Advanced Functional Materials

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Advanced Functional Materials are engineered substances designed to exhibit specific properties and functionalities, such as electrical conductivity, magnetism, or optical characteristics, enabling their application in various high-tech fields, including electronics, energy storage, and biomedical devices. These materials often involve complex structures at the nanoscale and are pivotal in advancing technology and innovation.

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From Bulk to Monolayer MoS2: Evolution of Raman Scattering

by chin yeow Yap

2012, Advanced Functional Materials

Table 1. Summary of the E!, and A,, peak frequencies with various laser lines. “1 L’, “2 L’, “3 L’, and “4 L” indicate monolayer, bilayer, trilayer, anc y 2g gP q y y' y' quadrilayer, respectively. A single data represents the average value from three different samples. The measurement results with 514.5 nm line are extracted from reference [15]. the asymmetric Raman feature centered at 454 cm™ in bulk MoS, is actually a combinational band involving LA(M) and A,, modes. The consistent Ej, and A,, peak frequencies of monolayer MoS, using various laser lines show that Raman spectroscopy is a reliable diagnostic tool to identify monolayer MoS).

Figure 2. Raman characterizations of sample S1 using 488 nm laser line. a) Raman spectra of different locations with various thicknesses on sample S1. The left and right dashed lines indicate the positions of the E}, and A), peaks in bulk MoS), respectively. b) Raman mapping image with the E), peak intensity, c) the E>, peak frequency, and d) the A,, peak frequency. Inset: color bars. The scale bars represent 5 |tm. e) the E}, and A,, peak frequency pro- files along the lines a—b and A-B drawn in (c) and (d). “1 L’, “2 L’, “3 L’, and “4 L” indicate monolayer, bilayer, trilayer, and quadrilayer, respectively.

Figure 3. Raman characterizations of MoS, flakes using various lines. a) Raman spectra of various thicknesses on sample S1 using 325 nm lines. The left and right dashed lines indicate the positions of Exe and A,, peaks in bulk MoS,, respectively. b) Thickness-dependent Es, and A,, peak frequencies using 325, 488, and 532 nm lines, respectively. c) Resonant Raman spectra using 632.8 nm line. d) Peak fitting on the resonant Raman spectra between 360 and 490 cm of bilayer and bulk MoS>. The solid lines are the fitting curves. The spectrum of monolayer MoS, is shown for comparison. “1 L’, “2 L’, “3 L’, and “4 L” indicate monolayer, bilayer, trilayer, and quadrilayer, respectively.

Figure 4. Raman characterizations of sample S2 using 532 nm line. a) The Raman spectra of different locations with various thicknesses on sample S2. Inset: optical image of sample S2. The left and right dashed lines indicate the positions of the E>, and A), peaks in bulk MoS, respec: tively. Raman mapping image with (b) the E), peak frequency and (c) the A,, peak frequency. The scale bars represent 2 um. “1 L’, “2 L’, “3 L’, “4 L’, and “5 L” indicate monolayer, bilayer, trilayer, quadrilayer, and quin- quelayer, respectively.

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Nanomaterials via Laser Ablation/Irradiation in Liquid: A Review

by Shikuan Yang and

2012, Advanced Functional Materials

Figure 5. TEM images and corresponding size histograms of NPs produced by LAL of Ag target in a) 0.003 m, b) 0.01 m, and c) 0.05 m aqueous SDS.|*° Reproduced with permission.!**] Copyright 2011, American Chemical Society.

