Factors controlling the size of proteinoid microspheres

Serotonergic Mechanisms in Proteinoid-Based Protocells

This study examines the effects of incorporating serotonin (5-HT) into proteinoid microspheres. It looks at the microspheres' structure and electrochemical properties. Proteinoid-serotonin assemblies have better symmetry and membrane organization than pristine proteinoids. Cyclic voltammetry shows a big boost in electron transfer. This is proven by a smaller peak separation and higher electrochemical efficiency. SEM imaging shows a distinct core-shell structure and uniform density. This suggests ordered molecular assembly. These findings show that serotonin changes proteinoid self-assembly. It creates structured systems with better electron transfer pathways. The serotonin-modified proto-neurons show new properties. They give insights into early cellular organization and signaling. This helps us understand prebiotic information processing systems.

Recurrence Resonance and 1/f Noise in Neurons Under Quantum Conditions and Their Manifestations in Proteinoid Microspheres

Recurrence resonance (RR), in which external noise is utilized to enhance the behaviour of hidden attractors in a system, is a phenomenon often observed in biological systems and is expected to adjust between chaos and order to increase computational power. It is known that connections of neurons that are relatively dense make it possible to achieve RR and can be measured by global mutual information. Here, we used a Boltzmann machine to investigate how the manifestation of RR changes when the connection pattern between neurons is changed. When the connection strength pattern between neurons forms a partially sparse cluster structure revealing Boolean algebra or Quantum logic, an increase in mutual information and the formation of a maximum value are observed not only in the entire network but also in the subsystems of the network, making recurrence resonance detectable. It is also found that in a clustered connection distribution, the state time series of a single neuron shows 1/f noise. In proteinoid microspheres, clusters of amino acid compounds, the time series of localized potential changes emit pulses like neurons and transmit and receive information. Indeed, it is found that these also exhibit 1/f noise, and the results here also suggest RR.

Towards proteinoid computers. Hypothesis paper

Proteinoids - thermal proteins - are produced by heating amino acids to their melting point and initiation of polymerisation to produce polymeric chains. Proteinoids swell in aqueous solution into hollow microspheres. The proteinoid microspheres produce endogenous burst of electrical potential spikes and change patterns of their electrical activity in response to illumination. The microspheres can interconnect by pores and tubes and form networks with a programmable growth. We speculate on how ensembles of the proteinoid microspheres can be developed into unconventional computing devices.

Engineering and use of proteinoid polymers and nanocapsules containing agrochemicals

To address global challenges such as population growth and climate change, introduction of new technologies and innovations in agriculture are paramount. Polymer-based formulations of agrochemicals have received much attention in recent years, and there is strong motivation to develop agrochemicals that are not harmful to the environment. Proteinoid polymers are produced by thermal step-growth polymerization of natural and unnatural amino acids. Under suitable gentle conditions, the proteinoid polymers may self-assemble to form nano-sized hollow proteinoid nanoparticles (NPs) of a relatively narrow size distribution. Agrochemical molecules may be encapsulated within these hollow proteinoid NPs, integrated in the crude proteinoid shell, or bound covalently/physically to the NP surface. In the present manuscript we prepared and characterized four model proteinoid polymers and NPs: P(KEf), P(KF), P(EWH-PLLA) and P(KWH-PLLA), where Ef denotes the unnatural herbicidal amino acid glufosinate. The NPs were fluorescently labeled and loaded with agrochemicals such as the plant hormone auxin. In addition, the NP surface was hydrophobized by covalent conjugation of dodecyl aldehyde via its surface primary amine groups. Following treatment of the plants with the different fluorescent-labeled NPs, fluorescent microscopic techniques enabled to localize the NPs and observe the accumulation in the plant's vascular system. Next, using genetically modified plants, which express fluorescent protein and are responsive to the level of auxin, we demonstrated the possibility to deliver encapsulated agrochemicals into cells. We also illustrated that the proteinoid NPs are non-toxic to human umbilical vein endothelial cells, and apart from P(KEf) also to lettuce plants.

