Riboflavin-Targeted Drug Delivery

Utilizing stimuli-responsive nanoparticles to deliver and enhance the anti-tumor effects of bilirubin

Bilirubin (BR) is among the most potent endogenous antioxidants that originates from the heme catabolic pathway. Despite being considered as a dangerous and cytotoxic waste product at high concentrations, BR has potent antioxidant effects leading to the reduction of oxidative stress and inflammation, which play an important role in the development and progression of cancer. The purpose of this study is to introduce PEGylated BR nanoparticles (NPs), themselves or in combination with other anti-cancer agents. BR is effective when loaded into various nanoparticles and used in cancer therapy. Interestingly, BRNPs can be manipulated to create stimuli-responsive carriers providing a sustained and controlled, as well as on-demand, release of drug in response to internal or external factors such as reactive oxygen species, glutathione, light, enzymes, and acidic pH. This review suggests that BRNPs have the potential as tumor microenvironment-responsive delivery systems for effective targeting of various types of cancers.

Development and Evaluation of [68Ga]Ga-Labeled Riboflavin Derivative for RFVT3-Targeted PET Imaging of Melanoma in Mice

The limited progress in treatment options and the alarming survival rates in advanced melanoma emphasize the significant research importance of early melanoma diagnosis. RFVT3, a crucial protein at the core of energy metabolism reprogramming in melanoma, might play a pivotal role in early detection. In this study, [68Ga]Ga-NOTA-RF, based on riboflavin (RF), was rationally developed and validated, serving as an innovative tool for positron emission tomography (PET) imaging of RFVT3 expression in melanoma. The in vitro assays of RFVT3 specificity of [68Ga]Ga-NOTA-RF were performed on B16F10 melanoma cells. Then, PET imaging of melanoma was investigated in B16F10 allograft mouse models with varying volumes. Biodistribution studies are used to clarify the behavior of [68Ga]Ga-NOTA-RF in vivo. [68Ga]Ga-NOTA-RF was obtained with high radiochemical purity (>95%). A significant uptake (37.79 ± 6.86%, n = 4) of [68Ga]Ga-NOTA-RF was observed over time in B16F10 melanoma cells, which was significantly inhibited by RFVT3 inhibitors RF or methylene blue (MB), demonstrating the specific binding of [68Ga]Ga-NOTA-RF. At 60 min postinjection, the tumor-to-muscle (T/M) ratio of [68Ga]Ga-NOTA-RF was 4.03 ± 0.34, higher than that of the RF-blocked group (2.63 ± 0.19) and MB-blocked group (2.14 ± 0.20). The T/M ratios for three distinct tumor volumes-small (5 mm), medium (10 mm), and large (15 mm) were observed to be 5.25 ± 0.28, 4.03 ± 0.34, and 3.19 ± 0.55, respectively. The expression of RFVT3 was validated by immunohistochemical staining in various tumor models, with small B16F10 tumors exhibiting the highest expression. [68Ga]Ga-NOTA-RF demonstrates promising properties for the early diagnosis of melanoma and the examination of minute metastatic lesions, indicating its potential to assist in guiding clinical treatment decisions.

A Review of the Efficacy of Nanomaterial-Based Natural Photosensitizers to Overcome Multidrug Resistance in Cancer

Natural photosensitizers (PS) are compounds derived from nature, with photodynamic properties. Natural PSs have a similar action to that of commercial PSs, where cancer cell death occurs by necrosis, apoptosis, and autophagy through ROS generation. Natural PSs have garnered great interest over the last few decades because of their high biocompatibility and good photoactivity. Specific wavelengths could cause phytochemicals to produce harmful ROS for photodynamic therapy (PDT). However, natural PSs have some shortcomings, such as reduced solubility and lower uptake, making them less appropriate for PDT. Nanotechnology offers an opportunity to develop suitable carriers for various natural PSs for PDT applications. Various nanoparticles have been developed to improve the outcome with enhanced solubility, optical adsorption, and tumor targeting. Multidrug resistance (MDR) is a phenomenon in which tumor cells develop resistance to a wide range of structurally and functionally unrelated drugs. Over the last decade, several researchers have extensively studied the effect of natural PS-based photodynamic treatment (PDT) on MDR cells. Though the outcomes of clinical trials for natural PSs were inconclusive, significant advancement is still required before PSs can be used as a PDT agent for treating MDR tumors. This review addresses the increasing literature on MDR tumor progression and the efficacy of PDT, emphasizing the importance of developing new nano-based natural PSs in the fight against MDR that have the required features for an MDR tumor photosensitizing regimen.

Revitalising Riboflavin: Unveiling Its Timeless Significance in Human Physiology and Health

Since the early twentieth century, research on vitamins has revealed their therapeutic potential beyond their role as essential micronutrients. Riboflavin, known as vitamin B2, stands out for its unique characteristics. Despite numerous studies, riboflavin remains vital, with implications for human health. Abundantly present in various foods, riboflavin acts as a coenzyme in numerous enzymatic reactions crucial for human metabolism. Its role in energy production, erythrocyte synthesis, and vitamin metabolism underscores its importance in maintaining homeostasis. The impact of riboflavin extends to neurological function, skin health, and cardiovascular well-being, with adequate levels linked to reduced risks of various ailments. However, inadequate intake or physiological stress can lead to deficiency, a condition that poses serious health risks, including severe complications. This underscores the importance of maintaining sufficient levels of riboflavin for general wellness. The essential role of riboflavin in immune function further emphasises its significance for human health and vitality. This paper examines the diverse effects of riboflavin on health and stresses the importance of maintaining sufficient levels for overall well-being.

