External reflectance (ER)-FTIR spectroscopy is a non-contact analytical technique particularly suitable for the study of cultural heritage materials having delicate surfaces, such as photographs. Challenges to implementing ER-FTIR spectroscopy in the field of photograph conservation are difficulty in interpreting spectra and a lack of published reference spectra. To investigate the applicability of the technique to characterize diverse types of photographs, archetypes of major photographic print processes common in the 19th and early 20th century were analyzed. The effects of image density, surface gloss, and layer structure were evaluated. Spectra acquired from plain salted paper and albumen prints do not change substantially with image density; cyanotypes show the presence of infrared-active pigment image material, Prussian blue. Beyond identifying materials, such as cellulose and protein, present at the surface of photographs, ER-FTIR spectroscopy can be sensitive to components deeper within the print's structure. For glossy prints on baryta paper, such as gelatin and collodion printed-out prints, interference is generated between the specular surface reflection and the reflection from the binder-baryta interface. Interference patterns in the FTIR spectra are modulated by the presence of silver image material, as shown in spectra from developed-out silver gelatin prints in which information from the baryta layer is completely blocked in the darkest areas of the image. This preliminary study shows that it is possible to classify the photographic process used to make a print and obtain information related to layer structure from multilayered photographs using ER-FTIR spectroscopy. Further work to develop understanding of the multiple effects of complex systems will reveal greater insight into photographic structures and assist in the care and appreciation of prints. & COPY; 2023 Published by Elsevier Masson SAS on behalf of Consiglio Nazionale delle Ricerche (CNR).

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A wealth of period literature from as early as 1856 through the 1920s promoted the toning of salted paper prints with platinum to achieve certain aesthetic effects and improve silver image permanence. A variety of toning bath compositions were proposed to achieve a range of image tones. Additionally, other platinum and matte silver photographic processes, such as kallitypes, silver-platinum prints (e.g., "Satista"), and silver-intensified platinum prints, were popular during the salted paper print revival and may have similar characteristics. However, few examples of prints containing both silver and platinum have been identified in museum collections. To investigate their chemical natures and range of appearances, the authors fabricated prints according to historic recipes. These simulacra were analyzed by XRF spectroscopy and color measurement and artificially aged to provide data relating to metal content, appearance, and longevity. High-resolution electron microscopy of the salted paper print samples revealed the chemical influence of the toning method on the metallic nanostructures that comprise the image. Ultimately, the analytical results are tied to visual observations to elucidate toning methods used by early photographers, contribute to process identification, and draw conclusions about the conservation of these materials.

The photographic work of Captain Linnaeus Tripe (ca. 1851?1860) falls in a transitional decade in which the albumen print began to supplant the salted paper print process. In the 1850s, a wide variety of albumen recipes led to a broad range of print sheens from matte to semi-glossy. These low sheen prints are more difficult to distinguish from salted paper prints. The presence of an albumen binder layer in these prints may not be as obvious as in later albumen prints, even under magnification. Instrumental analysis, such as infrared spectroscopy, can identify the presence of protein but cannot reliably differentiate between a binder layer and a subsequent coating. This paper discusses the visual and scientific analysis of prints created by Tripe. In addition, a set of standardized albumen print simulacra based on a recipe used by Tripe was prepared for comparison to his prints. Both groups of prints were investigated by visual examination, gloss measurement, and non-sampling instrumental analysis by ATR-FTIR, in addition to SEM analysis of the simulacra. The results of the research help to explain the material character of these prints and similar lightly albumenized prints of this period.

