Interaction Of Plasma Proteins Research Articles

Interaction of Serum and Plasma Proteins with Polyelectrolyte Microparticles with Core/Shell and Shell-Only Structures.

Polyelectrolyte microparticles (MPs) synthesized on calcium carbonate cores are considered a promising basis for new drug delivery systems. It is known that microparticles entering a physiological environment absorb proteins on their surface, which can change the properties of the microparticles and alter their functional activity. This study aimed to compare the compositions of the adsorbed protein layer formed on microparticles with the core/shell and shell structures obtained by layer-by-layer deposition. The difference in the microparticle structure was associated with changes in their surface topography and ζ-potential. These microparticles were incubated with human serum or plasma at 37°C for 24 h. The adsorbed proteins were eluted and analyzed by means of SDS-PAGE. The protein composition of the eluates was determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS); a total of 357 proteins were identified, and 183 of them were detected in all samples. Our results demonstrate that the relative abundance of proteins of different functional groups (immunoglobulins, complement proteins, and apolipoproteins) varied depending on the structure and surface characteristics of the polyelectrolyte microparticles and the incubation medium. Our findings expand the understanding of the influence of the physicochemical properties of the microparticles on their interaction with proteins, which can help to improve the design of microparticles for drug delivery.

Variations in the inner core affect the pharmacokinetics of indomethacin-encapsulated polymeric micelles

Hydrophobic ion pairing (HIP) is a drug encapsulation technology that uses electrostatic interactions between a drug and an additive. However, although polymeric micelles can encapsulate hydrophobic drugs in the core, the encapsulated drug often leaks. Therefore, we designed polymeric micelles with HIP functionalized in a hydrophobic inner core using three diblock copolymers comprising polypeptides with different ratios of polar and hydrophobic amino acids and polyethylene glycol (PEG) to encapsulate indomethacin (IND). The three IND-encapsulated HIP micelles showed different area under the curve (AUC) values as an index of blood retention after intravenous injection in mice. Despite having the same PEG shell, IND-PEG-poly(H/F)n showed a 1.56-fold higher AUC than IND-PEG-poly(D/F)n. PEG interface morphologies were evaluated to determine the differences in pharmacokinetic parameters caused by changes in inner core HIP patterns. The micellarized diblock copolymer was desorbed from IND-PEG-poly(D/F)n due to electrostatic repulsion between IND and the diblock copolymer comprising aspartic acid. Our results suggest that changes in the HIP patterns of the micelle inner core affected the PEG interface morphologies, such as PEG density and diblock copolymer desorption from micelles. These phenomena might lead to changes in the interaction of plasma proteins and drug dispositions.

Interaction of Human Serum and Plasma Proteins with Polyelectrolyte Microcapsules of Different Structures

Interaction of Human Serum and Plasma Proteins with Polyelectrolyte Microcapsules of Different Structures

Role of Haptoglobin in Protecting the Toxic Effects of Hemoglobin in Various Pathologies

The review presents modern domestic and foreign literature data on the blood plasma protein haptoglobin, its structure, synthesis, function and interaction with hemoglobin. The ability of haptoglobin in interaction with hemoglobin to reduce the toxic effect of the latter is shown. Clinical studies of such interaction in various pathological conditions such as diabetes mellitus, sickle cell anemia, malaria, sepsis, etc. are described. It is noted that the development of new haptoglobin derivatives can contribute to the prevention of hemoglobin toxicity in hemolytic diseases.

Artificial Base-Directed In Vivo Assembly of an Albumin-siRNA Complex for Tumor-Targeting Delivery.

RNA interference (RNAi) mediated by short interfering RNA (siRNA) is a promising method for cancer treatment, but the clinical application is hampered by several limitations, including metabolic instability, lack of tumor specificity, and poor cellular uptake. To meet these challenges, we have explored the possibility of structure modification of siRNA with artificial bases for property optimization. A series of siRNAs functionalized with different numbers of hydrophobic base F are prepared for screening. The interactions of plasma proteins with F-base-modified siRNA (F-siRNA) are investigated, and it is identified that the interaction with serum albumin is dominant. Experiments revealed that the introduction of F bases conferred modified siRNA with improved tumor-specific accumulation, prolonged circulatory retention time, and better tissue permeability. Mechanistic studies indicated that the F base induces the formulation of a stable siRNA-albumin complex, which transports siRNA to tumor tissues selectively owing to an enhanced permeability and retention (EPR) effect of albumin. The F base also facilitates the binding of siRNA to transport-associated proteins on the cell membrane, enabling its cellular internalization. Together, these data demonstrate that F base modification confers siRNA-enhanced cellular uptake and biostability and specific accumulation in tumor tissue, which provides a new approach for the development of siRNA-based cancer therapeutics.

