intranasal delivery 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.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Before the 17th century, medical practitioners poured hot oil into wounds in order to cauterize damaged blood vessels, but the French surgeon Ambroise Paré challenged the use of this method in 1545. Paré was the first to propose controlling bleeding using ligature. During the American Civil War, chloroform was used during surgery to reduce pain and allow more time for operations. Due in part to the lack of sterile technique in hospitals, infection was the leading cause of death for wounded soldiers. In World War I, doctors began replacing patients' lost fluid with salt solutions. With World War II came the idea of blood banking, having quantities of donated blood available to replace lost fluids. The use of antibiotics also came into practice in World War II.
=== Polished === Mirror polished stainless-steel belts to produce several types of thin film and ceramic sheets. The belts are available in thickness from 0.60 to 2.00 mm (0.02362 to 0.0787 in.) with thickness variation less than or equal to 80 μm. Polished steel belts are produced endlessly or as open-length belts.
Proteins are classified into the chemokine family based on their structural characteristics, not just their ability to attract cells. All chemokines are small, with a molecular mass of between 8 and 10 kDa, optimally designed to ensure efficient communications. They are approximately 20-50% identical to each other; that is, they share gene sequence and amino acid sequence homology. They all also possess conserved amino acids that are important for creating their 3-dimensional or tertiary structure, such as (in most cases) four cysteines that interact with each other in pairs to create a Greek key shape that is a characteristic of chemokines. Intramolecular disulfide bonds typically join the first to third, and the second to fourth cysteine residues, numbered as they appear in the protein sequence of the chemokine. Typical chemokine proteins are produced as pro-peptides, beginning with a signal peptide of approximately 20 amino acids that gets cleaved from the active (mature) portion of the molecule during the process of its secretion from the cell. The first two cysteines, in a chemokine, are situated close together near the N-terminal end of the mature protein, with the third cysteine residing in the centre of the molecule and the fourth close to the C-terminal end. A loop of approximately ten amino acids follows the first two cysteines and is known as the N-loop. This is followed by a single-turn helix, called a 310-helix, three β-strands and a C-terminal α-helix.
Naturally occurring zirconium (40Zr) is composed of four stable isotopes (one, 94Zr, may in the future be found radioactive), and one very long-lived radioisotope (96Zr), a primordial nuclide that decays via double beta decay with an observed partial half-life of 2.34 × 1019 years; it can also undergo single beta decay, with a partial half-life of [2.27+0.53−0.36 (stat) ± 0.27 (syst)] × 1020 years. The second most stable radioisotope is 93Zr, which has a half-life of 1.61 million years. Thirty other radioisotopes have been observed from 77Zr to 114Zr; all have half-lives less than a day except for 95Zr (64.032 days), 88Zr (83.4 days), and 89Zr (78.36 hours). The most stable of the isomeric states is just 4.16 minutes for 89mZr. Radioactive isotopes above the theoretically stable mass numbers 90–92 decay by electron emission resulting in niobium isotopes, whereas those below by positron emission or electron capture, resulting in yttrium isotopes.
Sources: en.wikipedia.org
In October 2008, Russian journalist Irina Kuksenkova wrote in Moskovskij Komsomolets, "Russia fought in Ossetia for the strategically important territory. Now, even if NATO arrives in Georgia, we will have military bases in Java and Tskhinvali. This explains the fact that for 15 hours since the beginning of the war, our people did not undertake any action as if luring in Georgians, so then there would be something to present to the international community." In October 2008, Andrey Illarionov, former advisor to Vladimir Putin, in his interview with Echo of Moscow declared that it was suspicious that the evacuation of almost entire South Ossetian population began on 2 August and was finished before 8 August 2008, because this had not happened before during the previous escalations of tensions in the past 20 years. After the evacuation of the civilian population, the mobilization of volunteers started in the North Caucasus. Illarionov stated that the war is started with the mobilization. On 3 August 2008, the volunteers started to arrive in South Ossetia. Illarionov noted that all the volunteers were registered in the Military commissariats of the North Caucasus republics and were organized. On 4 August, several Russian special forces were deployed in South Ossetia. Illarionov also noted that since the late July the Ossetian media was reporting that the war was imminent and that Russian 58th Army would help them.
It is sometimes said that validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?". "Building the right thing" refers back to the user's needs, while "building it right" checks that the specifications are correctly implemented by the system. In some contexts, it is required to have written requirements for both as well as formal procedures or protocols for determining compliance. It is entirely possible that a product passes when verified but fails when validated. This can happen when, say, a product is built as per the specifications but the specifications themselves fail to address the user's needs.
=== Neutrons === After the discovery of the neutron by James Chadwick in 1932, the ultimate root cause for the existence of isotopes was clarified, that is, the nuclei of different isotopes for a given element have different numbers of neutrons, albeit having the same number of protons.
==== UPS European service hub ==== UPS' European service hub is located at Cologne Bonn Airport in Cologne, Germany. The Cologne Hub handles 190,000 packages an hour in the 57,000m² facility. It is the second-busiest UPS hub worldwide, in terms of daily flights serving more than 200 countries and territories around the world.
In more recent years, CT scanning has become an invaluable tool in the study of mummification by allowing researchers to digitally "unwrap" mummies without risking damage to the body. The level of detail in such scans is so intricate that small linens used in tiny areas such as the nostrils can be digitally reconstructed in 3-D. Such modelling has been utilized to perform digital autopsies on mummies to determine the cause of death and lifestyle, such as in the case of Tutankhamun.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.