Figure 9. SEM images of nanostructures produced by a) conventional LAL and b,c) electric-field assisted LAL with b) 14.5 V and c) 32 V dc voltages. Reproduced with permission.!'78] Copyright 2008, American Chemical Society. Liquid circulation above the target surface can remove NPs and cavitation bubbles from the ablation zone. On the other hand, the scanning optics technique can help the laser beam In addition to metal targets, some reactive liquid media can also act as targets to absorb laser beam energy and produce com- pound NPs. As an example, Henley and co-workers took advan- tage of laser heating along with the traditional hydrothermal

Figure 10. Variation in the productivity of NPs with interpulse distance and scan speed employing laser pulse energy of 4.6 mJ per pulse, 4 kHz repetition rate, and 4 mm thickness of the liquid layer. Schemes of ablation, laser pulse, cavitation bubble, and heat-and-shock-wave- affected zone. Reproduced with permission.!"75l Copyright 2010, American Chemical Society.

Figure 16. a) Violet-blue photoluminescence spectra of Zn/ZnO core/shell NPs obtained by LAL with different laser powers. The inset presents the usual UV and green emission of ZnO NPs after high-temperature annealing. b) Normalized visible emission spectra from blue to green regions recorded for ZnO NPs fabricated by LAL and treated under different low-temperature annealing conditions. Reproduced with permission.|*I

Figure 19. Photographs of TiO, treated seed germination A) 3 days, B) 4 days, and C) 5 days of sowing. D) Magnified image of 4 mm (mil) and 5 mu TiO, treated Brassica oleracea var. capitata sees after 5 days of sowing. E] Histogram of percentage of seeds germinated after 1-4 days of sowing for different concentrations of TiO, NPs. Reproduced with permission."”4] Copyright 2012, American Scientific Publishers.

Figure 13. Assemblies of drop-shaped zinc oxide QDs into various dendritic nanostructures and three possible branching schemes. Reproduced witt permission." Copyright 2011, Elsevier.

Figure 2. Schematic illustration of the formation of FeO NPs by LAL. Step |: Production of high-temperature and high-pressure iron plasma above the iron target quickly after one laser pulse. Step II: Ultrasonic and adiabatic expansion of the plasma and formation of iron clusters. Step III: Formatior of ferrous oxide NPs. Reproduced with permission.8] Copyright 2005, American Chemical Society.

Figure 7. a) Photographs of colloid dispersions of Ag: Au alloy NPs of different composi- tions and b) corresponding UV-visible SPR absorption spectra. Reproduced with permission.”4 Copyright 2003, American Chemical Society. The laser irradiation of metal salt solutions or liquid precursors is a bottom-up approach that generates a colloidal dispersion of NPs.!’7-828] Here metal salts are photo-chemically induced to generate neutral M° atoms, which then undergo clustering to form NPs.!’7-8*86] Photochemical synthesis is also a clean, quick, and simple process that provides i) a controlled synthesis of NPs and ii) a synthesis of NPs in various media such as sol, emulsion, glass, surfactant micelles, polymers, etc. Based on the processes involved, the photochemical decomposition of

Figure 4. Schemes for direct photoreduction and photosensitized reduction of metal salt solu- tion or liquid precursors (as metal source). Reproduced with permission."! Copyright 2009, Elsevier.

Scheme 1. Direct photoreduction of AgClO, in aqueous and alcoholic media for the sythesi: of Ag NPs.!”71 Copyright 1976, American Chemical Society.

Figure 1. a) A plasma plume ejected from a laser-irradiated SrRuO; target. b) Schematic setup of pulsed laser deposition (PLD) in a vacuum chamber for thin film growth. c) pulsed laser ablation (PLA) in a tube furnace for nanowire/nanotube growth. d) LAL setup for nanoparticle growth.

Figure 3. Schematic diagrams of metal nanodroplet ejection and nano- structure formation in the LAL process using a low-energy millisecond laser. a) Formation of nanodroplets. b) Reactions of an ejected metal nanodroplet with ambient liquid. c) Effect of liquid reactivity and laser frequency on the morphology of nanostructures formed when a Pb target was ablated in liquids. Reproduced with permission.?4 Copyright 2010, American Chemical Society.