Differences in Human Plasma Protein Interactions between Various Polymersomes and Stealth Liposomes as Observed by Fluorescence Correlation Spectroscopy.

A significant factor hindering the clinical translation of polymersomes as vesicular nanocarriers is the limited availability of comparative studies detailing their interaction with blood plasma proteins compared to liposomes. Here, polymersomes are self-assembled via film rehydration, solvent exchange, and polymerization-induced self-assembly using five different block copolymers. The hydrophilic blocks are composed of anti-fouling polymers, poly(ethylene glycol) (PEG) or poly(2-methyl-2-oxazoline) (PMOXA), and all the data is benchmarked to PEGylated "stealth" liposomes. High colloidal stability in human plasma (HP) is confirmed for all but two tested nanovesicles. In situ fluorescence correlation spectroscopy measurements are then performed after incubating unlabeled nanovesicles with fluorescently labeled HP or the specific labeled plasma proteins, human serum albumin, and clusterin (apolipoprotein J). The binding of HP to PMOXA-polymersomes could explain their relatively short circulation times found previously. In contrast, PEGylated liposomes also interact with HP but accumulate high levels of clusterin, providing them with their known prolonged circulation time. The absence of significant protein binding for most PEG-polymersomes indicates mechanistic differences in protein interactions and associated downstream effects, such as cell uptake and circulation time, compared to PEGylated liposomes. These are key observations for bringing polymersomes closer to clinical translation and highlighting the importance of such comparative studies.

Unravelling Binding of Human Serum Albumin with Galantamine: Spectroscopic, Calorimetric, and Computational Approaches.

Human serum albumin (HSA), an abundant plasma protein, binds to various ligands, acting as a transporter for numerous endogenous and exogenous substances. Galantamine (GAL), an alkaloid, treats cognitive decline in mild to moderate Alzheimer’s disease and other memory impairments. A vital step in pharmacological profiling involves the interaction of plasma protein with the drugs, and this serves as an essential platform for pharmaceutical industry advancements. This study is carried out to understand the binding mechanism of GAL with HSA using computational and experimental approaches. Molecular docking revealed that GAL preferentially occupies Sudlow’s site I, i.e., binds to subdomain IIIA. The results unveiled that GAL binding does not induce any conformational change in HSA and hence does not compromise the functionality of HSA. Molecular dynamics simulation (250 ns) deciphered the stability of the HSA–GAL complex. We performed the fluorescence binding and isothermal titration calorimetry (ITC) to analyze the actual binding of GAL with HSA. The results suggested that GAL binds to HSA with a significant binding affinity. ITC measurements also delineated thermodynamic parameters associated with the binding of GAL to HSA. Altogether, the present study deciphers the binding mechanism of GAL with HSA.

Altered Plasma Proteins in Myogenous Temporomandibular Disorders.

The aims of this study were (1) to compare the levels and interactions of several plasma proteins in patients with myogenous temporomandibular disorders (TMDM) compared to healthy and pain-free controls, (2) to compare the levels and interactions in two TMDM subgroups, myalgia (MYA) and myofascial pain (MFP), and (3) to explore associations between the proteins and clinical data. Thirty-nine patients with TMDM (MFP, n = 25, MYA, n = 14), diagnosed according to the diagnostic criteria for TMD (DC/TMD), aged 38 years, and sex-matched pain-free controls completed an extended DC/TMD Axis II questionnaire and the plasma concentration of 87 biomarkers were analyzed. Nine proteins separated TMDM from controls (p = 0.0174) and 12 proteins separated MYA from MFP (p = 0.019). Pain duration, characteristic pain intensity, pain catastrophizing, perceived stress, and insomnia severity were significantly associated with protein markers (p < 0.001 to p < 0.022). In conclusion, several plasma proteins were upregulated in TMDM and either upregulated or downregulated in MYA compared to MFP. Some proteins in TMDM were associated with pain variables, sleep disturbance, and emotional function. These results show that systemic differences in protein expression exist in patients with TMDM and that altered levels of specific plasma proteins are associated with different clinical variables.