High internal phase double emulsions stabilized by modified pea protein-alginate complexes: Application for co-encapsulation of riboflavin and β-carotene

The application of many hydrophilic and hydrophobic nutraceuticals is limited by their poor solubility, chemical stability, and/or bioaccessibility. In this study, a novel Pickering high internal phase double emulsion co-stabilized by modified pea protein isolate (PPI) and sodium alginate (SA) was developed for the co-encapsulation of model hydrophilic (riboflavin) and hydrophobic (β-carotene) nutraceuticals. Initially, the effect of emulsifier type in the external water phase on emulsion formation and stability was examined, including commercial PPI (C-PPI), C-PPI-SA complex, homogenized and ultrasonicated PPI (HU-PPI), and HU-PPI-SA complex. The encapsulation and protective effects of these double emulsions on hydrophilic riboflavin and hydrophobic β-carotene were then evaluated. The results demonstrated that the thermal and storage stabilities of the double emulsion formulated from HU-PPI-SA were high, which was attributed to the formation of a thick biopolymer coating around the oil droplets, as well as thickening of the aqueous phase. Encapsulation significantly improved the photostability of the two nutraceuticals. The double emulsion formulated from HU-PPI-SA significantly improved the in vitro bioaccessibility of β-carotene, which was mainly attributed to inhibition of its chemical degradation under simulated acidic gastric conditions. The novel delivery system may therefore be used for the development of functional foods containing multiple nutraceuticals.

Mitoxantrone and abacavir: An ALK protein-targeted in silico proposal for the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a type of lung cancer associated with translocation of the EML4 and ALK genes on the short arm of chromosome 2. This leads to the development of an aberrant protein kinase with a deregulated catalytic domain, the cdALK+. Currently, different ALK inhibitors (iALKs) have been proposed to treat ALK+ NSCLC patients. However, the recent resistance to iALKs stimulates the exploration of new iALKs for NSCLC. Here, we describe an in silico approach to finding FDA-approved drugs that can be used by pharmacological repositioning as iALK. We used homology modelling to obtain a structural model of cdALK+ protein and then performed molecular docking and molecular dynamics of the complex cdALK+-iALKs to generate the pharmacophore model. The pharmacophore was used to identify potential iALKs from FDA-approved drugs library by ligand-based virtual screening. Four pharmacophores with different atomistic characteristics were generated, resulting in six drugs that satisfied the proposed atomistic positions and coupled at the ATP-binding site. Mitoxantrone, riboflavin and abacavir exhibit the best interaction energies with 228.29, 165.40 and 133.48 KJoul/mol respectively. In addition, the special literature proposed these drugs for other types of diseases due to pharmacological repositioning. This study proposes FDA-approved drugs with ALK inhibitory characteristics. Moreover, we identified pharmacophores sites that can be tested with other pharmacological libraries.

Development of radiotracers for riboflavin transporter 3 imaging in diseases-A brief overview

Riboflavin (RF, vitamin B2) plays a key role in metabolic oxidation-reduction reactions, especially in the mitochondrial reprogramming of energy metabolism. Riboflavin transporter 3 (RFVT3) is a vital section of the mitochondrial network and involved in riboflavin homeostasis and production of adenosine triphosphate (ATP). The abnormal expression of RFVT3 is closely associated with the occurrence and progression of multiple diseases. Therefore, it is vital to understand the riboflavin internalization pathway under pathological conditions by addressing the abnormal expression of RFVT3, which could be a highly valuable biomarker for the early diagnosis and effective therapy of various diseases.

Riboflavin interactions with the chicken isolated carrier protein

Riboflavin, a member of the B vitamin family, is a water-soluble vitamin that participates in energy metabolism processes via two coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), in oxidized and reduced forms. Low levels of riboflavin have been associated with growth and developmental problems. In an effort to investigate the role of hydrogen bonding in the interactions between riboflavin and chicken riboflavin binding protein, the solid state geometry characteristics of a riboflavin derivative stripped of hydroxyl groups except the primary one, N-(6'-hydroxyhexyl)isoalloxazine, were investigated and found that π-stacking and hydrogen bonding involving the isoalloxazine rings are the primary intermolecular interactions. Subsequent comparative fluorescence studies showed that at neutral pH, in presence of the protein, quenching of N-(6'-hydroxyhexyl)isoalloxazine and riboflavin occurred similarly suggesting that the hydroxyl groups were not a key component of the vitamin protein interactions in the binding pocket.

