Aleksandra Wajda

We present herein a previously unreported chiroptical phenomenon, leveraging the intrinsic optical nanoscale-originated properties of chiral (l- and d-cysteine derived) carbon dots (C-Dots), specifically, their surface (low-lying electronic excited) states. We show here that these structures generate an exceptional chiroptical response that, furthermore, can be transferred to molecularly chiral entities interacting with C-Dots. In such assemblies, C-Dots behave as nanoantennas, losing their own chiral identity to the advantage of the newly formed chiral (nano)assemblies that show at least 20-times higher intensity of vibrational optical activity compared to the molecular chirality signal. In a conceptual way, the observed phenomenon is similar to surface-enhanced Raman and Raman optical activity (ROA) spectroscopies, in which nanoparticles, in resonance with the incoming light, enhance the electromagnetic field around analyzed molecules, amplifying their Raman or ROA signal. Our findings enable the application of C-Dots as highly efficient chirality nanosensors which, in light of their rich surface chemistry, translates to the broad potential for the development of C-Dots-based nanoprobes with tailored properties as well as for the rational design of next-generation chiral nanomaterials.

We present herein a novel chiroptical phenomenon, leveraging from the unique optical nanoscale-originated properties of chiral (L- and D-cysteine derived) carbon dots (C-Dots), specifically their surface (low-lying electronic excited) states. We show here that these structures generate an exceptional chiroptical response that, furthermore, can be transferred to molecularly chiral entities interacting with C-Dots. In such assemblies C-Dots behave as nanoantennas, losing their own chiral identity to the advantage of the newly formed chiral (nano)assemblies that show at least 20-times higher intensity of vibrational optical activity compared to the molecular chirality signal. In a conceptual way, the observed phenomenon is similar to surface enhanced Raman and Raman optical activity (ROA) spectroscopies, in which nanoparticles, in resonance with the incoming light, enhance the electromagnetic field around analyzed molecules, amplifying their Raman or ROA signal. Our findings open perspectives for the application of C-Dots as highly efficient chirality nanosensors which in light of their rich surface chemistry translates to the broad potential for the development of C-Dots based nanoprobes with tailored properties as well as for rational design of next-generation chiral nanomaterials. In the broader view, the observed phenomenon may be recognized in future as an inherent feature of nanostructures which properties are dictated by effects of quantum confinement combined with surface defects (C-Dots, quantum dots, nanowires, perovskites, etc.), potentially unlocking a range of novel optochiral effects.

This feature article focuses on exceptionally intense ROA of amyloid fibrils, discussed in the broader context of ROA signal enhancement.

Heme released from damaged and senescent red blood cells (RBCs) may contribute to oxidant-mediated cell injury. One of the recently investigated physiological processes, essential in preventing the inflammatory impact of labile heme, is its uptake from the bloodstream by endothelial cells (ECs). In this study, we investigated heme uptake by ECs starting from the model studies on the in vitro cellular level, through the endothelium layer on the ex vivo murine aortic tissues. As the cellular model, Human Aortic Endothelial Cells (HAECs) were chosen, and the concentration of labile heme was adjusted so to avoid the excessive toxic effect of the labile heme. We utilized label-free Raman imaging with two different excitation wavelengths to capture the uptake process in situ and characterize the oxidation state of the iron ion in the intercalated heme. The phenomenon of heme uptake was demonstrated in both, the healthy control C57Bl/6J and FVB animals, as well as in mice with developed atherosclerosis (ApoE/LDLR^−/− mice). In the presented work, we presented for the first time Raman-based evidence on the heme uptake process by endothelial cells in both, in vitro and ex vivo systems.

We report enormous enhancement of ROA signal detected for mature amyloid fibrils and/or prefibrillar states of different proteins. ROA is observed at earlier stages of fibril formation than VCD and provides access to a broader range of vibrations.

Amyloid fibrils are fascinating and complex structures with the multilayered chiral organization. Using the multimodal methodology, including VCD, ECD, cryo‐EM, and TEM, we characterized in detail different levels of organization (secondary structure/protofilament/mesoscopic structure) of amyloid fibrils prepared from proteins highly homologous in the structure (hen egg white and human lysozymes). Our results demonstrate that small changes in the native protein structure or preparation conditions translate into significant differences in the handedness and architecture of the formed fibrils at various levels of their complexity. In particular, fibrils of hen egg white and human lysozymes obtained in vitro at the same preparation conditions, possess different secondary structure, protofilament twist and ultrastructure. Yet, formed fibrils adopted a relatively similar mesoscopic structure, as observed in high‐resolution 3D cryo‐EM, scarcely used up to now for fibrils obtained in vitro in denaturing condition. Our results add to other puzzling experiments implicating the indeterministic nature of fibril formation.

Patients worldwide require therapeutic transfusions of packed red blood cells (pRBCs), which is applied to the high-risk patients who need periodic transfusions due to leukemia, lymphoma, myeloma and other blood diseases or disorders. Contrary to the general hospital population where the transfusions are carried out mainly for healthy trauma patients, in case of high-risk patients the proper quality of pRBCs is crucial. This leads to an increased demand for efficient technology providing information on the pRBCs alterations deteriorating their quality. Here we present the design of an innovative, label-free, noninvasive, rapid Raman spectroscopy-based method for pRBCs quality evaluation, starting with the description of sample measurement and data analysis, through correlation of spectroscopic results with reference techniques' outcomes, and finishing with methodology verification and its application in clinical conditions. We have shown that Raman spectra collected from the pRBCs supernatant mixture with a proper chemometric analysis conducted for a minimum one ratio of integral intensities of the chosen Raman marker bands within the spectrum allow evaluation of the pRBC quality in a rapid, noninvasive, and free-label manner, without unsealing the pRBCs bag. Subsequently, spectroscopic data were compared with predefined reference values, either from pRBCs expiration or those defining the pRBCs quality, allowing to assess their utility for transfusion to patients with acute myeloid leukemia (AML) and lymphoblastic leukemia (ALL).

The aggregation-sensitive chiroptical (ECD and RROA) output, provided by enantiopure (3S,3′S)-astaxanthin, was used to investigate and control the assembling processes of the carotenoid in Pluronic F-127 nanoparticles. The process of carotenoid J-aggregation inside nanocarriers is interfered with by the formation of kinetically stabilized H1 self-assemblies outside the micelles. Nanocarriers with encapsulated stable J-aggregates provide controlled release of carotenoid molecules to primary murine adipocytes.