Understanding the Role of Axial Ligands in Modulating the Biopharmaceutical Outcomes of Cisplatin(IV) Derivatives.

Cisplatin is a platinum (Pt)-based anticancer drug with broad-scale clinical utility. However, due to its hydrophilic nature and high kinetic reactivity, it offers numerous drug delivery challenges. Limitations such as severe systemic toxicities, chemoresistance, extensive cisplatin-plasma protein interaction, and limited cellular drug uptake reduce the therapeutic impact of cisplatin therapy. Cisplatin(IV) prodrug formation can effectively resolve these challenges. The selection of axial ligands could play a key role in determining the fate of cisplatin(IV) prodrugs by modulating the therapeutic and biopharmaceutical outcomes of therapy. Hereby, three cisplatin(IV) derivatives were developed utilizing valproate, tocopherol, and chlorambucil as axial ligands, and their biopharmaceutical performance was compared along with cisplatin. The impact of cisplatin(IV) derivative formation on their kinetic stability, drug-albumin interaction, cytotoxicity profile, cellular uptake pattern, self-assembling behavior, hemotoxicity, and tumor biodistribution pattern was analyzed to establish the correlation between the structural properties of cisplatin(IV) agents and their biopharmaceutical outcomes. The kinetic inertness of the designed cisplatin(IV) compounds helped in minimizing their plasma protein interactions and ensuring their stability in the blood environment. The lipophilicity enhancement due to Pt(IV) prodrug formation critically helped in enhancing the cellular drug uptake and reduced the dependence on transporters for drug uptake. The lipophilicity and activity of axial ligands were the key drivers governing the biopharmaceutical performance of the Pt(IV) derivatives. The properties of the axial ligand, such as its therapeutic activity, chemical backbone, and functional groups present in its structure, were the critical factors determining their plasma protein interaction, cellular uptake, anticancer activity, and self-assembly pattern. Cisplatin(IV) derivative formation further improved the amount of platinum accumulated in tumors after intravenous injection compared to free cisplatin therapy (2.7-5.4 folds increment) and reduced drug-erythrocyte interactions. Overall, the results highlighted the potential of cisplatin(IV) agents in resolving cisplatin drug delivery challenges and denoted the critical role of axial ligand selection in Pt(IV) prodrug designing.

Spectroscopic and Molecular Docking Investigation on the Interaction of Cumin Components with Plasma Protein: Assessment of the Comparative Interactions of Aldehyde and Alcohol with Human Serum Albumin.

The interaction of the important plasma protein, human serum albumin (HSA), with two monoterpenes found in cumin oil, i.e., cuminaldehyde (4-isopropylbenzaldehyde) and cuminol (4-isopropylbenzyl alcohol), was studied in this paper. Both experimental and computational methods were utilized to understand the mechanism of binding. The UV absorption profile of HSA changes in the presence of both cuminaldehyde and cuminol, due to the interaction between HSA with both monoterpenes. The intrinsic fluorescence intensity of HSA was also quenched on the sequential addition of both ligands, due to change in the microenvironment of the fluorophore present in the former. Quenching of HSA by cuminaldehyde was much higher in comparison to that in the presence of cuminol. Fluorescence quenching data were analyzed using modified Stern-Volmer and Lineweaver-Burk methods, which suggested that the binding mechanism was of a static type for both ligands. In both cases, the binding was favored by the domination of hydrophobic as well as hydrogen bonding/Van der Waals forces. Both ligands partially unfolded the secondary structure of HSA, although the effect of cuminaldehyde was more pronounced, as compared to cuminol. The preferred binding site of cuminaldehyde and cuminol inside HSA was also the same; namely, drug binding site 1, located in subdomain IIA. The study showed that cuminaldehyde binds strongly with albumin as compared to its alcohol counterpart, which is due to the more hydrophobic nature of the former.

