A practical reference on sublimation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-18. Anything still debated is marked as such rather than presented as settled.
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.
The physics of lyophilization depends on phase boundaries and heat and mass transfer. During primary drying, heat supplied to the product must equal the latent heat of sublimation, while water vapor moves through the drying cake to the condenser. If shelf temperature or pressure is set too high, the ice front can exceed the collapse temperature, causing meltback or pore collapse. If conditions are too cold, drying slows and costs rise. Formulation excipients, vial geometry, and freezing rate alter these limits.
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.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying; lyophilisation; cryodesiccation | Regional spelling and historical terms. |
| Primary drying pressure | 0.05-0.5 mbar (5-50 Pa) | Kept below the triple point of water; product-specific. |
| Shelf temperature range | -40 to +40 °C | Freezing, primary, and secondary stages use different set points. |
| Cycle duration | 12-72 hours | Depends on fill volume, formulation, and equipment. |
| Condenser temperature | -50 to -80 °C | Must remain below the product's ice temperature. |
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.
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.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Ansuvimab was developed by the Vaccine Research Center with support of the United States National Institutes of Health and the Defense Advanced Projects Agency. The heavy and light chain sequences of ansuvimab mAb were cloned into CHO cell lines to enable large-scale production of antibody product for use in humans. In early 2018, a Phase 1 clinical trial of ansuvimab's safety, tolerability and pharmacokinetics was conducted by Dr. Martin Gaudinski within the Vaccine Research Center Clinical Trials Program that is led by Dr. Julie E. Ledgerwood. The study was performed in the United States at the NIH Clinical Center and tested single dose infusions of ansuvimab infused over 30 minutes. The study showed that ansuvimab was safe, had minimal side effects and had a half-life of 24 days. A license for ansuvimab was obtained by Ridgeback Biotherapeutics in 2018, from the National Institutes of Health-National Institute of Allergy and Infectious Diseases. Ansuvimab was given orphan drug status in May 2019 and March 2020.
An analytical ultracentrifuge has a light source and optical detectors. To allow the light to pass through the analyte during the ultracentrifuge run, specialized cells are required which have to meet high optical standards as well as to resist the centrifugal forces. Each cell consists of a housing, two windows made from optically pure quartz glass, and a centrepiece with one or two sectors and filling holes for the sector(s), closed with a screw plug in the housing. These cell are placed into a rotor cavity with a continuous bore, with a collar at the bottom to retain the cell. By applying specific equipment and adapting measurement parameters several types of experiments can be performed. Most common AUC experiments are sedimentation velocity and sedimentation equilibrium experiments.
In order for a protonated acid to lose a proton, the pH of the system must rise above the pKa of the acid. The decreased concentration of H+ in that basic solution shifts the equilibrium towards the conjugate base form (the deprotonated form of the acid). In lower-pH (more acidic) solutions, there is a high enough H+ concentration in the solution to cause the acid to remain in its protonated form. Solutions of weak acids and salts of their conjugate bases form buffer solutions. To determine the concentration of an acid in an aqueous solution, an acid–base titration is commonly performed. A strong base solution with a known concentration, usually NaOH or KOH, is added to neutralize the acid solution according to the color change of the indicator with the amount of base added. The titration curve of an acid titrated by a base has two axes, with the base volume on the x-axis and the solution's pH value on the y-axis. The pH of the solution always goes up as the base is added to the solution.
Before amylin deposition was associated with diabetes, already in 1901, scientists described the phenomenon of "islet hyalinization", which could be found in some cases of diabetes. A thorough study of this phenomenon was possible much later. In 1986, the isolation of an aggregate from an insulin-producing tumor was successful, a protein called IAP (Insulinoma Amyloid Peptide) was characterized, and amyloids were isolated from the pancreas of a diabetic patient, but the isolated material was not sufficient for full characterization. This was achieved only a year later by two research teams whose research was a continuation of the work from 1986.
