Lyophilisation is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-02-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Stereoselective activation: Stereoselective activation of (R)-profen by the formation of the thioester, in the presence of CoA, ATP and Mg+2. (S)-profen does not form the thioester. Epimerization (Racemization): The enzyme epimerase 2-arylpropionic-CoA changes the (R)-thioester to the (S)-thioester. This process is called "racemization" or "epimerization." Hydrolysis: With the help of hydrolase/thioesterase, thioesters are broken down into their (R)- and (S)-forms Because the acyl-CoA thioester (profenyl-CoA) changes the structure of triglycerides and phospholipids, metabolic chiral inversion may cause toxic effects.
=== Tendon treatment === Several studies have shown a correlation between the administration of bone growth factors and the amelioration of the tendon-to-bone healing. The focus of these studies was primarily on the anterior cruciate ligament (ACL) located in the knee, due to the high number of injuries sustained by athletes. The University of Dammam, King Fahd Hospital in Saudi Arabia was able to show that the addition of SHMSP bone growth factor via powder facilitated the process of tendon-graft healing in rabbits. Comparison of this SHMSP test group to the control group illustrated a higher level of formation and organization within the knee. The Hospital for Special Surgery in New York conducted a similar study, in which a collagen sponge containing bone protein was implanted in the ACL of rabbits. In this case, the bone protein isolated from bovine femurs contained several bone morphogenetic proteins, which are part of an important signaling system that aides in the structure of bones. As with the application of SHMSP, the inclusion of bone protein in the collagen sponge was seen to improve the healing process, when compared to control groups with the sponge alone or no sponge. In a separate study also implemented by the Hospital for Special Surgery as well as the University of California, treatment of the anterior cruciate ligament utilized the recombinant human bone morphogenic protein rhBMP-2 in two phases.
According to the National Drug Intelligence Center, Mexican cartels are the predominant smugglers and wholesale distributors of South American cocaine and Mexico-produced cannabis, methamphetamine, and heroin. The U.S. State Department estimates that 90 percent of cocaine entering the United States is produced in Colombia, followed by Bolivia and Peru, and that the main transit route is through Mexico. Mexican cartels control large swaths of territory, and most of the illegal drugs coming into the U.S., employing land routes, maritime shipments, smuggling tunnels, and other concealment methods. Cartels have waged violent turf battles over control of key smuggling corridors from Matamoros to Tijuana. Cartels operate clandestine laboratories that process precursor chemicals into synthetic drugs. These chemicals are primarily imported from Asia, especially China and India, and are used to manufacture methamphetamine and fentanyl in large quantities. Since the 2010s, fentanyl has become one of the most profitable components of cartel operations due to its low production cost and high potency. Although Mexico accounts for only a small share of worldwide heroin production, it supplies a large share of the heroin distributed in the United States. Since the 2000s, Mexican cartels have profited from marijuana cultivation in remote U.S. forests. A 2018 study found that the reduction in drugs from Colombia contributed to Mexican drug violence.
== Analysis == A wide range of instrumental techniques are employed in nuclear forensics. Radiometric counting techniques are useful when determining decay products of species with short half-lives. However, for longer half-lives, inorganic mass spec is a powerful means of carrying out elemental analysis and determining isotopic relationships. Microscopy approaches can also be useful in characterization of a nuclear material.
Sources: en.wikipedia.org
=== Structural analysis software === NASA software engineers have created thousands of computer programs over the decades equipped to design, test, and analyze stress, vibration, and acoustical properties of a broad assortment of aerospace parts and structures. The NASA Structural Analysis Program, or NASTRAN, is considered one of the most successful and widely used NASA software programs. It has been used to design everything from Cadillacs to roller coaster rides. Originally created for spacecraft design, it has been employed in a host of non-aerospace applications and is available to industry through NASA's Computer Software Management and Information Center (COSMIC). COSMIC maintains a library of computer programs from NASA and other government agencies and sells them at a fraction of the cost of developing a new program. NASA Structural Analysis Computer Software was inducted into the Space Foundation Space Technology Hall of Fame in 1988.