Exploring the efficacy of ethylene glycol dimethacrylate crosslinked cationised pullulan for gene delivery in cancer cells

The balance between cytotoxicity and transfection efficiency is essential for any cationic polymers intended for gene delivery. However, increase in transfection efficiency of these cationic polymers is usually associated with an increase in the toxicity owing to the high positive surface charge. In this study pullulan was cationised with polyethyleneimine (pullulan-PEI) and was cross-linked with ethylene glycol dimethacrylate (EGDMA). Crosslinked pullulan –PEI (PPE) was found to be cytocompatible and formed nanoplexes of size of about 150 nm and 9.96 mV. The presence of EGDMA groups reduced the plasma protein interactions as well. The nanoplex uptake and transfection efficacy studies of PPE were done in C6 and HeLa cells. The interesting observation was that these nanoplexes exhibited differential uptake in these cell lines. The cellular uptake was very high in C6 glioma cells where as it was very low in HeLa and consequently gene expression was observed in the former cells only. Transfection efficacy of PPE derivatives was evaluated using p53 plasmid whose expression induces apoptosis in the cancerous cells. Immunostaining experiments and flow cytometry analysis following Annexin V staining confirmed the expression of p53 protein and apoptosis respectively in the PPEI/p53 poyplex transfected C6 cells.

Connecting Single Nucleotide Polymorphisms, Glycosylation Status and Interactions of Acute-Phase Plasma Proteins

Connecting Single Nucleotide Polymorphisms, Glycosylation Status and Interactions of Acute-Phase Plasma Proteins

Evaluation of europium-based carbon nanocomposites as bioimaging probes: Preparation, NMR relaxivities, binding effects over plasma proteins and cytotoxic aspects

It is highly desirable to develop water-dispersible lanthanide-based luminescent probes with facile preparation, great bioavailability, and excellent photo properties for biomedical applications. Numerous carbon photoactive nanostructures (from diverse sources) have been reported for broad applications as surfactants, pollutants degradation, metal sensing and in vitro/in vivo bioimaging applications. Here, europium-based carbon nanocomposites (EuCQD) have been synthesized and well-characterized by their magneto-optical and biophysical properties. The obtained EuCQD is small in size (≅ 5 nm), highly water dispersible and composed essentially of carbon, europium and oxygen. Furthermore, the obtained nanocomposite presents Eu/CQD hybrid luminescent properties and high NMR relaxivities. The impact on biological media has been investigated based on plasma protein interactions and cytotoxicity assays. The results reveal that EuCQDs bind firmly (Ka ≈ 104–105 M−1) to studied plasma proteins (BSA and HTF) mainly by Van der Waals interaction and hydrogen bonds. Furthermore, protein CD spectra reveal that both proteins experience structural changes during EuCQD interaction, and the nanocomposite presents very low toxicity against HBMEC, A549, and HTC116 cells. All the presented results expose EuCQD as an excellent alternative to other lanthanide probes for bi-functional bioimaging applications and open the prospect of turning it accessible for industrial production and clinical translation.

High voltage atmospheric cold plasma modification of bovine serum albumin

While atmospheric cold plasma has successfully inactivated biohazardous proteinaceous molecules (unwanted enzymes, prions, and allergens) and modified proteins with improved functionality, few studies have characterized plasma-protein interactions. This study investigates the physicochemical interactions, structural alteration, and reaction mechanisms of bovine serum albumin (BSA) subjected to high voltage atmospheric cold plasma (HVACP) generated by a dielectric barrier discharge in sealed bags packed with air or modified air (65% O2, 30% N2, 5% CO2). Treating 10 mL of BSA solution (50 mg/mL) with HVACP for 60 min changed the sample from transparent to yellow and induced protein precipitation. HVACP also induced protein unfolding, altered secondary structure (27% loss of α-helix), and increased disorder structure (10% increase of random coil). HVACP-treated protein increased in average size from 10 nm to 113 μm, with a broader size distribution after 60 min of HVACP treatment. SDS-PAGE and mass spectrometry showed the formation of new peptides from 1 to 10 kDa, indicating plasma-triggered peptide bond cleavage. Chemical analysis and mass spectrometry demonstrated oxidation and deamidation in HVACP-treated samples. This study illustrates that interactions between HVACP-induced reactive species and proteins may introduce structural alterations, protein aggregation, peptide cleavage, and side-group modifications to proteins in aqueous conditions.

