GelMA serves as a biomaterial scaffold that provides structural support for cell adhesion, proliferation, migration, and differentiation through its RGD peptide sequences (which promote cell adhesion) and MMP-degradable peptides (which enable enzymatic degradation by matrix metalloproteinases). [1]
This material primarily acts as an extracellular matrix-mimicking scaffold. Its target is not a specific single molecule but rather a broad range of adherent cells (e.g., fibroblasts, stem cells, endothelial cells) by providing integrin-recognizable Arginine-Glycine-Aspartic acid sequences and matrix metalloproteinase-sensitive sites, thereby supporting cell adhesion, proliferation, migration, and differentiation. In the presence of a photoinitiator (e.g., LAP), this material self-assembles into fibrous hydrogels, targets bioactive adhesion sites, and exerts inherent support for tissue cells and biodegradation activity.

GelMA scaffolds support the formation of multi-layered epidermis and growth of keratinocytes into functional multi-layered epidermis-type tissue. [1]
Electrospun GelMA fibrous scaffolds exhibit soft adjustable mechanical properties and controllable degradation properties. The diameter of GelMA fibers was 1.36 ± 0.27 μm before swelling and increased to 2.18 ± 0.52 μm after 24 h in PBS, with a water swelling ratio of approximately 600% (absorbing almost six times its own weight). GelMA scaffolds showed water permeability values of 2130 ± 160 L•m⁻²•h⁻¹•atm⁻¹ (GelMA-30), 1580 ± 110 L•m⁻²•h⁻¹•atm⁻¹ (GelMA-50), and 810 ± 90 L•m⁻²•h⁻¹•atm⁻¹ (GelMA-70). GelMA scaffolds exhibited elongation at break of 65% and were more flexible/compliant compared to crosslinked gelatin scaffolds. Degradation in vitro: GelMA-30 showed 22% mass loss over first 7 days and 69% by day 28; GelMA-50 showed 32% and 85%; GelMA-70 showed 39% and 88%. [2]
GelMA hydrogels supported human dermal fibroblast and human umbilical vein endothelial cell adhesion, proliferation, and migration. Live/Dead analysis showed >85% cell viability on GelMA after 1 day and >90% after 3 days. CCK-8 assay showed significantly higher metabolic activity on GelMA compared to crosslinked gelatin by day 3 (p<0.05). Cells seeded on GelMA scaffolds migrated to full depth (100 μm) after 7 days of cultivation, while cells on crosslinked gelatin only migrated to 60 μm depth. HUVECs on GelMA membranes connected to each other to form tube structures after 3 days of culture. Conditioned media from HDFs on GelMA showed increased protein levels of bFGF and VEGF compared to those on crosslinked gelatin (p<0.05). [2]
GelMA hydrogels with 6 wt% concentration were prepared by photocrosslinking. Swelling ratio reached equilibrium within 36 h. In vitro degradation with collagenase type II (1-2 U/mL): approximately 24.7% of the hydrogel remained after 20 days. Scanning electron microscopy showed disordered pores of 50-150 μm uniformly distributed. [4]
GelMA hydrogels supported chondrocyte viability and function. [4]

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In vitro, Blue Fluorescent GelMA crosslinks upon UV or blue light exposure with a photoinitiator (e.g., LAP) to form a three-dimensional hydrogel, providing a three-dimensional growth environment for cells. Experiments have confirmed that cells encapsulated within the hydrogel maintain high viability and exhibit good spreading morphology and proliferation capability. Its stable blue fluorescence signal allows direct observation of cell distribution and morphology via fluorescence microscopy (excitation/emission approximately 429/495 nm). This material has a scaffolding effect and can be used to design tissue analogs from vasculature to cartilage and bone, allowing cell proliferation and spreading.

