This is a working overview of lyophilization, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-13. Anything still debated is marked as such rather than presented as settled.
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
A freeze-dryer consists of a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. Vials, ampoules, or bulk trays hold the product during the cycle. The condenser traps water vapor as ice at a temperature lower than the product. Cycle development balances shelf temperature, chamber pressure, and time. Scale-up can be difficult because heat and mass transfer change with equipment size, so process analytical tools and conservative validation are often used.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | freeze-drying, lyophilisation, cryodesiccation | Lyophilization is common in pharmaceutical literature. |
| Typical chamber pressure during primary drying | 0.05–0.5 mbar (5–50 Pa) | Must remain below the triple point of water. |
| Typical shelf temperature during freezing | −40 to −20 °C | Lower temperatures may be used for eutectic systems. |
| Typical residual moisture after secondary drying | 0.5–3% w/w | Product-dependent; low moisture improves stability but can cause over-drying. |
| Typical analytical method for residual moisture | Karl Fischer titration or loss on drying | Thermogravimetric methods are also used. |
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
Equipment for lyophilization includes a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. A refrigeration system cools the shelves and condenser below the product's freezing point. Process monitoring often uses Pirani and capacitance manometers, thermocouples, and resistance sensors. Cycle development balances product quality with time and energy use. Some products are annealed during freezing to improve crystallization of bulking agents. Open questions remain about scaling cycles between laboratory, pilot, and production freeze-dryers.
Lyophilization, also called freeze-drying, removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts free water into ice and may also produce a glassy phase. Primary drying then lowers chamber pressure so ice sublimes directly to vapor without passing through a liquid stage. Secondary drying raises the temperature modestly to remove bound water. The result is a porous, dry solid that usually reconstitutes quickly. Each stage influences pore structure, residual moisture, and stability.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
=== SPAC merger, public listing, and acquisitions (2020–2023) === In October 2020, Hims announced an agreement to become a publicly traded company through a merger with Oaktree Acquisition Corp., a special-purpose acquisition company led by Oaktree Capital Management co-chairman Howard Marks. The transaction closed on January 20, 2021 at a valuation of $1.6 billion, and shares began trading the following day on the New York Stock Exchange. The deal provided the company with about $280 million in proceeds, including $75 million from private placement investors such as Franklin Templeton Investments. In June 2021, Hims & Hers acquired London-based Honest Health Limited, marking its first international acquisition and expanding its United Kingdom operations. The following month, the company acquired the teledermatology platform Apostrophe (YoDerm, Inc.) for potential consideration of up to $200 million. Apostrophe was shut down in 2025.
Many substances regarded as poisons are toxic only indirectly, by toxication. An example is "wood alcohol" or methanol, which is not poisonous itself, but is chemically converted to toxic formaldehyde and formic acid in the liver. Many drug molecules are made toxic in the liver, and the genetic variability of certain liver enzymes makes the toxicity of many compounds differ between individuals. Exposure to radioactive substances can produce radiation poisoning, an unrelated phenomenon. Two common cases of acute natural poisoning are theobromine poisoning of dogs and cats, and mushroom poisoning in humans. Dogs and cats are not natural herbivores, but a chemical defense developed by Theobroma cacao can be incidentally fatal nevertheless. Many omnivores, including humans, readily consume edible fungi, and thus many fungi have evolved to become decisively inedible, in this case as a direct defense.