From the earliest experiments in silver-based photography, methods have been investigated to increase the permanence and manipulate the tones of silver images. In 1856, Ernest de Caranza published the first example of a platinum-containing toning bath for salted paper prints. However, platinum toning did not gain popularity until the introduction of William Willis’s Platinotype process and the availability of more effective chemicals in the 1870s. Many amateur and professional photographers, including Alfred Stieglitz, published their own platinum toner recipes and tips in specialty journals as this exploratory phase continued, culminating in a widely cited treatise by Lyonel Clark first published in 1890. In subsequent decades, a great variety of toning bath compositions were proposed, which used different concentrations of platinum and other additives to achieve the desired tonal range. Despite the wealth of period literature promoting the process, relatively few examples of platinum-toned silver prints have been identified in museum collections. The present research project aims to recreate historic recipes from published sources, focusing on the salted paper print. Subsequent analyses of simulacra will yield a better understanding of platinum’s use as a toning element in early photographs. A brief overview of documentary evidence relating to toning will be presented along with the preliminary results of the analytical investigation. Ultimately, analytical results will be tied to visual observations of prints, with the goal of contributing to process identification in the field and aiding in the elucidation of toning processes used by early photographers.

The predictable and controllable interaction of small organic or peptidic molecules with biological substrates is the primary reason most pharmaceuticals are narrowly decorated carbon frameworks. The inhibition or activation binding models are measurable and without side reactions that can cause pathological angst. Yet many diseases, especially those involving rapid proliferation of cells (i.e., cancer) or aggregation of peptides (e.g., heart disease, Alzheimer's disease) have not yet been cured by inhibition therapeutics. Additionally, interventional medicine is often required to alleviate such maladies by physical removal first, followed by molecular-level therapy as a second stage. Thus, there appears to be a niche for more aggressive therapeutics that may employ harsher chemical processes to realize clinical efficacy, albeit without causing catastrophic side effects. Molecules that may be considered for this challenge are not typically biomimetic, nor do they fit the traditional pharmaceutical paradigm. They may have unusual modes of action or undesired reactivity that can be lethal if not controlled. These are the outliers; potential pharmacophores that biology does not know how to manage or adapt to. This is why they may be an intriguing class of agents that needs continuous development. In this Account, we connect the under-developed enediyne family of compounds and our metalloenediyne derivatives to existing radical-based therapeutics such as bleomycin and doxorubicin to illustrate that controlled diradical reactivity, although an outlier mechanism, has a place in the therapeutic portfolio. This is self-evident in that of the 11 natural product enediynes known, 2 have clinical impact, a strong ratio. We expand on the chemical diversity of potential enediyne constructs and focus on the accessible trigger mechanisms to activate diradical formation as a method to control toxicity. Moreover, we further illustrate how electromagnetic fields can be employed to activate both molecular and larger nanomaterial constructs that carry highly concentrated payloads of reactive reagent. Finally, we describe how controlled diradical reactivity can reach beyond traditional therapeutic targets such as DNA, to peptide aggregates found in blood clots, neural fibrils, and membrane scaffolds. It is our belief that cleverly constructed frameworks with well-designed and controlled activation/reaction schemes can lead to novel therapeutics that can challenge evolving viral and bacterial invaders. From this evangelical perspective, our hope is that the conceptual framework, if not the specific designs in this Account, stimulate the readership to develop out-of-the-box therapeutic designs that may combat resistant disease targets.

Developing facile synthetic routes to multifunctional nanoparticles combining the magnetic properties of iron oxides with the optical and catalytic utility of noble metal particles remains an important goal in realizing the potential of hybrid nanomaterials.

Halting cancer progression by altering the tumor microenvironment is an exciting new frontier in oncology. One target for new therapies is the structural support provided by the extracellular matrix, which for cancer cells is often abnormal and undergoes drastic modification during angiogenesis, tumor proliferation, and metastasis. We have developed a new magnetic nanoparticle-based agent, Fe3O4-PEG-EDDA (EDDA: (Z)-octa-4-en-2,6-diyne-1,8-diamine), that is capable of generating radicals via Bergman cyclization of the pendant enediyne during mild lryperthermia treatment using an alternating magnetic field. We observe formation of a cyclized aromatic product in the Raman spectra of the thermally excited material and can detect polymeric product after periods of induction. When mixed with the basement membrane extract Matrigel, the nanoparticles do not interfere with normal biopolymer network formation. Applying the same hyperthermia conditions as in solution samples, Fe3O4-PEG-EDDA causes structural collapse of the matrix, visible by electron microscopy, in contrast to the nonradical-forming thermal control Fe3O4-PEG-BD (BD: o-xylylenediamine). Localized damage to the extracellular matrix by nanoparticle-induced molecular transformations represent a conceptual new tool in tumor microenvironrnent modification.