GelMA electrospun fibrous scaffold implanted below the skin flap in a rat model significantly improved flap survival rate compared to control group, with more microvascular formation. At postoperative day 7, necrosis ratio was 23.8 ± 3.3% for GelMA group vs 30.1 ± 4.6% for gelatin group (p<0.05). Blood perfusion units were 832.2 ± 44.0 PU for GelMA vs 652.2 ± 48.1 PU for gelatin (p<0.05). CD68⁺ cell density (macrophage infiltration) was 38.0 ± 2.7 cells per high-power field for GelMA vs 51.3 ± 12.5 for gelatin (p<0.05). Microvessel density was 148.4 ± 19.3 microvessels/hot spot for GelMA vs 111.4 ± 14.8 for gelatin and 72.0 ± 12.9 for control (p<0.05). The GelMA membrane was almost fully biodegraded after 7 days implantation, while crosslinked gelatin membrane was still not fully biodegraded. [2]
In a mouse model of surgically induced osteoarthritis (anterior cruciate ligament transection), intra-articular injection of GelMA hydrogel alone (10 μL per week) showed mild protective effects. At 4 weeks post-surgery, OARSI score for GelMA-treated OA mice was significantly lower than untreated OA mice (p<0.05), but at 8 weeks, no significant difference was observed compared to untreated OA mice. [4]
In a full-thickness skin defect model, GelMA-based antibacterial electroactive injectable hydrogel (QCSP3/PEGS-FA1.5) significantly enhanced wound healing compared to commercial film dressing (Tegaderm™) and QCS hydrogel without polyaniline. At day 10, wound contraction was approximately 10% higher than control groups (p<0.01). At day 15, the hydrogel group still had a 5% lead in wound contraction (p<0.05). Granulation tissue thickness was approximately 200 μm thicker than control groups (p<0.01). The hydrogel upregulated growth factor expression: EGF (7.9× at day 5, 4.9× at day 10, 2× at day 15 vs commercial dressing), TGF-β (8.4×, 5.6×, 2.8×), and VEGF (10.6×, 8.4×, 4.9×). Collagen content was significantly increased at days 5, 10, and 15 (p<0.05). [3]

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In vivo, after implantation as a tissue engineering scaffold, Blue Fluorescent GelMA adapts to tissue defect sites and supports host cell infiltration and neovascularization. Its blue fluorescence properties enable tracking via small animal live imaging systems to monitor scaffold degradation and host integration without the need for additional labeling. Studies indicate that this material possesses good histocompatibility and shows efficacy in promoting tissue regeneration in models of cartilage, skin, vascular, and bone repair. The degree of methacrylation (e.g., 30%, 60%, 90%) can tune the in vivo degradation rate and mechanical properties of the material.

GelMA enzymatic degradation assay: Hydrogel samples were placed in centrifuge tubes with PBS containing 1-2 U/mL collagenase type II at 37°C. At predefined time points, hydrogels were removed, frozen, lyophilized, and mass loss was determined as the ratio of final weight to original dry weight. Approximately 24.7% of GelMA hydrogel remained after 20 days of collagenase treatment. [4]
No classical enzyme/receptor binding assays are applicable as GelMA is a biomaterial scaffold, not a pharmacological agent. [1,2,3,4]

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1. Hydrogel Preparation: Dissolve the Blue Fluorescent GelMA lyophilized powder in pre-warmed (e.g., 37-50°C) sterile PBS or cell culture medium to prepare a solution of desired concentration (e.g., 5-15% w/v). 2. Crosslinking: Add photoinitiator LAP (e.g., 0.25% w/v), mix well, inject into molds, and cure under UV light (365nm) or blue light for several minutes. 3. Enzymatic Degradation: Weigh the formed hydrogel or place it in a buffer solution containing Collagenase I or Matrix Metalloproteinases, and incubate at 37°C. 4. Observation: Quantitatively assess the degradation rate by monitoring the attenuation of blue fluorescence intensity (excitation 429 nm/emission 495 nm) or the change in gel remaining weight. The fluoraldehyde assay can also be used to assess the degree of modification by detecting blue fluorescent derivatives generated from the reaction between lysine residues and fluoraldehyde reagents.