Scheme 2. Photosensitized reduction of the source precursor for the synthesis of metal NPs.!'6l Copyright 2002, Royal Society of Chemistry. Relatively low product yield is one of the main disadvantages associated with LAL. The simplest solution for scaling up

Figure 6. Suspension photographs, as well as the variation in the size and bandgap energy o' the prepared a-Se QDs as they change with irradiation time. Reproduced with permission.|®© Copyright 2010, American Chemical Society.

Figure 11. TEM images of various nanostructures obtained via LAL by ablating Pb in various S-containing liquids and using different laser parameters: a) core/shell NPs with Pb core and PbS shell; b) PbS hollow NPs; c) PbS nanocubes; d-f) high-resolution TEM (HRTEM) images of the nanostructures in (a—c), respectively; g) Pb-PbS heteronanostructures; the inset shows a HRTEM image of a Pb-PbS NP; the scale bar indicates 3 nm; h) a PbS polycrys- talline nanotube; the inset shows a HRTEM image of a NP in the nanotube; scale bar indicates 3 nm; and i) ordered arrays of PbS nanocrystals; the inset is a HRTEM image of such a nanocrystal; scale bar indicates 3 nm. Reproduced with permission.?4 Copyright 2010, American Chemical Society.

5.3. NP Thin Films for SERS Detection Applications Figure 15. Detection of PSMA positive structures in prostate cancer tissuesections by immu: nohistochemical staining using anti-PSMA aptamer (PSMA apt)-conjugated Au NPs. As a nega- tive control, Au NPs conjugated with miniStrep aptamer (miniStrep apt) were used. Apolyclona antibody directed against PSMA (PSMA pAb) was used as a positive control. The positive control was additionally stained with aematoxylin and Eosin. Black arrows indicate specific staining, while white arrows show unspecific binding. Reproduced with permission. !!55] Copy- right 2010, Springer.

Figure 12. Energy dispersive X-ray high-resolution TEM (EDX-HRTEM) chemical mapping images of Ag-Au alloy NPs demonstrating the presence of a) Ag and(b) Au in four NPs marked by yellow arrows and observed in c) as a TEM image. d) Apart from Ag and Au, the EDX-HRTEM also reveals the presence of Si which is mainly concentrated around the NPs. e) A HRTEM image and f) a schematic model of a NP, where a yellow dotted line in (e) indicates the limit of SiO, shell. Reproduced with permission.!'*7] Copyright 2010, American Chemical Society.

Figure 14. Schematic illustration of the in situ bioconjugation process for NPs via laser ablation in liquid. Reproduced with permission.!4I Bioconjugated NPs have attracted increasingly more atten- tion as convenient and important analytical tools for biological and medical applications. If certain surfactants, polymers, or biomolecules are added into the liquid medium, the in situ conjugation onto the NP surfaces can be realized, as shown in Figure 14.!4446161] Tn situ functionalization during the LAL formation of NPs was first envisaged to improve the stability of obtained colloids,!!°3) while currently it aims at the one-step preparation of bioconjugated NPs.'4I

Figure 17. Time evolution of the free base (330 cm™') and the Ag metalloporphyrin (395 cm™') marker bands in the SERS spectra of Ag colloid, H,TMPyP system: a) ablated, b) borohydride-reduced, and c) citrate-reduced Ag colloids. SERS spectra were measured on the time scale of 40 s t 20 min; bottom spectra were obtained 40 s and top spectrum 20 min after the preparation of the system. Reproduced with permission." Copyrigh 1997, American Chemical Society.

Figure 8. Experimental arrangement for electric-field-assisted pulsed laser ablation in liquid Reproduced with permission.!'28l Copyright 2008, American Chemical Society.

Figure 18. SERS spectra of Rodamine 6G (R6G) molecules adsorbed on Ag nanoshells, which were composed of LAL-formed NPs with dif- ferent sizes. All SERS data are averaged over 5 scans on randomly chosen areas and the standard deviation was less than 10%. Reproduced with permission. |"

Al-Wen Du received nis Pn.D. in Materials Physics and Chemistry from Tsinghua University in 2001, then worked at the Motorola Company and the National Institute for Materials Science (Japan). He was then appointed Associate Professor at Tianjin University in 2003 and promoted to Full Professor in 2007. He leads the research group for quantum-dot materials and devices.