The Tsitsin Main Botanical Garden of Academy of Sciences, founded in 1945, is the largest in Europe. This garden covers 3.61 square kilometers (1.39 sq mi) next to the All-Russia Exhibition Center; it contains a live exhibition of more than 20,000 species of plants from around the world, as well as a lab for scientific research. The garden contains a rosarium (with 20,000 rose bushes), a dendrarium, and an oak forest (whose average tree age exceeds 100 years). In addition, the garden contains a greenhouse occupying more than 5,000 square meters (53,820 square feet). The All-Russian Exhibition Center (Russian: Всероссийский выставочный центр) was formerly known as the All-Union Agricultural Exhibition (VSKhV) and later the Exhibition of Achievements of the National Economy (VDNKh), though it was officially called a "permanent trade show". This center is a prominent example of Stalinist-era monumental architecture. In this large recreational park, there are scores of pavilions, each representing one of two things: a branch of Soviet industry and science, or a Soviet republic. During the 1990s, the center was—and to some extent still is—misused as a shopping center. (Most pavilions are rented to small businesses.) Nevertheless, the center retains most of its architectural landmarks, including two monumental fountains (Stone Flower and Friendship of Nations) and a 360-degree panoramic cinema. In 2014, the park reverted to the name Exhibition of Achievements of National Economy; that same year, a large renovation project was started.
==== Thioredoxin and glutathione systems ==== The thioredoxin system contains the 12 kDa protein thioredoxin and its companion thioredoxin reductase. Proteins related to thioredoxin are present in all sequenced organisms. Plants, such as Arabidopsis thaliana, have a particularly great diversity of isoforms. The active site of thioredoxin consists of two neighboring cysteines, as part of a highly conserved CXXC motif, that can cycle between an active dithiol form (reduced) and an oxidized disulfide form. In its active state, thioredoxin acts as an efficient reducing agent, scavenging ROS and maintaining other proteins in their reduced state. After being oxidized, the active thioredoxin is regenerated by the action of thioredoxin reductase, using NADPH as an electron donor. The glutathione system includes glutathione, glutathione reductase, glutathione peroxidases, and glutathione S-transferases. This system is found in animals, plants and microorganisms. Glutathione peroxidase is an enzyme containing four selenium-cofactors that catalyzes the breakdown of hydrogen peroxide and organic hydroperoxides. There are at least four different glutathione peroxidase isozymes in animals. Glutathione peroxidase 1 is the most abundant and is a very efficient scavenger of hydrogen peroxide, while glutathione peroxidase 4 is most active with lipid hydroperoxides. Surprisingly, glutathione peroxidase 1 is dispensable, as mice lacking this enzyme have normal lifespans, but they are hypersensitive to induced oxidative stress.
==== MeSH E05.196.867 – spectrum analysis ==== MeSH E05.196.867.151 – circular dichroism MeSH E05.196.867.519 – magnetic resonance spectroscopy MeSH E05.196.867.519.274 – electron spin resonance spectroscopy MeSH E05.196.867.519.550 – nuclear magnetic resonance, biomolecular MeSH E05.196.867.576 – optical rotatory dispersion MeSH E05.196.867.660 – pulse radiolysis MeSH E05.196.867.726 – spectrometry, fluorescence MeSH E05.196.867.776 – spectrometry, gamma MeSH E05.196.867.776.751 – spectroscopy, mossbauer MeSH E05.196.867.800 – spectrometry, x-ray emission MeSH E05.196.867.800.360 – electron probe microanalysis MeSH E05.196.867.826 – spectrophotometry MeSH E05.196.867.826.300 – microspectrophotometry MeSH E05.196.867.826.551 – spectrophotometry, atomic MeSH E05.196.867.826.676 – spectrophotometry, infrared MeSH E05.196.867.826.676.700 – spectroscopy, fourier transform infrared MeSH E05.196.867.826.802 – spectrophotometry, ultraviolet MeSH E05.196.867.838 – spectroscopy, electron energy-loss MeSH E05.196.867.838.500 – microscopy, energy-filtering transmission electron MeSH E05.196.867.851 – spectroscopy, near-infrared MeSH E05.196.867.877 – spectrum analysis, mass MeSH E05.196.867.877.500 – mass fragmentography MeSH E05.196.867.877.600 – spectrometry, mass, electrospray ionization MeSH E05.196.867.877.750 – spectrometry, mass, fast atom bombardment MeSH E05.196.867.877.755 – spectrometry, mass, matrix-assisted laser desorption-ionization MeSH E05.196.867.877.760 – spectrometry, mass, secondary ion MeSH E05.196.867.890 – spectrum analysis, raman
Sources: en.wikipedia.org
This appeared to be dependent on proteasomal degradation of FoxM1, as expression of a FoxM1 mutant lacking a degron rescued the effects of OGT knockdown. FoxM1 was found not to be directly modified by O-GlcNAc, suggesting that hyper-O-GlcNAcylation of FoxM1 regulators impairs FoxM1 degradation. Targeting OGT also lowered levels of FoxM1-regulated proteins associated with cancer invasion and metastasis (MMP-2 & MMP-9), and angiogenesis (VEGF). O-GlcNAc modification of cofilin S108 has also been reported to be important for breast cancer cell invasion by regulating cofilin subcellular localization in invadopodia.