Molecular Engineering of E. coli Bacterioferritin: A Versatile Nanodimensional Protein Cage

Currently, intense interest is focused on the discovery and application of new multisubunit cage proteins and spherical virus capsids to the fields of bionanotechnology, drug delivery, and diagnostic imaging as their internal cavities can serve as hosts for fluorophores or bioactive molecular cargo. Bacterioferritin is unusual in the ferritin protein superfamily of iron-storage cage proteins in that it contains twelve heme cofactors and is homomeric. The goal of the present study is to expand the capabilities of ferritins by developing new approaches to molecular cargo encapsulation employing bacterioferritin. Two strategies were explored to control the encapsulation of a diverse range of molecular guests compared to random entrapment, a predominant strategy employed in this area. The first was the inclusion of histidine-tag peptide fusion sequences within the internal cavity of bacterioferritin. This approach allowed for the successful and controlled encapsulation of a fluorescent dye, a protein (fluorescently labeled streptavidin), or a 5 nm gold nanoparticle. The second strategy, termed the heme-dependent cassette strategy, involved the substitution of the native heme with heme analogs attached to (i) fluorescent dyes or (ii) nickel-nitrilotriacetate (NTA) groups (which allowed for controllable encapsulation of a histidine-tagged green fluorescent protein). An in silico docking approach identified several small molecules able to replace the heme and capable of controlling the quaternary structure of the protein. A transglutaminase-based chemoenzymatic approach to surface modification of this cage protein was also accomplished, allowing for future nanoparticle targeting. This research presents novel strategies to control a diverse set of molecular encapsulations and adds a further level of sophistication to internal protein cavity engineering.

Application of molecular dynamics simulation in self-assembled cancer nanomedicine

Self-assembled nanomedicine holds great potential in cancer theragnostic. The structures and dynamics of nanomedicine can be affected by a variety of non-covalent interactions, so it is essential to ensure the self-assembly process at atomic level. Molecular dynamics (MD) simulation is a key technology to link microcosm and macroscale. Along with the rapid development of computational power and simulation methods, scientists could simulate the specific process of intermolecular interactions. Thus, some experimental observations could be explained at microscopic level and the nanomedicine synthesis process would have traces to follow. This review not only outlines the concept, basic principle, and the parameter setting of MD simulation, but also highlights the recent progress in MD simulation for self-assembled cancer nanomedicine. In addition, the physicochemical parameters of self-assembly structure and interaction between various assembled molecules under MD simulation are also discussed. Therefore, this review will help advanced and novice researchers to quickly zoom in on fundamental information and gather some thought-provoking ideas to advance this subfield of self-assembled cancer nanomedicine.

Enhancement of the immune response via the facilitation of dendritic cell maturation by CD-205 Receptor-mediated Long-circling liposomes acting as an antigen and astragalus polysaccharide delivery system

CD-205 receptor-mediated dendritic cell (DC) targeting liposomes are commonly used as a delivery system for inducing a strong T-cell immune response or specific immune tolerance. This delivery system can carry both the antigen and adjuvant, thereby modulating DC maturation and also activating the T-cell response. In order to maximize the desired therapeutic effects of Astragalus polysaccharides (APS) and induce an efficient cellular and humoral immune response against the antigen, ovalbumin (OVA) and APS were encapsulated in long-circling liposomes conjugated with anti-CD-205 receptor antibodies to produce CD-205-targeted liposomes (iLPSM). We explored using a series of experiments evaluating the targeting efficiency of iLPSM. In vitro, iLPSM nanoparticles promoted the proliferation of macrophages, and the nanoparticles were rapidly phagocytized by macrophages. In vivo, iLPSM significantly improved the antibody titers of OVA-specific IgG and IgG, isotypes cytokine production, and T and B lymphocyte differentiation. Furthermore, iLPSM facilitated the maturation of DCs. In addition, iLPSM nanoparticles could prolong the retention time of nanoparticles at the injection site, leading to a strong, sustained immune response. These results show that the CD-205 antibody successfully binds to the corresponding cell receptor.

Acetyl-Click Screening Platform Identifies Small-Molecule Inhibitors of Histone Acetyltransferase 1 (HAT1)

HAT1 is a central regulator of chromatin synthesis that acetylates nascent histone H4. To ascertain whether targeting HAT1 is a viable anticancer treatment strategy, we sought to identify small-molecule inhibitors of HAT1 by developing a high-throughput HAT1 acetyl-click assay. Screening of small-molecule libraries led to the discovery of multiple riboflavin analogs that inhibited HAT1 enzymatic activity. Compounds were refined by synthesis and testing of over 70 analogs, which yielded structure-activity relationships. The isoalloxazine core was required for enzymatic inhibition, whereas modifications of the ribityl side chain improved enzymatic potency and cellular growth suppression. One compound (JG-2016 [24a]) showed relative specificity toward HAT1 compared to other acetyltransferases, suppressed the growth of human cancer cell lines, impaired enzymatic activity in cellulo, and interfered with tumor growth. This is the first report of a small-molecule inhibitor of the HAT1 enzyme complex and represents a step toward targeting this pathway for cancer therapy.

Characterization of a Riboflavin-Producing Mutant of Bacillus subtilis Isolated by Droplet-Based Microfluidics Screening

Bacillus subtilis is one of the commonly used industrial strains for riboflavin production. High-throughput screening is useful in biotechnology, but there are still an insufficient number of articles focusing on improving the riboflavin production of B. subtilis by this powerful tool. With droplet-based microfluidics technology, single cells can be encapsulated in droplets. The screening can be carried out by detecting the fluorescence intensity of secreted riboflavin. Thus, an efficient and high-throughput screening method suitable for riboflavin production strain improvement could be established. In this study, droplet-based microfluidics screening was applied, and a more competitive riboflavin producer U3 was selected from the random mutation library of strain S1. The riboflavin production and biomass of U3 were higher than that of S1 in flask fermentation. In addition, the results of fed-batch fermentation showed that the riboflavin production of U3 was 24.3 g/L, an 18% increase compared with the parent strain S1 (20.6 g/L), and the yield (g riboflavin/100 g glucose) increased by 19%, from 7.3 (S1) to 8.7 (U3). Two mutations of U3 (sinR^G89R and icd^D28E) were identified through whole genome sequencing and comparison. Then they were introduced into BS168DR (parent of S1) for further analysis, which also caused riboflavin production to increase. This paper provides protocols for screening riboflavin-producing B. subtilis with droplet-based microfluidics technology and reveals mutations in riboflavin overproduction strains.