Amino Acid Oligomer Microspheres as Drug Delivery Systems. II. Oligomerization of NCAs Initiated with L-Tyrosine Methyl Ester

Oligomerizations of various amino acid N-carboxyanhydrides (NCAs) were prepared in the presence of L-tyrosine methyl ester (Tyr.Me). Tyr.Me was found to be an efficient initiator to form oligopeptides consisting of L-aspartic acid, L-glutamic acid, L-phenylalanine, and L-tyrosine with random arrangements of amino acids. In acidic solution, the oligopeptides formed microspheres which were capable of encapsulating macromolecular drugs such as insulin and heparin. These microspheres were considered to be potential oral drug delivery systems.

Amino Acid Oligomer Microspheres as Drug Delivery Systems. I. Synthesis of Oligo(Amino Acids) via NCAs and Their Microsphere Formation

Some thermally derived proteinoids are known to form hollow microspheres under specific conditions. In this study, oligomers consisting of L-aspartic acid, L-glutamic acid, L-phenylalanine, and L-tyrosine were prepared through the corresponding a-amino acid-N carboxyanhydrides (NCAs). The oligo(amino acids) synthesized by NCA method had better control on the composition as well as molecular weight. These oligo(amino acids) were found to spontaneously form microspheres under acidic conditions. It was also found that is possible to encapsulate a variety of drug entities within these unique self-assembling systems. The microspheres which form spontaneously at low pH's also dissolve in water at neutral pH and consequently have the potential to be used as oral drug delivery systems.

Synthesis and characterization of bioactive conjugated near-infrared fluorescent proteinoid-poly(L-lactic acid) hollow nanoparticles for optical detection of colon cancer

Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with colon cancer. Near-infrared (NIR) fluorescent nanoparticles are promising candidates for use as contrast agents for tumor detection. Using NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum: lower autofluorescence of biological tissues and lower absorbance and, consequently, deeper penetration into biomatrices. The present study describes the preparation of new NIR fluorescent proteinoid-poly(L-lactic acid) (PLLA) nanoparticles. For this purpose, a P(EF-PLLA) random copolymer was prepared by thermal copolymerization of L-glutamic acid (E) with L-phenylalanine (F) and PLLA. Under suitable conditions, this proteinoid-PLLA copolymer can self-assemble to nanosized hollow particles of relatively narrow size distribution. This self-assembly process was used for encapsulation of the NIR dye indocyanine green. The encapsulation process increases significantly the photostability of the dye. These NIR fluorescent nanoparticles were found to be stable and nontoxic. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline containing 4% human serum albumin was not detected. Tumor-targeting ligands such as peanut agglutinin and anticarcinoembryonic antigen antibodies were covalently conjugated to the surface of the NIR fluorescent P(EF-PLLA) nanoparticles, thereby increasing the fluorescent signal of tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent P(EF-PLLA) nanoparticles was demonstrated in a chicken embryo model. In future work, we plan to extend this study to a mouse model, as well as to encapsulate a cancer drug such as doxorubicin within these nanoparticles for therapeutic applications.

Engineering of near infrared fluorescent proteinoid-poly(L-lactic acid) particles for in vivo colon cancer detection

Background

The use of near-infrared (NIR) fluorescence imaging techniques has gained great interest for early detection of cancer owing to the negligible absorption and autofluorescence of water and other intrinsic biomolecules in this region. The main aim of the present study is to synthesize and characterize novel NIR fluorescent nanoparticles based on proteinoid and PLLA for early detection of colon tumors.

Methods

The present study describes the synthesis of new proteinoid-PLLA copolymer and the preparation of NIR fluorescent nanoparticles for use in diagnostic detection of colon cancer. These fluorescent nanoparticles were prepared by a self-assembly process in the presence of the NIR dye indocyanine green (ICG), a FDA-approved NIR fluorescent dye. Anti-carcinoembryonic antigen antibody (anti-CEA), a specific tumor targeting ligand, was covalently conjugated to the P(EF-PLLA) nanoparticles through the surface carboxylate groups using the carbodiimide activation method.