== History == MMPs were described initially by Jerome Gross and Charles Lapiere in 1962, who observed enzymatic activity (collagen triple helix degradation) during tadpole tail metamorphosis (by placing a tadpole tail in a collagen matrix plate). Therefore, the enzyme was named interstitial collagenase (MMP-1). Later, it was purified from human skin (1968), and was recognized to be synthesized as a zymogen. The "cysteine switch" was described in 1990.
Clonazepam, sold under the brand name Klonopin among others, is a benzodiazepine medication used to prevent and treat anxiety disorders, seizures, and akathisia, with some evidence supporting use in treatment of mania due to bipolar disorder. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. It is typically taken orally (swallowed by mouth) but is also used intravenously. Effects begin within one hour and last between eight and twelve hours in adults. Common side effects may include sleepiness, weakness, poor coordination, difficulty concentrating, and agitation. Clonazepam may also decrease memory formation. Long-term use may result in tolerance, dependence, and life-threatening withdrawal symptoms if stopped abruptly. Dependence occurs in one-third of people who take benzodiazepines for longer than four weeks. The risk of suicide increases, particularly in people who are already depressed. Use during pregnancy may result in harm to the fetus. Clonazepam binds to GABAA receptors, thus increasing the effect of the chief inhibitory neurotransmitter γ-aminobutyric acid (GABA). Clonazepam was patented in 1960 and approved in 1975 in the United States from Roche. It is available as a generic medication. In 2023, it was the 62nd most commonly prescribed medication in the United States, with more than 10 million prescriptions. In many areas of the world, it is commonly used as a recreational drug.
It was part of a series of twenty performances titled Hellfest from Home, recorded shortly before at the festival site in Clisson, France. That same month, Hangman's Chair were part of the lineup for the second and final edition of the online metal music festival Slay at Home, organised by Frank Godla, co-owner of Metal Injection. Slay at Home aimed to raise funds for MusiCares, the Cancer Research Institute, the Iggy Fund and the National Alliance on Mental Illness. In early October 2021, the band released the single "Loner" with a music video. Another single titled "An Ode To Breakdown" followed in November, accompanied by a live video taken from the at-home edition of Hellfest. During the recording sessions for their upcoming album, Hangman's Chair had set aside two songs, including "Judge Penitent". It was released as a single at the beginning of December and became the theme music for the fifth season (2021) of Gang Stories, a Deezer-produced podcast narrated by NTM rapper JoeyStarr.
Sources: en.wikipedia.org
Yes, the terms are generally interchangeable. Lyophilization is more common in pharmaceutical and laboratory contexts, while freeze-drying appears widely in food science and general writing. Both describe removal of solvent by sublimation under vacuum after freezing.
Reduced pressure keeps the process below the triple point of water, so ice can sublimate directly to vapor. It also lowers the temperature needed for drying, which helps preserve heat-sensitive materials. Without vacuum, melting or boiling could occur instead of controlled sublimation.
The rate depends on heat transfer to the product and mass transfer of vapor through the dried layer. A cold condenser, adequate vacuum, and suitable shelf temperature all influence speed. Formulation properties such as solid content and collapse temperature also set practical limits.
Conventional drying uses heat to evaporate water from a material, while lyophilization freezes the material and removes water by sublimation under vacuum. This avoids the liquid phase and reduces thermal damage to sensitive substances. The result is a porous cake that reconstitutes quickly.