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Inorganic Luminescent Materials: 100 Years of Research and Application

by Cees Ronda

2003, Advanced Functional Materials

. Schemes illustrating the underlying physical processes of luminescence on isolated centers (left, middle) and in semiconductors (right).

Fig. 2. a) Emission spectrum of Cas(PO,)3(CI,F):Sb**,Mn** (solid line) as used in single-phosphor lamps compared to the eye sensitivity curve. b) Emission spectra of BaMgAlQ,7:Eu’* (solid line), LaPO4:Ce**,Tb** (dotted line), Y,03:Eu** (dashed line) as used in tri-color lamps (in a 10:60:30 mixture) compared to the eye sensitivity curve.

Fig. 3. A coated phosphor: o-Fe2O3 particles on Y20>S:Eu**.

Fig. 4. Diagram of blue-emitting LED-chip with phosphor particles for color conversion.

Fig. 5. Energy transfer and down-conversion in LiGdFy:Eu*.

Table 1. Early milestones in the discovery of luminescent materials and devices.

Table 2. Most important phosphors for practical use.

Fig. 1. Schemes illustrating the underlying physical processes of luminescence on isolated cen- ters (left, middle) and in semiconductors (right).

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Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical Conductance

by Hyeon-jin Shin

2009, Advanced Functional Materials

Figure 1. XRD patterns of GO, graphite (G), and reduced GOs obtained using various molar concentrations of NaBHy,. Figure 1 shows the XRD patterns of films reduced using various molar concentrations of NaBH,. The interlayer distance obtained from the (002) peak was 3.38 A (20 = 26.4°) in graphite. This was markedly expanded to 8.27 A (26=10.7°) with oxidation to form GO (Fig. 1, top pattern).?17) The large interlayer distance has been attributed to the formation of hydroxyl, epoxy, and carboxyl groups. With reduction, the interlayer distance is expected to

Figure 2. The C 1s peak in the XPS spectra of GO (a), reduced GO obtained using 15 (b), 50 (c), and 150mm NaBH, (d), and graphite (f); the curve was fitted considering the following contributions: C=C (sp*; peak 1), C—C (sp; peak 2), C-O/C—O—C (hydroxyl and epoxy groups; peak 3), C=O (carbonyl groups; peak 4), O—C=O (carboxyl groups; peak 5), and 1-1" (peak 6). e) The B 1s peak in the XPS spectrum of the reduced GO obtained using 15 mm NaBH.

Figure 3. a) UV-vis and b) Raman spectra of GO and RGO films and c) the dependence of the D:G ratio on the NaBH, concentration in the RGO films.

Figure 5 shows how sheet resistance varied with respect to the transmittance for different film thicknesses. Our NaBH,-reduced GO films exhibited the lowest sheet resistance compared to all other RGO sheets, which were reduced using NjHy.4°!4 For instance, at a transmittance of 83%, the sheet resistance of our RGO film was 5.2kO, sq (Table 4); this is significantly smaller than 1500MQ sq™! or 100kQ sq~', which were observed for samples that had been additionally thermally annealed at 200 °C under nitrogen (or vacuum) in spite of a 3% reduction of oss eee Gayes TIT Gee tee pee ed oe nner Figure 4. a) Dependence of the conductivity on the C:O ratio and b) the valence band structure of RGO films obtained using various concentrations of NaBHy4. The electronic properties of RGO are closely related to its structural properties. Figure 4a shows the conductivity and C:0 ratio as a function of the molar concentration of NaBH4,. The behavior of the conductivity and C:O ratio were very similar to each other the NaBH, concentration was increased. Conductivity of the film was directly related to the oxygen content. Complete removal of residual oxygen content even when using high NaBH, concentrations was the key factor in further reducing the sheet resistance. The presence of oxygen atoms also affects the

Figure 5. Sheet resistance versus transmittance at 550nm for NaBH,- reduced GO films before (open circles) and after (solid circles) Au-ion doping and NjH,-reduced GO films reported by others (Becirril, Eda, and Li correspond to references 10, 11, and 12, respectively).