The Netherlands is the world's main producer of commercial tulip plants, producing as many as 3 billion bulbs annually, the majority for export. "Unlike many flower species, tulips do not produce nectar to entice insect pollination. Instead, tulips rely on wind and land animals to move their pollen between reproductive organs. Because they are self-pollinating, they do not need the pollen to move several feet to another plant but only within their blossoms." Tulips can be propagated through bulb offsets, seeds or micropropagation. Offsets and tissue culture methods are means of asexual propagation for producing genetic clones of the parent plant, which maintains cultivar genetic integrity. Seeds are most often used to propagate species and subspecies or to create new hybrids. Many tulip species can cross-pollinate with each other, and when wild tulip populations overlap geographically with other tulip species or subspecies, they often hybridise and create mixed populations. Most commercial tulip cultivars are complex hybrids, and often sterile. Offsets require a year or more of growth before plants are large enough to flower. Tulips grown from seeds often need five to eight years before plants are of flowering size. To prevent cross-pollination, increase the growth rate of bulbs and increase the vigour and size of offsets, the flower and stems of a field of commercial tulips are usually topped using large tractor-mounted mowing heads. The same goals can be achieved by a private gardener by clipping the stem and flower of an individual specimen.
==== Fear and anxiety ==== Oxytocin is typically remembered for its effects on prosocial behaviors, such as its role in facilitating trust and attachment between individuals. However, oxytocin has a more complex role than solely enhancing prosocial behaviors. There is consensus that oxytocin modulates fear and anxiety; that is, it does not directly elicit fear or anxiety. Two dominant theories explain the role of oxytocin in fear and anxiety. One theory states that oxytocin increases approach/avoidance to certain social stimuli, and the second theory states that oxytocin increases the salience of certain social stimuli, causing animals (including humans) to pay closer attention to socially relevant stimuli. Nasally administered oxytocin has been reported to reduce fear, possibly by inhibiting the amygdala (which is thought to be responsible for fear responses). Indeed, studies in rodents have shown oxytocin can efficiently inhibit fear responses by activating an inhibitory circuit within the amygdala. Some researchers have argued oxytocin has a general enhancing effect on all social emotions, since intranasal administration of oxytocin also increases envy and Schadenfreude. Individuals who receive an intranasal dose of oxytocin identify facial expressions of disgust more quickly than individuals who do not receive oxytocin. Facial expressions of disgust are evolutionarily linked to the idea of contagion. Thus, oxytocin increases the salience of cues that imply contamination, which leads to a faster response because these cues are especially relevant for survival.
Most magnetic nanoparticle applications in clinical settings are used for cancer therapies. Magnetic nanoparticles have the ability to target the specific locus of the tumor, use a decreased amount of drug to treat the tumor, and result in decreased off-target effects of the drug. The most common method of introducing magnetic nanoparticles into the body is through intravenous injection; from the site of injection, the nanoparticles travel through the bloodstream. They eventually migrate to the target site with the use of external or implanted magnetic forces. A pH/magnetic field dual responsive drug loaded nanomicell was developed for targeted magnetothermal synergistic chemotherapy of cancer. In this drug delivery system, after the drug reaches the target site and tumor cell uptake is complete, an external magnetic field is applied causing a magnetothermal effect, raising the tumor cells' temperature and further promoting drug uptake. This nanocarrier system aims to improve drug stability, control drug release, and improve tumor targeting efficacy. This approach has shown increased treatment efficacy over traditional chemotherapy and has not demonstrated any noticeable biotoxicity. Cardiovascular disease treatment presents as another application of magnetic nanoparticle drug delivery. Atherosclerosis cardiovascular disease is a buildup of plaque in the inner lining of the arteries, and there are models on how magnetic nanoparticle drug delivery could be used as a treatment.
Selected-ion flow-tube mass spectrometry (SIFT-MS) is a quantitative mass spectrometry technique for trace gas analysis which involves the chemical ionization of trace volatile compounds by selected positive precursor ions during a well-defined time period along a flow tube. Absolute concentrations of trace compounds present in air, breath or the headspace of bottled liquid samples can be calculated in real time from the ratio of the precursor and product ion signal ratios, without the need for sample preparation or calibration with standard mixtures. The detection limit of commercially available SIFT-MS instruments extends to the single digit pptv range. The instrument is an extension of the selected ion flow tube, SIFT, technique, which was first described in 1976 by Adams and Smith. It is a fast flow tube/ion swarm method to react positive or negative ions with atoms and molecules under truly thermalised conditions over a wide range of temperatures. It has been used extensively to study ion-molecule reaction kinetics. Its application to ionospheric and interstellar ion chemistry over a 20-year period has been crucial to the advancement and understanding of these topics. SIFT-MS was initially developed for use in human breath analysis, and has shown great promise as a non-invasive tool for physiological monitoring and disease diagnosis. It has since shown potential for use across a wide variety of fields, particularly in the life sciences, such as agriculture and animal husbandry, environmental research and food technology.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.