chloride (73.71%), and ammonium molybdenum (65.7%). HP‐AgNPs exhibited significant enzymatic inhibition potential with IC50 of 48.8 ± 4.03 μg/mL (α‐amylase) and 51.78 ± 3.16 μg/mL (AChE). Kinetics studies showed that HP‐AgNPs produced mixed‐type inhibition against α‐amylase (Km increased from 40.65 to 131.44%, whereas Vmax decreased from 4.14 to 9.77%) and non‐competitive‐type inhibition (Vmax decreased from 17.05 to 62.03% and Km remain constant) against AChE. Finally, it may be concluded that HP‐AgNPs may possess anti‐Alzheimer, anti‐diabetic, and antioxidant capabilities.

Plant-extract-assisted green synthesis of silver nanoparticles using Macaranga Indica bark extract for antimicrobial and photocatalytic activity

A rapid and environment-friendly green synthesis of silver nanoparticles (AgNPs) using Macaranga Indica (M. Indica) plant extracts was explored in this study. The obtained AgNPs were characterized by UV–Vis, XRD, FTIR, and SEM for antimicrobial and photocatalytic activities. The typical surface plasmon resonance peak around 440 nm confirmed the formation of AgNPs. The particles were found to be very tiny in the range of 15–20 nm size and showed fcc crystal symmetry. The FT-IR study showed the presence of bio-molecules on the surface of AgNPs and acting as capping agents. The in vitro antibacterial screen of AgNPs showed the bio-capped AgNPs have a higher inhibitory action for E. coli and S. aureus followed by C.albicans. The degradation property of the AgNPs towards Rhodamine B (RhB)under different conditions revealed that the degradation efficiency of phytochemicals-coatedAgNPs on RhB was found to be high and around 88.8% within 70 min

Selenite bioreduction with concomitant green synthesis of selenium nanoparticles by a selenite resistant EPS and siderophore producing terrestrial bacterium.

Environmental bacterial isolates play a very important role in bioremediation of metals and toxic metalloids. A bacterial strain with high selenite (SeO32-) tolerance and reducing capability was isolated from electronic waste dump site in Banaras Hindu University, Varanasi, India. Based on 16S rRNA sequencing and BLAST search, this bacterial isolate was identified as Bacillus paramycoides and designated as strain MF-14. It tolerated Sodium selenite up to 110 mM when grown aerobically in LB broth and reduced selenite into elemental selenium (Se0) significantly within 24h with concomitant biosynthesis of selenium nanoparticles as clearly revealed by brick red precipitate and specific surface plasmon resonance peak at 210nm using UV-Visible spectrophotometer. Scanning electron microscopy (SEM) analysis of this bacterial strain exposed to 1mM and 5 mM selenite also demonstrated morphological alterations as cell enlargement due to accumulation and bioprecipitation of elemental selenium (Se0). The FTIR analysis clearly demonstrated that functional groups present on the surface of biogenic selenium nanoparticles (SeNPs) play a significant role in the stabilization and capping of SeNPs. Furthermore, these SeNPs were characterized using spectroscopic analysis involving Dynamic light scattering, zeta potential, XPS, FTIR, XRD and Raman spectroscopy which clearly revealed particle size 10-700nm, amorphous nature, stability as well as it's oxidation state. The biochemical studies have demonstrated that membrane bound reductase enzyme may be responsible for significant reduction of selenite into elemental selenium. Therefore, we may employ Bacillus paramycoides strain MF-14 successfully for bioremediation of selenite contaminated environmental sites with concomitant green synthesis of SeNPs.

Light Induced Synthesis of Ag Nanorods for Potential Application as Optical Filter Tailored to Visible Domain

Monodispersed Ag nanorods were synthesized using a one-pot synthesis method. These Ag nanorods normally manifest dual surface plasmon resonance (SPR) peaks. This work presents a study of the variation of SPR peaks with variation in the shape of Ag nanorods. Shape variation was achieved through the degradation of a shape-controlling agent (PVP in this work) under white light irradiance with silica passivation to halt further shape variations. This paper also reports the growth &amp; characterization of thin films of the synthesized rod-shaped silver nanoparticles on glass slides along with studies on band pass filter characteristics of the as-synthesized nanoparticles.