Table 1. Sheet resistance and elemental composition of reduced GO films using NaBH, or N2Hy,, as the reducing agents

Table 2. The C 1s peak position and the relative atomic percentage of various functional groups in GO, graphite, and RGO films obtained using different molar concentration of NaBH.

Table 3. Electrical properties of the RGO films obtained using various concentrations of NaBH, and their related work functions.

Table 4. Percent transmittance (%T) at 550nm and sheet resistance (R, [kQ sq ']) of RGO films in this study and other related studies.

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Microscopical Investigations of PEDOT:PSS Thin Films

by Jurg Dual

2009, Advanced Functional Materials

Electron microscopy studies are used to explore the morphology of thin poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate acid (PEDOT:PSS) films. The figures show that the films are composed of grains with diameters in the range... more

Figure 6. HAADF-STEM image. The film seems to be composed of individual spots in the range of about several nanometers. The scalebar represents 10nm.

Figure 3. HAADF-STEM image of a 25-nm-thick PEDOT:PSS film. The individual grains are clearly visible with an average diameter of about 50nm. The grains are surrounded by a thin bright ring. In the lower right corner an agglomerate of larger grains with a diameter of about 200 nm is partly visible. The scalebar represents 100 nm. Atl OFGer lO fevedt tile CiemiCal COMMPOsSIUOL OL the films and to confirm the assumption that the agglomerates are made of PEDOT:PSS an energy dispersive X-ray (EDX) investigation was conducted. Figure 4 shows typical areas of the analysis and Table 1 tendencies for the relative atomic concentrations. From these results several conclusions can be drawn. First of all, the agglomerates and the film are made from the same elements and are therefore very probably the same material and not contaminations from the fabrication process of the film. Then there are large differences in brightness between the film and the agglomerates. Because the elemental concentrations are principally the same for the film and the agglomerates, these differences in brightness must stem from very different thicknesses. We therefore conclude that the agglomerates are on top of the film (see Fig. 4B). The next observation is that the relative sodium and calcium concentra- tions in the contact areas of grains are significantly higher than in the rest of the film. Na and Ca most likely stem from the fabrication process of Clevios P.'°! As Na and Ca are relatively heavy elements, an increase in relative concentrations will lead, under the assumption of same thickness of contact and core

Figure 9. AFM scans of a 25-jm-thick sample ruptured at 23% relative humidity. On the topography image (left) it can be seen that the fracture surface is fairly smooth with some striations that we attribute to brittle fracture propagation. Partially individual grains are visible which can be attributed to some small plastic deformation. From the phase images (right) it can be concluded that there are areas with different sample elasticity. It seems that particles (bright areas) are dispersed in a matrix (dark areas). We attribute the bright spots to areas with high PEDOT content. Dark areas should therefore be a PSS-rich matrix. This would confirm the currently accepted model for PEDOT:PSS morphology. from the substrate could be obtained. Samples ruptured at 23% relative humidity are shown in Figure 9. For the sample tested at 23% relative humidity the scans (Fig. 9) partly show a fairly smooth surface. This is attributed to brittle crack propagation. Nonetheless there are also grains visible which is an indication for some plastic deformation. This is in accordance with the results obtained in Ref. [1] where even for samples with almost brittle behavior some plastic deformation could be observed.