GelMA - Cell viability assay (Live/Dead): Human dermal fibroblasts and human umbilical vein endothelial cells were seeded on crosslinked gelatin and GelMA electrospun membranes. Live/Dead staining was performed according to manufacturer's instructions at days 1 and 3. Green fluorescent cells were live, red fluorescent cells were dead. Viability was calculated by quantifying live and dead cells. >85% viability on GelMA at day 1 and >90% at day 3. [2]
Cell proliferation assay (CCK-8): Cells on different membranes were washed with PBS, culture medium (1000 μL) was added, then 100 μL of CCK-8 reagent was added and incubated at 37°C for 2 h. Absorbance was measured at 450 nm using a microplate reader. Metabolic activity increased with time; by day 3, CCK-8 values within GelMA groups were significantly greater than gelatin group (p<0.05). [2]
Cell morphology and attachment: Cells on membranes were fixed with 4% glutaraldehyde for 2 h at 4°C, dehydrated by ethanol series, and observed by SEM. For fluorescence staining, cells were fixed in 4% paraformaldehyde, permeabilized with 0.1% Triton X-100, blocked with 1% BSA, stained with phalloidin-FITC (50 mg/mL) for cell filaments and DAPI for nuclei, and imaged by fluorescence microscopy. HDFs and HUVECs on GelMA showed elongated morphology with filamentous projections; HUVECs formed tube structures along fibers after 3 days. [2]
Cell migration assay: Cells seeded on scaffolds were stained with phalloidin-Alexa Fluor 488 for cell filaments (green). Mean migration depth was determined as average depth where cells were detected, ignoring cells on scaffold surface. After 7 days, cells on GelMA migrated to full depth (100 μm), while cells on crosslinked gelatin only migrated to 60 μm. [2]
Matrigel tubulation and cell secretion assay: GelMA membranes carrying HDFs were placed in upper chamber of transwell plates (0.4 μm pore filters) with 400 μL serum-free medium. Calcein-labeled HUVECs were seeded on growth factor-reduced Matrigel-coated 12-well plates (10⁵ cells/well) with 1000 μL serum-free medium. After 6 and 12 h, HUVEC tubules were counted. Conditioned media from HDFs were collected and VEGF and bFGF levels quantified by ELISA. HUVECs on GelMA-conditioned media showed 40.4 tubules per power field vs 11.8 for gelatin (p<0.05). [2]
Chondrocyte culture and gene expression analysis: Mouse articular chondrocytes were maintained in DMEM with 10% FBS. Cells were lysed in TRIzol, mRNA extracted, and real-time PCR performed using SYBR Green with a Light Cycler. Primers used: COL2A1, Acan, MMP13, ADAMTS-5, with actin as reference. Western blotting was performed for LC3, MMP13, COL2A1, ADAMTS-5, and aggrecan. SIN treatment (10 mM) in IL-1β-stimulated chondrocytes decreased MMP13 and ADAMTS-5 mRNA and increased COL2A1 and aggrecan, while increasing LC3-II expression. [4]

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1. Prepare Cell-Material Mixture: Gently mix cells (e.g., density 1×10⁶/mL) with pre-warmed (37°C) sterile Blue Fluorescent GelMA precursor solution (e.g., 5-15% w/v). 2. Crosslinking: After adding the photoinitiator LAP, dispense the cell-material mixture onto culture plates and expose to UV or blue light for seconds to minutes to induce gelation. 3. Culture: Add pre-warmed complete medium to the wells and incubate at 37°C in a 5% CO₂ incubator. 4. Viability Assay: At set time points (e.g., Day 1, 3, 7), perform live/dead staining using Calcein-AM (stains live cells green) and PI (stains dead cells red), and observe under a confocal microscope. 5. Analysis: As the material itself emits blue fluorescence, it is recommended to use other fluorescence channels (e.g., red or far-red) for cell morphology and activity analysis to avoid crosstalk. Alamar Blue assay can also be used to measure cell metabolic activity (excitation 530 nm/emission 590 nm).

GelMA - Rat full-thickness skin wound healing model: Rats received full-thickness skin defects. Electrospun GelMA fibrous scaffolds were implanted below the skin flap. At day 7 post-operation, animals were anesthetized, and surviving and necrotic areas were photographed. Necrotic area was quantified as percentage of total flap area using Image-Pro Plus software. Blood perfusion was assessed by laser Doppler flowmetry at controlled temperature (28-30°C). Tissue samples were harvested for histological assessment (H&E, Masson's trichrome, CD68 immunohistochemistry, CD31 immunofluorescence). [2]
Mouse osteoarthritis model (ACLT): Eight-week-old male C57BL/6 mice underwent anterior cruciate ligament transection surgery to both knees. Ten days after ACLT, intra-articular injections of GelMA hydrogel (10 μL per week) were administered. Mice were sacrificed at 4 and 8 weeks after ACLT. Distal femurs were dissected, embedded in paraffin, sectioned (8 μm), stained with safranin-O, and evaluated by OARSI scoring. Immunohistochemistry was performed for LC3, MMP13, COL2A1, ADAMTS-5, and aggrecan. Immunofluorescence for LC3 was also performed with DAPI nuclear staining. [4]
Rat model for injectable hydrogel wound dressing: A full-thickness skin defect model was used. Hydrogel QCSP3/PEGS-FA1.5 was prepared by mixing quaternized chitosan-g-polyaniline (3.5 wt%) and benzaldehyde-functionalized PEGS-FA (1.5 wt%) in PBS. Gelation time was 86-374 seconds depending on crosslinker concentration. The hydrogel was injected into wound sites. Wound closure was monitored at days 5, 10, and 15. Granulation tissue thickness, collagen content (hydroxyproline assay), and growth factor expression (EGF, TGF-β, VEGF by qPCR) were evaluated. [3]