Protection strategies for biocatalytic proteins under plasma treatment

In plasma-driven biocatalysis, enzymes are employed to carry out reactions using species generated by non-thermal plasmas as the precursors. We have previously demonstrated that this is feasible in principle, but that the approach suffers from the short lifetime of the biocatalyst under operating conditions. In this work, protection strategies were investigated to prevent the dielectric barrier discharge plasma-induced inactivation of biocatalysts, using recombinant unspecific peroxygenase from Agrocybe aegerita( rAaeUPO), one of the most promising enzymes for plasma-driven biocatalysis. Treatment in oxygen-free atmospheres did not provide any advantage over treatment in synthetic air, indicating that the detrimental reactive species did not originate from oxygen in the plasma phase. Chemical scavengers were employed to eliminate undesired reactive species, without any long-term effect on enzyme lifetime. Similarly, chaperones, including the known stress response proteins Hsp33, CnoX, and RidA did not increase the lifetime of rAaeUPO. Immobilization of the biocatalyst proved effective in preserving enzyme activity. The residual activity of rAaeUPO after plasma treatment strongly depended on the specific immobilization support. Essentially complete protection for at least 15 min of plasma exposure was achieved with an epoxy-butyl-functionalized carrier. This study presents new insights into plasma–protein interactions and plots a path forward for protecting biocatalytic proteins from plasma-mediated inactivation.

Localized Disruption of Blood Albumin–Phenytoin Binding Using Transcranial Focused Ultrasound

Plasma protein binding (PPB) plays an important role in drug pharmacokinetics, particularly for central nervous system drugs, as PPB affects the blood concentration of unbound drug available to cross the blood–brain barrier (BBB). We report the non-invasive, spatially specific disruption of PPB to phenytoin, an anti-epileptic drug with high affinity to albumin, using 250-kHz focused ultrasound (FUS) delivered in a pulsed manner (55-ms tone burst duration, 4-Hz pulse repetitions). Equilibrium dialysis performed on sonicated phosphate-buffered saline solution containing phenytoin and bovine serum albumin revealed a 27.7% elevation in the unbound phenytoin concentration compared with an unsonicated control. Sonication of a unilateral brain hemisphere in rats (n = 10) after intraperitoneal phenytoin injection revealed increased parenchymal phenytoin uptake compared with the unsonicated hemisphere, without evidence of temperature change or BBB disruption. These findings illustrate the use of FUS as a novel technique for spatially selective disruption of PPB, which may be applied to a wide range of drug–plasma protein interactions.

The Interaction of the Blood Plasma Proteins with Metal Oxide Nanoparticles (According to Light Scattering)

The Interaction of the Blood Plasma Proteins with Metal Oxide Nanoparticles (According to Light Scattering)

Protein corona fingerprinting to differentiate sepsis from non-infectious systemic inflammation.

Rapid and accurate diagnosis of sepsis remains clinically challenging. The lack of specific biomarkers that can differentiate sepsis from non-infectious systemic inflammatory diseases often leads to excessive antibiotic treatment. Novel diagnostic tests are urgently needed to rapidly and accurately diagnose sepsis and enable effective treatment. Despite investment in cutting-edge technologies available today, the discovery of disease-specific biomarkers in blood remains extremely difficult. The highly dynamic environment of plasma restricts access to vital diagnostic information that can be obtained by proteomic analysis. Here, we employed clinically used lipid-based nanoparticles (AmBisome®) as an enrichment platform to analyze the human plasma proteome in the setting of sepsis. We exploited the spontaneous interaction of plasma proteins with nanoparticles (NPs) once in contact, called the 'protein corona', to discover previously unknown disease-specific biomarkers for sepsis diagnosis. Plasma samples obtained from non-infectious acute systemic inflammation controls and sepsis patients were incubated ex vivo with AmBisome® liposomes, and the resultant protein coronas were thoroughly characterised and compared by mass spectrometry (MS)-based proteomics. Our results demonstrate that the proposed nanoparticle enrichment technology enabled the discovery of 67 potential biomarker proteins that could reproducibly differentiate non-infectious acute systemic inflammation from sepsis. This study provides proof-of-concept evidence that nanoscale-based 'omics' enrichment technologies have the potential to substantially improve plasma proteomics analysis and to uncover novel biomarkers in a challenging clinical setting.