Figure 1. Model of PEDOT:PSS solid thin film formation on a substrate, e.g., glass: A) side views of model for pancake-like morphology of PEDOT:PSS. Individual spherical gel particles are randomly distributed in the dispersion. Upon drying, a wet film is formed first before a solid dry film is obtained. During drying some lateral shrinkage and a considerable decrease in thickness takes place. This decrease in thickness is influenced by the substrate on which the PEDOT:PSS is deposited and caused by adhesive effects. B) It is assumed that hydrogen bonds develop between HSO; groups of the PSS-rich outer shell of individual gel particles and therefore promote adhesion between individual PEDOT:PSS grains (with permission from Ref. [9], copyright 2008 H. C. Starck GmbH).

Figure 7. Part of PSS chain with PEDOT segments building ionic complexes (with permission from Ref. [9], copyright 2008 H. C. Starck GmbH.) The respective molecular weights are also given. Along the whole chain the mass ratio of 1:2.5 for Clevios P has to be fulfilled. as polyanion assume a spheroidal shape when dispersed in pure water. Therefore, the assumptions presented here are based on the idea that in Figure 6 the spots are caused by individual spheroidal spaghetti-like tangles. Each of the tangles is composed of a single PSS chain with adherent PEDOT segments (see Fig. 7 for a model of the structure of a PEDOT:PSS chain with corresponding molecular weights). During synthesis these chains assume a spheroidal shape to shield the hydrophobic PEDOT segments from the aqueous environment. Furthermore, PEDOT crosslinks between nonadjacent PSS segments might additionally support the formation of a globular shape of PEDOT:PSS. The right panel of Figure 8 shows a sketch of this model. Several chains then entangle and form a grain. Upon drying, the spheroidal shape is then preserved for both grains and tangles inside the grains. As the weight ratio of PEDOT:PSS is 1:2.5 in Clevios P, one can then assume that the average molecular weight of that PEDOT:PSS chain is 160000+400000g mol '= 560000g mol‘. In another publication the mass density of

Figure 2. Brightfield TEM picture showing the morphology of a ~25-nm- thick PEDOT:PSS film. Circles have been added to emphasize the visibility of some of the grains. The grain size distribution resembles the one of the aqueous dispersion [2] under the assumption of some lateral shrinkage during drying. reveal their morphology. Figure 2 shows typical results. The granular structure of PEDOT:PSS could be confirmed, with an average grain diameter of about 30-50nm. The distribution of grain diameters in the solid film seems to correspond fairly well to the one in the aqueous dispersion if some lateral shrinkage during drying of the film is assumed. These findings therefore support the pancake morphological model. Furthermore, adverse effects of the organic solvent used to fabricate the films by a floating-off process can therefore also presumably be excluded as the morphology is not fundamentally changed. In the next step, high angle annular dark field (HAADF) scanning TEM (STEM) was used as another analytical method to enhance the contrast of grain boundaries. The HAADF-STEM method is based on the incoherent scattering of an electron beam comparable to Rutherford scattering. In general, the image contrast shows a linear dependence on the sample thickness and a nearly square dependence on the atomic number Z of the respective atomic species present in the sample. Figure 3 shows the clearly visible individual grains. The average grain diameter seems to be around

Figure 8. Hypothesis for the morphology of individual PEDOT:PSS grains. We propose that a grain is composed of numerous tangles. Each tangle is made of a single PSS chain with several PEDOT segments adherent to it. Inside the grain the tangles are shaped in such a way that PEDOT segments are evenly distributed in space. In the outer layer of the grain the tangles arrange themselves in such a way that mostly their hydrophilic PSS parts point toward the outside. The grains can thus be dispersed in an aqueous solution.

Table 1. Results of the EDX analysis: relative atom concentrations in different areas [a]. [a] The numbers of the the EDX-quantification were deduced standardless with the sum of the composition being standardized to 100%. Therefore the absolute values should be regarded as arbitrary units, which only show tendencies. Furthermore the concentrations are averages over the whole area of the boxes and were obtained by several different measurements.