Synergistic Action of Biosynthesized Silver Nanoparticles and Culture Supernatant of Bacillus amyloliquefacience against the Soft Rot Pathogen Dickeya dadantii.

Nanomaterials are increasingly being used for crop growth, especially as a new paradigm for plant disease management. Among the other nanomaterials, silver nanoparticles (AgNPs) draw a great deal of attention because of their unique features and multiple usages. Rapid expansion in nanotechnology and utilization of AgNPs in a large range of areas resulted in the substantial release of these nanoparticles into the soil and water environment, causing concern for the safety of ecosystems and phytosanitary. In an attempt to find an effective control measure for sweet potato soft rot disease, the pathogen Dickeya dadantii was exposed to AgNPs, the cell-free culture supernatant (CFCS) of Bacillus amyloliquefaciens alone, and both in combination. AgNPs were synthesized using CFCS of Bacillus amyloliquefaciens strain A3. The green synthesized AgNPs exhibited a characteristic surface plasmon resonance peak at 410-420 nm. Electron microscopy and X-ray diffraction spectroscopy determined the nanocrystalline nature and 20-100 nm diameters of AgNPs. Release of metal Ag+ ion from biosynthesized AgNPs increases with time. AgNPs and CFCS of B. amyloliquefaciens alone exhibited antibacterial activity against the growth, biofilm formation, swimming motility, and virulence of strain A3. The antibacterial activities elevated with the elevation in AgNPs and CFCS concentration. Similar antibacterial activities against D. dadantii were obtained with AgNPs at 50 µg·mL-1, 50% CFCS alone, and the combination of AgNPs at 12 µg·mL-1 and 12% CFCS of B. amyloliquefaciens. In planta experiments indicated that all the treatments reduced D. dadantii infection and increased plant growth. These findings suggest that AgNPs along with CFCS of B. amyloliquefaciens can be applied to minimize this bacterial disease by controlling pathogen-contaminated sweet potato tuber with minimum Ag nano-pollutant in the environment.

Green synthesis of silver nanoparticles using paper wasp‘s hydrolysate with antibacterial activity

The last two decades revealed tremendous interest in nanoparticles synthesized via green synthesis and its wide spectra application first of all as effective antimicrobial agents. This research aims to conduct a green synthesis of silver nanoparticles (AgNPs) stabilized by amino acids and oligoproteins. Various conditions (conventional heat treatment, microwave irradiation, and UV-light irradiation pH and concentration of reagents) on yield and size of AgNPs during the synthesis were tested. Alkaline hydrolysate of paper wasp‘s nest was characterized using amino acid analysis, zeta potential, and SDS gel electrophoresis. The protein hydrolysate molecular weight distribution for AgNPs synthesis was predominantly in the range of 0.5 to 10 kDa. The kinetics of the particle synthesis was monitored via intensity change of the AgNPs’ Surface Plasmon resonance UV–V is spectroscopy. The increase of the ionic strength of the AgNP suspension by the addition of salts NaCl and KBr led to aggregation of AgNPs. Zeta potential and hydrodynamic particle size distribution of AgNPs were −46 ± 25 mV and 137 ± 73 nm, respectively. Surface Plasmon resonance peak indicates the dominance of particle size in the range 50–70 nm due to the pH, which influenced on antimicrobial activity. MIC of 7.5 μM AgNPs in combination with 50 μM of benzalkonium chloride against the E. coli strain was (6.9xE8 particles/L) and 25 μM of benzalkonium chloride, while MIC of 73 μM of AgNPs (3.45xE8 particles/L) against Staphylococcus aureus was detected. The antimicrobial effect of the AgNPs suspension irradiated by light spectra at 425 and 630 nm were studied. AgNPs obtained using microwave radiation at a neutral medium were stable for at least 3 months at 4 °C.