High serum riboflavin is associated with the risk of sporadic colorectal cancer

BACKGROUND

Experimental results indicate that riboflavin is involved in tumorigenesis. Data regarding the relationship between riboflavin and colorectal cancer (CRC) are limited, and findings vary between observational studies.

DESIGN

This was a case-control retrospective study.

OBJECTIVE

This study aimed to evaluate the associations between serum riboflavin level and sporadic CRC risk.

METHODS

In total, 389 participants were enrolled in this study - including 83 CRC patients without family history and 306 healthy controls - between January 2020 and March 2021 at the Department of Colorectal Surgery and Endoscope Center at Xinhua Hospital, Shanghai Jiao Tong University School of Medicine. Age, sex, body mass index, history of polyps, disease conditions (e.g., diabetes), medications, and eight other vitamins were used as confounding factors. Adjusted smoothing spline plots, subgroup analysis, and multivariate logistic regression analysis were conducted to estimate the relative risk between serum riboflavin levels and sporadic CRC risk. After fully adjusting for the confounding factors, an increased risk of colorectal cancer was suggested for individuals with higher levels of serum riboflavin (OR = 1.08 (1.01, 1.15), p = 0.03) in a dose-response relationship.

CONCLUSIONS

Our results support the hypothesis that higher levels of riboflavin may play a role in facilitating colorectal carcinogenesis. The finding of high levels of circulating riboflavin in patients with CRC warrants further investigation.

Design, Synthesis, Characterization, and Evaluation of the Anti-HT-29 Colorectal Cell Line Activity of Novel 8-Oxyquinolinate-Platinum(II)-Loaded Nanostructured Lipid Carriers Targeted with Riboflavin

Colorectal cancer is occasionally called colon or rectal cancer, depending on where cancer begins to form, and is the second leading cause of cancer death among both men and women. The platinum-based [PtCl(8-O-quinolinate)(dmso)] (8-QO-Pt) compound has demonstrated encouraging anticancer activity. Three different systems of 8-QO-Pt-encapsulated nanostructured lipid carriers (NLCs) with riboflavin (RFV) were investigated. NLCs of myristyl myristate were synthesized by ultrasonication in the presence of RFV. RFV-decorated nanoparticles displayed a spherical shape and a narrow size dispersion in the range of 144-175 nm mean particle diameter. The 8-QO-Pt-loaded formulations of NLC/RFV with more than 70% encapsulation efficiency showed sustained in vitro release for 24 h. Cytotoxicity, cell uptake, and apoptosis were evaluated in the HT-29 human colorectal adenocarcinoma cell line. The results revealed that 8-QO-Pt-loaded formulations of NLC/RFV showed higher cytotoxicity than the free 8-QO-Pt compound at 5.0 µM. All three systems exhibited different levels of cellular internalization. Moreover, the hemotoxicity assay showed the safety profile of the formulations (less than 3.7%). Taken together, RFV-targeted NLC systems for drug delivery have been investigated for the first time in our study and the results are promising for the future of chemotherapy in colon cancer treatment.

Two-photon photodynamic therapy based on FRET using tumor-cell targeted riboflavin conjugated graphene quantum dot

The photodynamic therapy (PDT) is considered as a noninvasive and photo-controlled treatment for various cancers. However, its potential is not fully developed as current clinically approved photosensitizers (PSs) mainly absorb the light in the UV-visible region (less than 700 nm), where the depth of penetration is inadequate for reaching tumor cells under deeper tissue layers. Furthermore, the lack of specific accumulation capability of the conventional PSs in the tumor cells may cause serious toxicity and low treatment efficiency. To address these problems, riboflavin (Rf) conjugated and amine-functionalized nitrogen-doped graphene quantum dots (am-N-GQD) are herein proposed. Rf functions as both photosensitizer and targeting ligand by indirect excitation through intra-particle fluorescence resonance energy transfer (FRET) via two-photon (TP) excited am-N-GQD, to enhance the treatment depth, and further am-N-GQD-Rf accumulation in cancer cells using Rf transporter family (RFVTs) and Rf carrier proteins (RCPs). The one-photon (OP) and two-photon(TP)-PDT effect and cellular internalization ability of the am-N-GQD-Rf were investigated in vitro in different cancel cell lines. Besides the excellent cellular uptake as well TP-PDT capability, the superior biocompatibility of am-N-GQD-Rf in vitro makes it promising candidate in PDT.

Single-step extraction of small-diameter single-walled carbon nanotubes in the presence of riboflavin

We propose a novel approach to disperse and extract small-diameter single-walled carbon nanotubes (SWCNTs) using an aqueous solution of riboflavin and Sephacryl gel. The extraction of small-diameter semiconducting SWCNTs was observed, regardless of the initial diameter distribution of the SWCNTs. Dispersion of SWCNTs occurs due to the adsorption of π-conjugated isoalloxazine moieties on the surface of small-diameter nanotubes and interactions between hydroxy groups of ribityl chains with water. During the SWCNT extraction, specific adsorption of riboflavin to SWCNTs leads to the minimization of interactions between the SWCNTs and gel media. Our experimental findings are supported by ab initio calculations demonstrating the impact of the riboflavin wrapping pattern around the SWCNTs on their interaction with the allyl dextran gel.