Figure 5. Linescan of signal intensity of the HAADF-STEM analysis (x-coordinate: length in nm, y-coordinate: signal intensity in arbitrary units). The width of the peaks (marked by arrows) is in the range of about 5-10 nm. We attribute these peaks to increased Na and Ca and therefore PSS concentration which therefore also confirms the findings shown in Ref. [4, 5] The bar represents 100 nm.

Figure 4. A) HAADF-STEM image of 25-nm-thick solid PEDOT:PSS film with several agglom- erates exemplarily showing different areas from which the EDX spectra of Table 1 were acquired. Area 1 represents contact areas between individual grains of an agglomerate, area 2 stands for cores of grains of an agglomerate, and area 3 means that the measurement was acquired from the background, i.e., the 25-nm-thick PEDOT:PSS film. B) Schematic showing how agglomerates lie on top of the film.

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New Generation of Multifunctional Nanoparticles for Cancer Imaging and Therapy

by 민직 김

2009, Advanced Functional Materials

Advances in nanotechnology have contributed to the development of novel nanoparticles that enable the tumor-specific delivery of imaging probes and therapeutic agents in cancer imaging and therapy. Nanobiotechnology combines... more

Figure 10. a) Illustration and TEM images of the magnetic gold nanoshell: (Mag-GNS). b) T2-weighted MR images of control SKBR3 cells, HER2/neu negative H520 cells incubated with Mag-GNS-AbyeR2/neu and HER2/neu positive SKBR3cells incubated with Mag-GNS-Abyer2/neu; the correspond ing T2 relaxation times are indicated. c) Optical microscopy images o control SKBR3 and SKBR3 cells incubated with Mag-GNS-Abyer2/neu afte irradiation and subsequent staining. Reproduced from Reference [126].

Compared to the administration 0! small molecules, the nanoparticle delivery systems can deliver a higher amount o: drugs (10- to 100-fold) to the vicinity of the tumors,”! thus improving therapeutic efficacy and reducing harmful non-specific side effects. The use of nanoparticles a: drug-delivery systems for anticancer ther apeutics has great potential to revolutio: nize the future of cancer therapy. In addition, nanoparticles with imaging agents offer opportunities to exploit optical imaging or MRI in cancer imaging, and guided hyperthermia therapy. Therefore we optimistically believe that the integrated systems that combine differing properties targeting, therapy, and imaging in an all-in-one ovide more useful multimodal approaches ir st cancer. As illustrated in Figure 1, by exploiting Figure 1. Multifunctional nanoparticles. Multifunctional nanoparticles can combine a specific targeting agent (usually with an antibody or peptide) with nanoparticles for imaging (such as quantum dots or magnetic nanoparticles), a cell-penetrating agent (e.g., the polyArg peptide TAT), a stimulus-selective element for drug release, a stabilizing polymer to ensure biocompatibility (polyethylene glycol most grequently), and the therapeutic compound. Development of novel strategies for controlled released of drugs will provide nanoparticles with the capability to deliver two or more therapeutic agents. Reproduced with permission from Reference [8]. Copyright 2008, Elsevier Ltd.

Figure 3. a) Schematic diagram of the PM-PDT strategy. Fluorescence and SOG is quenched due to energy transfer between Ce6 molecules. Following proteolytic cleavage of the peptide backbone, released Ce6 and SOG regain their fluorescent properties after light excitation. b)—D) In vivo activation of PM-PDT. B) Distribution of Ceé6 in bilateral flank tumors. c) Images of tumor tissues that were stained after treatment with Ce6-conjugated L-PGC and light. d) TUNEL staining of Ce6-conjugated L-PGC-treated tumors 24h after light illumination. Reproduced with permission from Reference [45]. Copyright 2006, American Association for Cancer Research.