Results and discussion

The P(EF-PLLA) nanoparticles are stable in different conditions, no leakage of the encapsulated dye into PBS containing 4% HSA was detected. The encapsulation of the NIR fluorescent dye within the P(EF-PLLA) nanoparticles improves significantly the photostability of the dye. The fluorescent nanoparticles are non-toxic, and the biodistribution study in a mouse model showed they evacuate from the body over 24 h. Specific colon tumor detection in a chicken embryo model and a mouse model was demonstrated for anti-CEA-conjugated NIR fluorescent P(EF-PLLA) nanoparticles.

Conclusions

The results of this study suggest a significant advantage of NIR fluorescence imaging using NIR fluorescent P(EF-PLLA) nanoparticles over colonoscopy. In future work we plan to broaden this study by encapsulating cancer drugs such as paclitaxel and/or doxorubicin, within these biodegradable NIR fluorescent P(EF-PLLA) nanoparticles, for both detection and therapy of colon cancer.

Enhanced catalytic activity from proteinoid microspheres

Creating materials that are capable of catalyzing enzymatic reactions could be important to the treatment of both acute and chronic wounds, as well as other topical diseases. As a first step in the design of catalytic biomaterials, a new class of proteinoid microsphere (PM), that includes amino acids found in phosphatase enzyme active sites, has been constructed. This material can significantly enhance catalytic activity for phosphoester hydrolysis, with observed specific activity increases between 35- and 55-fold. Further specific activity increases occur when metal cations, notably iron or zinc, are added to the PMs. Specific activity increases between 140- and 300-fold for these metal modified systems are measured. The phosphatase activity increase is demonstrated for both aromatic phosphate esters as well as the high-energy phosphate bond of adenosine triphosphate. PMs bind substrate heterogeneously on their surfaces in an enthalpically driven reaction that is defined by an overall favorable free energy, but unfavorable entropy. The catalytic PMs have been successfully blended with polyolefin foam and extruded with PLA. These materials remain fully active.

Triggered release from peptide-proteinoid microspheres

Proteinoid microspheres (PM) are unusual polymers formed by the thermal condensation of amino acids. Although they have been studied for over 60 years, they are only now beginning to garner interest as controlled release agents. Although they are very biocompatible, it has been problematic to design useful triggers that release small molecules from PM interiors. This has severely limited their usefulness. In the present study, short peptides have been successfully incorporated into PMs during their formation. The resulting hybrid peptide-PMs can release their interior content when hydrolyzed by a proteinase. Specifically, if a matrix metalloproteinase (MMP) cleavage site peptide is incorporated into a PM, the peptide-PM will release interior contents only in the presence of the MMP recognizing the cleavage peptide. The release rate can be determined by the concentration of the peptide in the PM synthesis mixture. This potentially makes peptide-PMs useful for delivering inhibitors or drugs into acute and chronic wounds, periodontal disease sites, and other disease states involving the fine-tuned regulation of proteinases.

Triggered release of small molecules from proteinoid microspheres

Proteinoid microspheres (PM) are formed by the thermal condensation of amino acids. They have been useful to further evolutionary theory, as catalysts for some biochemical reactions, but they have not been overly useful as controlled delivery agents. It is possible however to construct PMs that contain organic small molecules in the interior space. This means that a PM could be used as a delivery agent, if a suitable method could be discovered to cause the release of the internal material. This report describes the formation of a PM that includes a molecular bridging agent that can be removed in a reducing environment. Removal of the bridge opens a hole or window in the PM that allows the interior material to escape. The rate at which the interior material is released from the PM can be controlled by the size of the window or by the reduction potential in the environment. These PMs can be used to temporally treat a variety of complications including wounds (chronic or acute) by delivering a sequestered reagent in a controlled manner and are advantageous in that amino acids are the primary delivery vehicle breakdown product.