In silico investigation on structure-function relationship of members belonging to the human SLC52 transporter family

Riboflavin is an essential water-soluble vitamin that needs to be provided through the diet because of the conversion into flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), important cofactors in hundreds of flavoenzymes. The adsorption and distribution of riboflavin is mediated by transmembrane transporters of the SLC52 family, namely RFVT1-3, whose mutations are mainly associated with two diseases, MADD and the Brown-Vialetto-Van Laere syndrome. Interest in RFVTs as pharmacological targets has increased in the last few years due to their overexpression in several cancer cells, which can be exploited both by blocking the uptake of riboflavin into the cancerous cells, and by performing cancer targeted delivery of drugs with a high affinity for RFVTs. In this work, we propose three-dimensional structural models for all three human riboflavin transporters obtained by state-of-the-art artificial intelligence-based methods, which were then further refined with molecular dynamics simulations. Furthermore, two of the most notable mutations concerning RFVT2 and RFVT3 (W31S and N21S, respectively) were investigated studying the interactions between the wild-type and mutated transporters with riboflavin.

Riboflavin-Promoted In Situ Photoactivation of Dihydroalkaloid Prodrugs for Cancer Therapy

Cancer therapies usually suffer from poor targeting ability and serious side effects. Photoactivatable cancer therapy has the significant advantage of a high spatiotemporal resolution, but most photoactivatable prodrugs require decoration with stoichiometric photocleavable groups, which are only responsive to ultraviolet irradiation and suffer from low reaction efficiency. To tackle these challenges, we herein propose a photoactivation strategy with biogenic riboflavin as the photosensitizer to promote the in situ transformation of noncytotoxic dihydroalkaloid prodrugs dihydrochelerythrine (DHCHE), dihydrosanguinarine (DHSAN), and dihydronitidine (DHNIT) into anticancer alkaloid drugs chelerythrine (CHE), sanguinarine (SAN), and nitidine (NIT), respectively, which can efficiently kill cancer cells and inhibit in vivo tumor growth. Meanwhile, the photoactivatable transformation can be in situ monitored by green-to-red fluorescence conversion, which will contribute to easy controlling of the therapeutic dose. The proposed photoactivatable transformation mechanism was also explored by density functional theory (DFT) calculations. We believe this riboflavin-promoted and imaging-guided photoactivation strategy is promising for precise cancer therapy.

Organogold(III) Complexes Display Conditional Photoactivities: Evolving From Photodynamic into Photoactivated Chemotherapy in Response to O2 Consumption for Robust Cancer Therapy

Photodynamic therapy (PDT) is a spatiotemporally controllable, powerful approach in combating cancers but suffers from low activity under hypoxia, whereas photoactivated chemotherapy (PACT) operates in an O₂ -independent manner but compromises the ability to harness O₂ for potent photosensitization. Herein we report that cyclometalated gold(III)-alkyne complexes display a PDT-to-PACT evolving photoactivity for efficient cancer treatment. On the one hand, the gold(III) complexes can act as dual photosensitizers and substrates, leading to conditional PDT activity in oxygenated condition that progresses to highly efficient PACT (ϕ up to 0.63) when O₂ is depleted in solution and under cellular environment. On the other hand, the conditional PDT-to-PACT reactivity can be triggered by external photosensitizers in a similar manner in vitro and in vivo, giving additional tumor-selectivity and/or deep tissue penetration by red-light irradiation that leads to robust anticancer efficacy.

Chitosan/Lactic Acid Systems: Liquid Crystalline Behavior, Rheological Properties, and Riboflavin Release In Vitro

Chitosan or its derivatives exhibit lyotropic liquid crystalline mesophases under certain conditions due to its semi-rigid structures. This work describes the development of chitosan-based biocompatible systems that include new components: lactic acid and non-ionic surfactants. Polarized optical microscopy studies revealed that these systems are capable of forming gels or lyotropic liquid crystals (LLCs) in a certain range of chitosan and lactic acid concentrations. According to the viscosity studies, the rheological flow of the LLCs can be accurately described by the Casson flow model. The intermolecular interactions of the LLC components were studied by FTIR spectroscopy. According to the FTIR data, hydrogen bonding is supposed to be responsible for the formation of the LLCs. In the studied systems, this LLC complex exists as the [ChitH+·CH3-CH(OH)-COO-] ion pair. The studied gel and LLCs were shown to possess the most prolonged release capabilities for riboflavin among similar binary LLC systems. The supramolecular organization and rheological characteristics of the studied chitosan-based systems were found to affect the release of riboflavin.