Figure 9. a) Schematic illustration to demonstrate that the cells containing EGFP-GNR conjugates within a spot (3.5 mm in diameter) are irradiated by an NIR laser (left). After laser irradiation, the gold nanorods of EGFP-GNR conjugates undergo shape transformation that results in the release of EGFP DNA (right). b) TEM images of EGFP-GNR conjugates before (left) and after (right) irradiation with a laser beam. c) Expression of EGFP in cells incubated with the DNA-GNR conjugates. Left) The bright-field image of cells (white circles) incubated with the conjugates after laser irradiation. Right) The confocal image of the same cells showing GFP expression. Reproduced with permission from Reference [125]. Copyright 2006, American Chemical Society.

Figure 6. A multifunctional probe for in vivo dual-modality imaging and therapy. a) Schematic illustration of the multifunctional probe consisting of a magnetic nanoparticle labeled with a near-infrared dye Cy5.5, membrane translocation peptides (MPAP), and siRNA molecules targeting green fluorescent protein (siGFP). b) In vivo MRI of mice bearing subcutaneous LS174T human colorectal adenocarcinoma (arrows) before and after treatment. A high-intensity NIRF signal in the tumor confirmed the delivery of the nanoparticle. Reproduced with permission from Reference [95]. Copyright 2007, Nature Publishing Group. Based on the facts that biocompatible polymers are suitable for targeted drug delivery,°?°”°*! Yang et al. have suggested a

Ringsdorf’s vision of the idealized polymer chemistry for drug conjugation produced the concept of targetable polymer—drug conjugates.'"*] The polymer-drug linkers were designed to be stable in the blood, deliver adequate drug amount, and able to release drug at an optimum rate at the target sites. One representative example is N-(2-hydroxypropyl)-methacrylamide

Figure 4. Schematic illustration of Bi-FRET-based quantum-dot—aptamer- doxorubicin conjugate as a targeted cancer imaging, therapy, and sensing system. Reproduced with permission from Reference [56]. Copyright 2007 American Chemical Society.

Figure 7. a) Schematic illustration for the fabrication of MMPNs. b) MR image and color map (tumor region) of the cancer-targeting events of HER- MMPNs. C) Comparative therapeutic-efficacy study in an in vivo model. Reproduced from Reference [99]. A light-activated theragnostic nanosystem has been developed by the Brian Ross group. These MMPNs have a polyacrylamide (PAA) core and contained Photofrin (PDT agent), iron oxide (MRI agent), F3-peptide (tumor vascular homing peptide), and PEG for increase circulation time.!'°°! To determine cellular uptake, the particles were also fluorescently labeled with Alexa Fluor 594. The resulting particles were approximately 40nm in diameter, and

cles (TCL-SPIONs) have been developed by using an anti- biofouling PEG polymer containing Si-OH, poly(3-(trimethox- ysilyl)propyl methacrylate-rPEG methyl ether methacrylate-r-N- acryloxysuccinimide).°7! The COOH of TCL-SPIONs was further converted to amine-modified TCL-SPIONs, and then finally conjugate Cy5.5 to obtain Cy5.5 dye-labeled TCL-SPIONs for use as a multimodal (MR/fluorescence) imaging probe.**! MRI and Figure 5. a) Illustration of DOX@TCL-SPIONSs. b) T2-weighted fast spin— echo images taken at Oh and 4.5h after injection of DOX@TCL-SPION in LLC-tumor bearing mice. c) Optical fluorescence images of major organs and tumor: 1 liver; 2 lung; 3 spleen; 4 tumor; 5 heart; 6 kidney. d) Results of tumor volume inhibition from each treatment group. Reproduced from Reference [84].

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Two-Dimensional Molybdenum Trioxide and Dichalcogenides

by Hussein Nili

2013, Advanced Functional Materials

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Microwave-Assisted Synthesis of Nanocrystalline MgO and Its Use as a Bacteriocide

by Jacek Jasinski

2005, Advanced Functional Materials

Nanocrystalline particles of MgO were synthesized using microwave radiation in an ethylene glycol solution. The antibacterial activities of the MgO nanoparticles were tested by treating Escherichia coli (Gram negative) and Staphylococcus... more