Biological activity and photocatalytic properties of a naphthyl-imidazo phenanthroline (HNAIP) ligand and its [Ir(ppy)2(HNAIP)]Cl and [Rh(ppy)2(HNAIP)]Cl complexes

The synthesized 2-(hydroxy-1-naphtyl)imidazo-[4,5-f][1,10]phenanthroline (HNAIP) ligand and its new iridium ([Ir(ppy)2(HNAIP)]Cl) and rhodium ([Rh(ppy)2(HNAIP)]Cl) complexes, being ppy = 2-phenylpiridinate, show cytotoxic effects in SW480 (colon adenocarcinoma) and A549 (epithelial lung adenocarcinoma) cells. They all are cytotoxic in the tested cell lines. HNAIP and [Rh(ppy)2(HNAIP)]+ are the most cytotoxic, whereas [Ir(ppy)2(HNAIP)]+ displays negligible cytotoxicity towards A549 cells and moderate activity towards SW480. The interaction of all three compounds with Bovine Serum Albumin (BSA), l-glutathione reduced (GSH), nicotinamide adenine dinucleotide (NADH) and DNA was studied to explain the differences found in terms of cytotoxicity. None of them are able to interact with BSA, thus excluding bioavailability due to plasma protein interaction as the possible differentiating factor in their biological activity. By contrast, small differences have been observed regarding DNA interaction. In addition, taking advantage of the emission properties of these molecules, they have been visualized in the cytoplasmic region of A549 cells. Inductively coupled plasma mass spectrometry (ICP-MS) experiments show, in turn, that the internalization ability follow the sequence [Rh(ppy)2(HNAIP)]+ > [Ir(ppy)2(HNAIP)]+ > cisplatin. Therefore, it seems clear that the cellular uptake by tumour cells is the key factor affecting the different cytotoxicity of the metal complexes and that this cellular uptake is influenced by the hydrophobicity of the studied complexes. On the other hand, preliminary catalytic experiments performed on the photo-oxidation of GSH and some amino acids such as l-methionine (Met), l-cysteine (Cys) and l-tryptophan (Trp) provide evidence for the photocatalytic activity of the Ir(III) complex in this type of reactions.

Hybrid Tracers Based on Cyanine Backbones Targeting Prostate-Specific Membrane Antigen: Tuning Pharmacokinetic Properties and Exploring Dye-Protein Interaction.

Prostate cancer surgery is currently being revolutionized by the use of prostate-specific membrane antigen (PSMA)-targeted radiotracers, for example, 99mTc-labeled PSMA tracer analogs for radioguided surgery. The purpose of this study was to develop a second-generation 99mTc-labeled PSMA-targeted tracer incorporating a fluorescent dye. Methods: Several PSMA-targeted hybrid tracers were synthesized: glutamic acid-urea-lysine (EuK)-Cy5-mas3, EuK-(SO3)Cy5-mas3, EuK-Cy5(SO3)-mas3, EuK-(Ar)Cy5-mas3, and EuK-Cy5(Ar)-mas3; the Cy5 dye acts as a functional backbone between the EuK targeting vector and the 2-mercaptoacetyl-seryl-seryl-seryl (mas3) chelate to study the dye's interaction with PSMA's amphipathic entrance funnel. The compounds were evaluated for their photophysical and chemical properties and PSMA affinity. After radiolabeling with 99mTc, we performed in vivo SPECT imaging, biodistribution, and fluorescence imaging on BALB/c nude mice with orthotopically transplanted PC346C tumors. Results: The dye composition influenced the photophysical properties (brightness range 0.3-1.5 × 104 M-1 × cm-1), plasma protein interactions (range 85.0% ± 2.3%-90.7% ± 1.3% bound to serum, range 76% ± 0%-89% ± 6% stability in serum), PSMA affinity (half-maximal inhibitory concentration [IC50] range 19.2 ± 5.8-175.3 ± 61.1 nM) and in vivo characteristics (tumor-to-prostate and tumor-to-muscle ratios range 0.02 ± 0.00-154.73 ± 28.48 and 0.46 ± 0.28-5,157.50 ± 949.17, respectively; renal, splenic, and salivary retention). Even though all tracer analogs allowed tumor identification with SPECT and fluorescence imaging, 99mTc-EuK-(SO3)Cy5-mas3 had the most promising properties (e.g., half-maximal inhibitory concentration, 19.2 ± 5.8, tumor-to-muscle ratio, 5,157.50 ± 949.17). Conclusion: Our findings demonstrate the intrinsic integration of a fluorophore in the pharmacophore in PSMA-targeted small-molecule tracers. In this design, having 1 sulfonate on the indole moiety adjacent to EuK (99mTc-EuK-(SO3)Cy5-mas3) yielded the most promising tracer candidate for imaging of PSMA.