Sources: en.wikipedia.org
AH receptor-interacting protein (AIP) also known as aryl hydrocarbon receptor-interacting protein, immunophilin homolog ARA9, or HBV X-associated protein 2 (XAP-2) is a protein that in humans is encoded by the AIP gene. The protein is a member of the FKBP family. AIP may play a positive role in aryl hydrocarbon receptor-mediated signalling possibly by influencing its receptivity for ligand and/or its nuclear targeting. AIP is the cellular negative regulator of the hepatitis B virus (HBV) X protein. Further, it's been known to suppress antiviral signaling and the induction of type I interferon by targeting IRF7, a key player in the antiviral signal pathways. AIP consists of an N-terminal FKBP52 like domain and a C-terminal TPR domain. AIP mutations may be the cause of a familial form of acromegaly, familial isolated pituitary adenoma (FIPA). Somatotropinomas (i.e. GH-producing pituitary adenomas), sometimes associated with prolactinomas, are present in most AIP mutated patients.
Antibody–drug conjugates or ADCs are a class of bioconjugates and immunoconjugates. ADCs are composed of an antibody linked to a cytotoxic (anticancer) "payload" or drug. Among treatment options for cancer, chemotherapy is most widely used. Its main limitation is low target specificity. Unlike chemotherapy, ADCs target tumor cells while sparing healthy cells. As of 2019, some 56 pharmaceutical companies were developing ADCs. ADCs combine the targeting properties of monoclonal antibodies with the cancer-killing capabilities of cytotoxic drugs, designed to discriminate between healthy and diseased tissue.
AlphaKnot complements KnotProt, a database focused on experimentally determined protein structures and their topological features. KnotProt provides detailed descriptions of knots, slipknots, and related entanglements in experimentally characterized proteins, whereas AlphaKnot was developed primarily to examine the much larger population of structures generated by modern protein-structure prediction methods. AlphaKnot has been used to investigate the frequency and distribution of knots in protein families and to identify previously uncharacterized topological architectures. Large-scale analyses of AlphaFold structures have identified unusual knot types and proteins containing multiple knots, while comparison with experimentally determined structures has provided examples in which unusual predicted topologies were subsequently confirmed experimentally. The database can therefore be used both as a source of candidate knotted proteins for experimental investigation and as a computational tool for examining the relationship between protein sequence, structure, and topology.
GOT1/cAST, the cytosolic isoenzyme derives mainly from red blood cells and heart. GOT2/mAST, the mitochondrial isoenzyme is present predominantly in liver. These isoenzymes are thought to have evolved from a common ancestral AST via gene duplication, and they share a sequence homology of approximately 45%. AST has also been found in a number of microorganisms, including E. coli, H. mediterranei, and T. thermophilus. In E. coli, the enzyme is encoded by the aspCgene and has also been shown to exhibit the activity of an aromatic-amino-acid transaminase (EC 2.6.1.57).
From 2011, new cars should have brake assist system in the EU, according to The Pedestrian Protection Regulation (EC) 78/2009. Starting in 2012, all cars under 10,000 lbs. sold in the US are required to have Electronic Stability Control. In 2014, ESP (Electronic Stability Program) and TPMS became mandatory in the European Union, with also the driver seat belt reminder and the ISOFIX system, under General Safety Regulation (EC) No 661/2009. In 2015, recognizing that safer roads are a shared responsibility, Together for Safer Roads (TSR) was formally launched to align the private sector's road safety efforts with the United Nations Decade of Action for Road Safety. In 2016 and 2017, ABS became mandatory on motorcycles in the EU. In 2018, eCall became mandatory in the EU, and reverse camera in the US. In 2019, the EU legislated to revise the General Safety Regulation (GSR), the revision includes the following automotive safety features:
Sources: en.wikipedia.org
Simple drying usually removes water by evaporation from a liquid or solid, often with heat. Lyophilization first freezes the material and then removes ice by sublimation under vacuum. This avoids prolonged exposure to liquid water and high temperatures.
Reduced pressure lowers the boiling point of water and allows ice to sublime at temperatures below freezing. It also helps remove water vapor from the product toward the condenser. The exact pressure is chosen to stay below the triple point of water.
No. Materials with low solids content or high volatile solvents may form weak or collapsed cakes. Some proteins and cells require stabilizers to survive freezing and drying stresses. Feasibility depends on formulation and process design.
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.