Electrophoretic Deposition of Hybrid Calcium Alginate-Gold Nanoparticle Hydrogel Films via Catalyzed Electrooxidation of Hydroquinone

The electrophoretic deposition (EPD) of hybrid alginate (Alg)-Au nanoparticle (NP) films results from the localized pH drop at the electrode surface due to oxidation of hydroquinone (HQ) catalyzed by 4 and 15 nm diameter citrate-coated gold NPs (cit-Au NPs). The localized pH drop at the electrode leads to neutralization of both Alg and cit, leading to EPD of both Alg and cit-Au NPs simultaneously. Post-treatment of the film with Ca2+ solution leads to hybrid Ca-Alg-Au NP hydrogel films. The EPD of Alg in the presence of 4 nm cit-Au NPs occurs at ∼0.8 V (vs Ag/AgCl) as compared to ∼1.0 V in the presence of 15 nm cit-Au NPs and ∼1.4 V in the absence of cit-Au NPs. This is due to the higher catalytic activity of 4 nm cit-Au NPs compared to 15 nm cit-Au NPs for the oxidation of HQ. UV-vis spectra of Ca-Alg-Au NP hydrogel films show absorbance features for both Ca-Alg and Au NPs entrapped within the hydrogel. As the concentration of Au NPs in the EPD solution increases, the Ca-Alg absorbance and localized surface plasmon resonance (LSPR) peak of the Au NPs increases, confirming the role of the Au NPs as a catalyst for EPD of Alg. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of the Ca-Alg-Au NP hydrogel films show characteristic peaks for Ca-Alg and protonated alginic acid groups. The hydrogel thickness is greater with cit-Au NPs compared to without cit-Au NPs at constant EPD potential and time. Forming Ca-Alg and hybrid Ca-Alg-Au NP hydrogel films at low potentials has potential applications in electrochemical and optical sensor development, catalysis, and biological studies.

Cytotoxicity and Antimicrobial efficiency of gold (Au) nanoparticles formulated by green approach using Andrographis paniculata leaf extract

Gold (Au) nanoparticles have flourished a promise for solicitations in biology due to their processability and high performance in the release of therapeutics. The use of leaf substances in the fundamental biosynthesis and manufacturing of nano-phytomedicine is the cooperative effort between plant science and nanotechnology, yielding a green nanostructured material. This study aims to synthesize AuNPs using the extract taken from Andrographis paniculata leaves and to evaluate its efficacy against MCF7 cells and chosen human pathogens. AP-AuNPs were studied with UV, FTIR, and X-ray diffraction spectroscopy, SEM and TEM (scanning and transmission electron microscopy). At 533 nm, a peak of Surface Plasmon Resonance (SPR) was identified using UV–Visible spectra of AuNPs. The XRD diffraction peaks indicated the crystalline nature of gold nanoparticles. The spherical shape was demonstrated by transmission electron microscopy, and dynamic light scattering using Particle Size Analyzer measurements revealed a mean particle size of 40 ± 18.6 nm. The research concluded that using gold nanoparticles derived from herbs is contingent on safe dosage and precise formulation, as stated in ancient literature. MCF7 human breast cancer cells have been used to evaluate the anti-proliferative activity of AuNP. The findings of an oncology investigation revealed that treating cancerous cells using AuNPs drastically diminished the viability of cells. The anti-microbial properties in the primordial herbal-based metal nanoparticles confess the conventional healthcare practice as a progressive approach for contemporary conditions. Based on the investigation, the study inferred that AP-AuNPs are therapeutic in combating human pathogens.

Biogenic synthesis, characterization, and evaluation of synthesized nanoparticles against the pathogenic fungus Alternaria solani.

In the present study, Trichoderma harzianum culture filtrate (CF) was used as a reducing and capping agent to synthesize silver nanoparticles (Ag NPs) in a quick, simple, cost-effective, and eco-friendly manner. The effects of different ratios (silver nitrate (AgNO3): CF), pH, and incubation time on the synthesis of Ag NPs were also examined. Ultraviolet-visible (UV-Vis) spectra of the synthesized Ag NPs showed a distinct surface plasmon resonance (SPR) peak at 420 nm. Spherical and monodisperse NPs were observed using scanning electron microscopy (SEM). Elemental silver (Ag) was identified in the Ag area peak indicated by energy dispersive x-ray (EDX) spectroscopy. The crystallinity of Ag NPs was confirmed by x-ray diffraction (XRD), and Fourier transform infrared (FTIR) was used to examine the functional groups present in the CF. Dynamic light scattering (DLS) revealed an average size (43.68 nm), which was reported to be stable for 4 months. Atomic force microscopy (AFM) was used to confirm surface morphology. We also investigated the in vitro antifungal efficacy of biosynthesized Ag NPs against Alternaria solani, which demonstrated a significant inhibitory effect on mycelial growth and spore germination. Additionally, microscopic investigation revealed that Ag NP-treated mycelia exhibited defects and collapsed. Apart from this investigation, Ag NPs were also tested in an epiphytic environment against A. solani. Ag NPs were found to be capable of managing early blight disease based on field trial findings. The maximum percentage of early blight disease inhibition by NPs was observed at 40 parts per million (ppm) (60.27%), followed by 20 ppm (58.68%), whereas in the case of the fungicide mancozeb (1,000 ppm), the inhibition was recorded at 61.54%.