Thrombosis is a hallmark of several chronic diseases leading to potentially fatal heart attacks and strokes. Frontline interventions include intravenous delivery of potent, enzymatic fibrinolytics that possess a high risk for inducing systemic bleeding. As a conceptual countermeasure, we have developed a water-soluble PEGylated gold nanoparticle appended with the enediyne diamine (Z)-octa-4-en-2,6-diyne-1,8-diamine that is capable of photothermally generating 1,4-diradical species under visible excitation (lambda = 514 nm, 100 mW, 26 h). In the absence of biopolymer substrate, photothermal excitation of these particles leads to self-quenching polymer coating formation in water. When these radical-generating nanoparticles are intrinsically applied toward the blood clot structural protein assembly fibrin, as well as its nonpolymerized precursor protein fibrinogen, scanning electron microscopy images reveal significantly modified fibrin clot morphology, as evidenced by larger void spaces and collapsed fiber regions. Quantitatively, laser confocal microscopy images of Alexa Fluor 488-labeled fibrin clots extrinsically treated with nanoparticles at the clot/solution interface show that photothermal radical formation by these particles leads to marked increase in the number of larger pore sizes (>2.0 mu m) within the fibrin matrix, which derive from a corresponding decrease in the histogram of smaller pore sizes (1.52.0 mu m). These larger pore sizes ultimately result in total perfusion of solution through the entire clot volume. The chemical manifestation of this is that radical-induced modifications occur mainly at the protein level but lead to morphological changes at the micron scale. Overall, this technology could have significant impact for disease states such as deep vein thrombosis via a localized, catheter-delivered approach.

Gold nanoparticle theranostic agents have dramatic potential in the fight against disease, particularly cancer, as multifunctional platforms combining biocompatibility, unique optical properties for detection/activation, and heat generation. In this vein, a new thiol-functionalized enediyne surfactant ligand was synthesized and coordinated to gold nanoparticles, as confirmed by the red-shift in the optical spectrum from A. = 520 to 529 nm upon ligand exchange. Raman spectra of the nanoparticle conjugate material show characteristic vibrations at 2192 (alkyne), 1582 (alkene), and 670 cm(-1) (C-S). The photoreactivity of the material is explored under two sets of photolysis conditions: solution, lambda(exc) = 514 nm, RT, t = 8 h; solid aggregate, lambda(exc) = 785 nm, T = -190 degrees C, t = 4 h. Under these conditions, exciting into the surface plasmon of the Au nanopartide substrate transfers heat to the organic ligand layer, initiating enediyne cyclization and generating surface radicals that lead to subsequent polymerization. New vibrational signatures arise in the alkyne (2170-1900 cm(-1)) and aromatic (1520-1200 cm(-1)) spectral regions, indicating the formation of highly conjugated species in the initial stages of the photoreaction. Prolonged irradiation results in the observation of a dense polymer coating in the TEM images, complete loss of observable molecular vibrations in the Raman spectra as a result of strong fluorescence, and a red-shift and broadening of the surface plasmon band in the electronic spectrum. Translation of this approach to nanorods and other architectures is also possible with carbon coatings clearly visible by TEM. The reported nanomaterial design represents a new approach to developing reactive biomedical agents for phototherapy applications, as well as a novel method toward carbonaceous coatings of nanoarchitectures.