Hyaluronic acid coated spinel ferrite for combination of chemo and photodynamic therapy: Green synthesis, characterization, and in vitro and in vivo biocompatibility study

In this project, different photosensitizers were prepared using different ratios of nickel, manganese, and iron. Then, multiple analysis were performed to evaluate their efficiency, and the most suitable one was used to be coated by hyaluronic acid to improve the nano-platform's biocompatibility and target ability. Moreover, another chemical targeting agent (riboflavin) was used to further improve the target ability of the prepared nano-platform. Different spectroscopies and thermal analysis were used to determine the physical and chemical characteristics of the prepared nano-platform. Also, in order to determine the biocompatibility of the nano-platform, in vitro and in vivo tests such as blood hemolysis, blood aggregation and lethal dose were performed. Then, an anti-cancer agent (curcumin) was loaded on the selected nano-platform to makes us able utilizing the synergistic effect of chemotherapy and photodynamic therapy simultaneously. Finally, the cell cytotoxicity results showed that the prepared nano-platform had a great anti-cancer potential which can make it a great candidate as a dual photo and chemo therapy agent for treatment of breast cancers.

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra- and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP-cell interaction. This review provides a detailed overview of the available technologies focusing on cell-NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health.

Riboflavin-citrate conjugate multicore SPIONs with enhanced magnetic responses and cellular uptake in breast cancer cells

Breast cancer accounts for up to 10% of the newly diagnosed cancer cases worldwide, making it the most common cancer found in women. The use of superparamagnetic iron oxide nanoparticles (SPIONs) has been beneficial in the advancement of contrast agents and magnetic hyperthermia (MH) for the diagnosis and treatment of cancers. To achieve delivery of SPIONs to cancer cells, surface functionalization with specific ligands are required. Riboflavin carrier protein (RCP) has been identified as an alternative target for breast cancer cells. Here, we report a novel riboflavin (Rf)-based ligand that provides SPIONs with enhanced colloidal stability and high uptake potential in breast cancer cells. This is achieved by synthesizing an Rf-citrate ligand. The ligand was tested in a multicore SPION system, and affinity to RCP was assessed by isothermal titration calorimetry which showed a specific, entropy-driven binding. MRI and MH responses of the coated Rf-SPIONs were tested to evaluate the suitability of this system as a theranostic platform. Finally, interaction of the Rf-SPIONs with breast cancer cells was evaluated by in vitro cellular uptake in MCF-7 breast cancer cells. The overall characterization of the Rf-SPIONs highlighted the excellent performance of this platform for theranostic applications in breast cancer.

Improving the self-assembly of bioresponsive nanocarriers by engineering doped nanocarbons: a computational atomistic insight

Here, molecular dynamics (MD) simulations were employed to explore the self-assembly of polymers and docetaxel (DTX) as an anticancer drug in the presence of nitrogen, phosphorous, and boron-nitrogen incorporated graphene and fullerene. The electrostatic potential and the Gibbs free energy of the self-assembled materials were used to optimize the atomic doping percentage of the N- and P-doped formulations at 10% and 50%, respectively. Poly lactic-glycolic acid (PLGA)- polyethylene glycol (PEG)-based polymeric nanoparticles were assembled in the presence of nanocarbons in the common (corresponding to the bulk environment) and interface of organic/aqueous solutions (corresponding to the microfluidic environment). Assessment of the modeling results (e.g., size, hydrophobicity, and energy) indicated that among the nanocarbons, the N-doped graphene nanosheet in the interface method created more stable polymeric nanoparticles (PNPs). Energy analysis demonstrated that doping with nanocarbons increased the electrostatic interaction energy in the self-assembly process. On the other hand, the fullerene-based nanocarbons promoted van der Waals intramolecular interactions in the PNPs. Next, the selected N-doped graphene nanosheet was utilized to prepare nanoparticles and explore the physicochemical properties of the nanosheets in the permeation of the resultant nanoparticles through cell-based lipid bilayer membranes. In agreement with the previous results, the N-graphene assisted PNP in the interface method and was translocated into and through the cell membrane with more stable interactions. In summary, the present MD simulation results demonstrated the success of 2D graphene dopants in the nucleation and growth of PLGA-based nanoparticles for improving anticancer drug delivery to cells, establishing new promising materials and a way to assess their performance that should be further studied.

Flavin-adenine-dinucleotide gold complex nanoparticles: chemical modeling design, physico-chemical assessment and perspectives in nanomedicine

Flavoproteins play an important role in the regulatory process of cell life, and they are involved in several redox reactions that regulate the metabolism of carbohydrates, amino acids, and lipids. The development of effective drug delivery systems is one of the major challenges in the fight against cancer. This study involves a nanomedicine pathway to encapsulate the cofactor flavin adenine dinucleotide (FAD) using polymeric gold nanoparticles (PEG-AuNPs) through two chemical methods of functionalization (chelation (IN); carbodiimide chemistry (ON)). These hybrid gold nanoparticles and their precursors were characterized by analytical techniques (Raman, UV-Vis, and H1-NMR spectroscopy and transmission electron microscopy (TEM)) which confirmed the grafting of the cofactor agent. The results of the computational studies (Density Functional Theory (DFT)) were in agreement with the experimental observations. We also monitored the interaction of our hybrid nanoparticle systems with small aptamers (APT) in order to validate the hypotheses on the biomolecular mechanisms and also investigate their biological efficiency on pancreatic cancer cells (MIAPaCa-2 cells).