Preparation and photothermal effect of Chitosan-Alginate-Molybdenum diselenide nanocomposite scaffolds for cancer therapy

Transition metal dichalcogenides (TMDs) have gained significant attention for biological and biomedical applications due to their biocompatible properties and photothermal effects. In the current study, TMD nanosheets were fabricated with poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PPP) triblock copolymer using the liquid exfoliation method. This study prepared TMD nanosheets of PPP-molybdenum sulfide (PPP-MoS2), PPP-tungsten disulfide (PPP-WS2), PPP-molybdenum diselenide (PPP-MoSe2), and PPP-tungsten diselenide (PPP-WS2). The synthesized PPP-TMD nanosheets were characterized using DLS, FT-IR, XRD, SEM, TEM, XPS, and photothermal studies. The DLS results indicated that the nanosheets were 165.1 ± 2.2 to 217.7 ± 2.8 nm and had a zeta potential of −40.9 ± 0.6 to −43.3 ± 0.4 mV and a polydispersity index (PDI) of 0.2. The FT-IR results showed that the fabricated nanosheets contained polymeric substances, and the UV results confirmed that each PPP-TMD had surface plasmon resonance peaks. The XRD patterns of the nanosheets were consistent with those of the International Centre for Diffraction Data. The SEM and TEM results determined that the PPD-TMD sheets were 150 ± 20 nm wide and were single-layer nanosheets with selective area diffraction patterns. The photothermal effects of the PPP-MoSe2 nanosheets at a 30 µg/mL concentration were evaluated at 808 nm with a 1 W cm−2 current. PPP-MoSe2 exhibited the strongest photothermal effect at > 55 °C for 5 min of laser exposure. In addition, the cytotoxicity effects of PPP-MoSe2 were measured with breast cancer cells (MDA-MB-231) with a 5 min laser treatment. At a 30 µg/mL concentration, PPP-MoSe2 inhibited cancer cells by up to 95 %. Further, alginate-chitosan-PPP-MoSe2 composites were developed and evaluated for their photothermal effect. We believe that PPP-MoSe2 will be an excellent material in cancer therapy.

Biosynthesis of silver nanoparticles using extract of banana peel waste assisted by microwave irradiation

Silver (Ag) nanoparticles are among the most desirable nanomaterials for a variety of applications, such as lithium-ion battery, water pollution monitoring, photocatalytic water splitting, and medical devices. Their increased production and integration in environmental applications play an important role for nanoscience and nanotechnology in engineering. The synthesis methods of Ag nanoparticles include physical, chemical, and biological routes. In this study, we reported a rapid, eco-friendly, and cost-efficient method to synthesize Ag nanoparticles using an extract of banana peel waste as a reducing and capping agent under microwave radiation. A comparison between the conventional heating method and microwave radiation revealed that the microwave radiation method for the extraction of banana peel waste and the synthesis of Ag nanoparticles required much shorter extraction and reaction times. The effects of extraction conditions (banana peel content and extraction time) and synthesis conditions (silver nitrate concentration and reaction time) on Ag nanoparticles were investigated. The optimum conditions were found to be for the extraction: 50 g/L banana peel-to-water ratio and microwave extraction time of 140 s at 800 W and for the Ag nanoparticles synthesis: microwave reaction time of 120 s at 800 W and 1 mM silver nitrate solution and. Plasmonic Ag nanoparticles with a surface plasmon resonance peak at 420 nm and an average size of about 149 nm were synthesized.

Biogenic Synthesis of Silver Nanoparticles using Lasiosiphon eriocephalus (Decne): In vitro Assessment of their Antioxidant, Antimicrobial and Cytotoxic Activities.

The emergence of novel nanobiomedicine has transformed the management of various infectious as well as non-infectious diseases.Lasiosiphon eriocephalus, a medicinal plant, revealed the presence of active secondary metabolites and biological potentials. The present study was aimed to demonstrate the biosynthesis of silver nanoparticles using L. eriocephalus leaf extract (LE-AgNPs) and their biological properties, such as antioxidant, antibacterial and anticancer potential. The biosynthesized LE-AgNPs were characterized by UV-Visible spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR) analysis. The antibacterial activity was checked by minimum inhibitory concentration (MIC) and zone of inhibition assays against Gram-positive and Gram-negative bacteria. The anticancer potential of biogenic LE-AgNPs was checked by cytotoxicity and genotoxicity assay against human cervical adenocarcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cells. UV-visible spectroscopy confirmed the formation of silver nanoparticles by measuring the surface plasmon resonance peak of the colloidal solution at 410-440 nm. The results of SEM and TEM revealed the distribution and spherical shape of 20-50 nm sized AgNPs. XRD spectrum confirmed the characteristic peaks at the lattice planes 110, 111, 200, 220 and 311 of silver which confirmed the crystalline nature of biosynthesized LE-AgNPs. FTIR spectrum of plant extract and biogenic LE-AgNPs was recorded in between 1635-3320 cm-1 which confirmed stretching vibrations of possible functional groups C=C and O-H, responsible for the reduction of silver ions to silver nanoparticles. The in vitro antioxidant potential of LE-AgNPs was evaluated using DPPH (IC50 = 26.51 ± 1.15 μg/mL) and ABTS radical assays (IC50 =74.33 ± 2.47 μg/mL). The potential antibacterial effects of LE-AgNPs confirmed that 92.38 ± 2.70% growth inhibition occurred in E. coli in response to 0.1mg/mL concentration of LE-AgNPs followed by P. aeruginosa (75.51 ± 0.76), S. aureus (74.53 ± 1.26) and K. pneumoniae (67.4 ± 3.49). The cytotoxicity results interpreted that the biogenic silver nanoparticles exhibited strong dose and time dependent cytotoxicity effect against selected cancer cell lines where IC50 concentration of LE-AgNPs required to inhibit the growth of HeLa cells after 24 h exposure was 4.14 μg/mL and MCF7 cells 3.00 μg/mL, respectively. Significant DNA fragmentation was seen in the DNA extracted from HeLa and MCF-7 cells exposed to more than 2.5 to 10 μg/mL concentrations of LE-AgNPs. The overall findings from the present investigation indicated that the AgNPs synthesized using L. eriocephalus exerted strong biological potentials such as antioxidant, antimicrobial and extensive cytotoxicity and genotoxicity activities.

A smartphone-based colorimetric assay using Au@Ag core–shell nanoparticles as the nanoprobes for visual tracing of fluvoxamine in biofluids as a common suicide drug

In the present study, bimetallic nanoparticles (NPs) consisting of gold (AuNPs) as the core and silver (AgNPs) as the shell have been synthesized and applied as the nanoprobe for detection of fluvoxamine (FXM) as the anti-depression drug. The physicochemical properties of the prepared citrate-capped Au@Ag core–shell NPs have been characterized by UV–Vis, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. The design of the smartphone-based colorimetric FXM sensor relies on the fast hydrolysis of FXM under alkaline conditions by producing of 2-(Aminooxy)ethanamine without any significant peak at 400–700 nm. The interaction of the resulted molecule with the nanoprobe induced a red shift in the longitudinal localized surface plasmon resonance (LSPR) peak of the nanoprobe, which was accompanied by sharp and vivid color variations in the solution. A linear relationship between the absorption signal increasing by FXM concentration increasing from 1 µM to 10 µM presented a simple, low cost and minimally instrumented format for FXM quantification with a limit of detection (LOD) of 100 nM. The collected visual data with the elegant colorimetric response of the nanoprobe in the presence of FXM from Indian red to light red violet and bluish-purple color offered simple detection of FXM with the naked eye. The satisfactory results of the proposed cost-effective sensor in the rapid assay of FXM in human serum, urine, saliva and pharmaceutical samples guarantee the potential of the nanoprobe for on-site and visual determination of FXM in actual samples. The proposed sensor as the first non-invasive FXM sensor for saliva sample analysis may hold great promise to provide the technical support for the rapid and valid detection of FXM for forensic medicine and clinical organizations.