Microbial production of riboflavin: Biotechnological advances and perspectives

Riboflavin is an essential nutrient for humans and animals, and its derivatives flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are cofactors in the cells. Therefore, riboflavin and its derivatives are widely used in the food, pharmaceutical, nutraceutical and cosmetic industries. Advances in biotechnology have led to a complete shift in the commercial production of riboflavin from chemical synthesis to microbial fermentation. In this review, we provide a comprehensive review of biotechnologies that enhance riboflavin production in microorganisms, as well as representative examples. Firstly, the synthesis pathways and metabolic regulatory processes of riboflavin in microorganisms; and the current strategies and methods of metabolic engineering for riboflavin production are systematically summarized and compared. Secondly, the using of systematic metabolic engineering strategies to enhance riboflavin production is discussed, including laboratory evolution, histological analysis and high-throughput screening. Finally, the challenges for efficient microbial production of riboflavin and the strategies to overcome these challenges are prospected.

Ultrasmall superparamagnetic iron oxide nanoparticles: A next generation contrast agent for magnetic resonance imaging

As a research hotspot, the development of magnetic resonance imaging (MRI) contrast agents has attracted great attention over the past decades for improving the accuracy of diagnosis. Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles with core diameter smaller than 5.0 nm are expected to become a next generation of contrast agents owing to their excellent MRI performance, long blood circulation time upon proper surface modification, renal clearance capacity, and remarkable biosafety profile. On top of these merits, USPIO nanoparticles are used for developing not only T₁ contrast agents, but also T₂ /T₁ switchable contrast agents via assembly/disassembly approaches. In recent years, as a new type of contrast agents, USPIO nanoparticles have shown considerable applications in the diagnosis of various diseases such as vascular pathological changes and inflammations apart from malignant tumors. In this review, we are focusing on the state-of-the-art developments and the latest applications of USPIO nanoparticles as MRI contrast agents to discuss their advantages and future prospects. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Biotinylated Mn3O4 nanocuboids for targeted delivery of gemcitabine hydrochloride to breast cancer and MRI applications

Multifunctional nanocarriers have been found as potential candidate for the targeted drug delivery and imaging applications. Herein, we have developed a biocompatible and pH-responsive manganese oxide nanocuboid system, surface modified with poly (ethylene glycol) bis(amine) and functionalized with biotin (Biotin-PEG-MNCs), for an efficient and targeted delivery of an anticancer drug (gemcitabine, GEM) to the human breast cancer cells. GEM-loaded Biotin-PEG@MNCs showed high drug loading efficiency, controlled release of GEM and excellent storage stability in the physiological buffers and different temperature conditions. GEM-loaded Biotin-PEG@MNCs showed dose- and time-dependent decrease in the viability of human breast cancer cells. Further, it exhibited significantly higher cell growth inhibition than pure GEM which suggested that Biotin-PEG@MNCs has efficiently delivered the GEM into cancerous cells. The role of biotin in the uptake was proved by the competitive binding-based cellular uptake study. A significant decrease in the amount of manganese was observed in biotin pre-treated cancer cells as compared to biotin untreated cancer cells. In MRI studies, Biotin-PEG-MNCs showed both longitudinal and transverse relaxivity about 0.091 and 7.66 mM^-1 s^-1 at 3.0 T MRI scanner, respectively. Overall, the developed Biotin-PEG-MNCs presents a significant potential in formulation development for cancer treatment via targeted drug delivery and enhanced MRI contrast imaging properties.

Flavin-Conjugated Nanobombs: Key Structural Requirements Governing Their Self-Assemblies' Morphologies

In contrast to artificial molecules, natural photosensitizers have the benefit of excellent toxicity profiles and of life-compatible activating energy ranges. Flavins are such photosensitizers that were selected by nature in a plethora of light-triggered biochemical reactions. Flavin-rich nanoparticles could thus emerge as promising tools in photodynamic therapies and in active-targeting drug delivery. Self-assembled flavin-conjugated phospholipids improve the pharmacokinetics of natural flavins and, in the case of controlled morphologies, reduce photobleaching phenomena. The current article presents a proof of concept for the design of riboflavin-rich nanoparticles of tunable morphology from multilamellar patches to vesicular self-assemblies. Coarse-grained simulations of the self-assembling process revealed the key interactions governing the obtained nanomaterials and successfully guided the synthesis of new flavin-conjugates of predictable self-assembly. The obtained flavin-based liposomes had a 65 nm hydrodynamic diameter, were stable, and showed potential photosensitizer activity.

Molecular Delivery of Cytotoxic Agents via Integrin Activation

Integrins are cell adhesion receptors overexpressed in tumor cells. A direct inhibition of integrins was investigated, but the best inhibitors performed poorly in clinical trials. A gained attention towards these receptors arouse because they could be target for a selective transport of cytotoxic agents. Several active-targeting systems have been developed to use integrins as a selective cell entrance for some antitumor agents. The aim of this review paper is to report on the most recent results on covalent conjugates between integrin ligands and antitumor drugs. Cytotoxic drugs thus conjugated through specific linker to integrin ligands, mainly RGD peptides, demonstrated that the covalent conjugates were more selective against tumor cells and hopefully with fewer side effects than the free drugs.

Effect of ligand conjugation site on the micellization of Bio-Targeted PLGA-Based nanohybrids: A computational biology approach

In this study, the effect of ligand binding position on the polymeric nanoparticles (NPs) is based on poly(lactic-co-glycolic acid) (PLGA) with two different polymer chain length at the atomistic level was presented. We explored the conjugation of riboflavin (RF) ligand from the end of the ribityl chain (N-10) to the polymer strands as well as from the amine group on the isoalloxazine head (N-3). The energy interactions for all samples revealed that the NPs containing ligands from N-10 positions have higher total attraction energies and lower stability in comparison with their peers conjugated from N-3. As NPs containing RF conjugated from N-3 exhibit the lower energy level with 20% and 10% of RF-containing composition for lower and higher. The introduction of RF from the N-10 position in any composition has increased the energy level of nanocarriers. The results of Gibb's free energy confirm the interatomic interaction energies trend where the lowest Gibbs free energy level for N-3 NPs occurs at 20 and 10% of RF-containing polymer content for PLGA10- and PLGA11- based NPs. Furthermore, with N-10 samples based on both polymers, non-targeted models form the stablest particles in each category. These findings are further confirmed with molecular docking analysis which revealed affinity energy of RF toward polymer chain from N-3 and N-10 are -981.57 kJ/mole and -298.23 kJ/mole, respectively. This in-silico study paves the new way for molecular engineering of the bio-responsive PLGA-PEG-RF micelles and can be used to nanoscale tunning of smart carriers used in cancer treatment.Communicated by Ramaswamy H. Sarma.

Influence of Riboflavin Targeting on Tumor Accumulation and Internalization of Peptostar Based Drug Delivery Systems

Riboflavin carrier protein (RCP) and riboflavin transporters (RFVTs) have been reported to be highly overexpressed in various cancer cells. Hence, targeting RCP and RFVTs using riboflavin may enhance tumor accumulation and internalization of drug delivery systems. To test this hypothesis, butyl-based 3-arm peptostar polymers were synthesized consisting of a lysine core (10 units per arm) and a sarcosine shell (100 units per arm). The end groups of the arms and the core were successfully modified with riboflavin and the Cy5.5 fluorescent dye, respectively. While in phosphate buffered saline the functionalized peptostars showed a bimodal behavior and formed supramolecular structures over time, they were stable in the serum maintaining their hydrodynamic diameter of 12 nm. Moreover, the polymers were biocompatible and the uptake of riboflavin targeted peptostars in A431 and PC3 cells was higher than in nontargeted controls and could be blocked competitively. In vivo, the polymers showed a moderate passive tumor accumulation, which was not significantly different between targeted and nontargeted peptostars. Nonetheless, at the histological level, internalization into tumor cells was strongly enhanced for the riboflavin-targeted peptostars. Based on these results, we conclude that passive accumulation is dominating the accumulation of peptostars, while tumor cell internalization is strongly promoted by riboflavin targeting.

Molecular engineering of the last-generation CNTs in smart cancer therapy by grafting PEG-PLGA-riboflavin

In this work, the effect of environment and additives on the self-assembly and delivery of doxorubicin (DOX) have been studied. A microfluidic system with better control over molecular interactions and high surface to volume ratio has superior performance in comparison to the bulk system. Moreover, carbon nanotube (CNT) and CNT-doped structures have a high surface area to incorporate the DOX molecules into a polymer and the presence of functional groups can influence the polymer-drug interactions. In this work, the interactions of DOX with both the polymeric complex and the nanotube structure have been investigated. For quantification of the interactions, H-bonding, gyration radius, root-mean-square deviation (RMSD), Gibbs free energy, radial distribution function (RDF), energy, and Solvent Accessible Surface Area (SASA) analyses have been performed. The most stable micelle-DOX interaction is attributed to the presence of BCN in the microfluidic system according to the gyration radius and RMSD. Meanwhile, for DOX-doped CNT interaction the phosphorus-doped CNT in the microfluidic system is more stable. The highest electrostatic interaction can be seen between polymeric micelles and DOX in the presence of BCN. For nanotube-drug interaction, phosphorus-doped carbon nanotubes in the microfluidic system have the largest electrostatic interaction with the DOX. RDF results show that in the microfluidic system, nanotube-DOX affinity is larger than that of nanotube-micelle.

Cancer Nanomedicine

This Special Issue on Cancer Nanomedicine within Cancers brings together 46 cutting-edge papers covering research within the field along with insightful reviews and opinions reflecting our community [...].

Investigating the Photochemistry of C7 and C8 Functionalized N(5)-Ethyl-flavinium Cation: A Computational Study

Flavins are a diverse set of compounds with a wide variety of biological and nonbiological applications. Applications of flavins receiving attention recently consist of electro- and photocatalytic oxidation of substrates for organic synthesis, bioengineered nanotechnology, and water splitting catalysts, among others. While there is vast knowledge regarding the structure-property relationships of flavins and their electrochemistry, there is much less work elucidating the structure property relationships as they pertain to flavinium photochemistry. Herein, we report the effect of molecular tailoring on the molecular properties of N(5)-ethyl-flavinium cation (Et-Fl⁺), a derivative of the biocatalytic coenzyme riboflavin, by incorporating electron withdrawing and donating groups at the C7 and C8 position of the isoalloxazine ring. The presence of electron withdrawing groups at the C8 position caused a red shift in the absorption spectrum, while the electron donating groups caused a blue shift. Functionalization at the C7 position had the opposite effect on the absorption spectrum. The effects of single substitution were relatively negated with simultaneous functionalization at both the C8 and C7 positions. Difference density plots indicate no change in the nature of the S₁ excited state, which was confirmed by optimization of the excited state geometries. The results presented in this study indicate that functionalization of the isoalloxazine unit affects the photophysical properties of N(5)-ethyl-flavinium cations.