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1. Material Preparation: Mix Blue Fluorescent GelMA precursor solution with photoinitiator LAP. Pre-fabricate hydrogel scaffolds via photocrosslinking under sterile conditions, or keep the mixture in liquid form for in-situ injection. 2. Animal Model: Establish a corresponding animal injury model (e.g., dorsal skin defect in nude mice, subcutaneous implantation model, or bone defect model). 3. Implantation/Injection: Implant the hydrogel scaffold into the defect site, or subcutaneously inject the liquid mixture followed by transdermal blue light irradiation for in-situ crosslinking. 4. In Vivo Imaging Tracking: At various time points post-implantation (e.g., Week 1, 2, 4), use a small animal in vivo imaging system with excitation at 429 nm and emission at 495 nm to capture fluorescence signals, monitoring scaffold morphology and degradation. 5. Histological Analysis: Euthanize animals at the experimental endpoint, excise the explant and surrounding tissue, and perform H&E, Masson's trichrome, or immunohistochemical staining on sections to observe tissue regeneration, collagen deposition, and inflammatory response.

GelMA is not a pharmacological agent with traditional ADME properties. As a biomaterial scaffold, its degradation profile is characterized by enzymatic degradation via matrix metalloproteinases. The degree of methacryloyl substitution controls degradation rate: higher DS leads to longer degradation period. In vitro degradation with collagenase: approximately 24.7% of GelMA hydrogel remained after 20 days. [4]
In vivo degradation: GelMA electrospun membrane was almost fully biodegraded after 7 days implantation in a rat model, while crosslinked gelatin membrane remained not fully biodegraded. [2]
Swelling ratio: GelMA hydrogels reached equilibrium swelling within 36 h in PBS. [4]

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As a macromolecular biomaterial, the pharmacokinetic behavior of Blue Fluorescent GelMA primarily manifests as the in vivo degradation and metabolism of the scaffold, rather than the traditional ADME (Absorption, Distribution, Metabolism, Excretion) of small molecule drugs. Its degradation kinetics are mainly governed by hydrolysis and enzymatic degradation mediated by matrix metalloproteinases. The degradation rate can be tuned by altering the degree of methacrylation (e.g., 30%, 60%, 90%) or crosslinking density. The resulting gelatin fragments and covalently bound blue fluorescent molecules are subsequently absorbed or metabolized by the body. The attenuation of the fluorescence signal serves as an indirect indicator for evaluating its in vivo half-life, and the in vivo clearance curve can be fitted by detecting fluorescence intensity at various time points using in vivo imaging systems.

GelMA hemolytic activity test: Hydrogel groups showed light yellow supernatant similar to negative control (TCP), while positive control (Triton X-100) was bright red, indicating no hemolytic activity. Hemolysis ratio results confirmed good blood compatibility. [3]
Cytotoxicity evaluation by direct contact test: All GelMA-based hydrogels showed >95% cell viability compared to TCP group (p>0.05). LIVE/DEAD staining showed cells were green with spindle-like morphology similar to TCP control, with few dead cells due to normal metabolism and apoptosis. [3]
Inflammatory response in vivo: CD68⁺ cell density (macrophage infiltration) at day 7 post-implantation was 38.0 ± 2.7 cells per high-power field for GelMA group, which was significantly lower than crosslinked gelatin group (51.3 ± 12.5) (p<0.05), indicating less inflammation with GelMA. [2]
No mortality or significant adverse effects were reported in any of the animal studies at the tested concentrations and doses. [2,3,4]

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Based on the biological origin and chemical modification characteristics of GelMA, Blue Fluorescent GelMA generally exhibits good biosafety. Cytotoxicity assays indicate that the uncrosslinked precursor solution shows no significant toxicity to cells at low concentrations, and the free radicals generated during the photocrosslinking process can be minimized using low-toxicity photoinitiators (e.g., LAP) and tissue-friendly light sources (e.g., 405 nm visible light). In vivo toxicological studies show that implantation of fully crosslinked hydrogels does not cause significant acute inflammatory responses, systemic toxicity, or major organ abnormalities. The degradation products are gelatin fragments and covalently bound fluorescent molecules, which are safely metabolized, exhibiting low immunogenicity. It is recommended to store at -20°C or 4°C protected from light and sealed to maintain stable fluorescence properties.

[1]. Biomedical applications of gelatin methacryloyl hydrogels. Engineered Regeneration, 2021, 2: 47-56.

[2]. Electrospun photocrosslinkable hydrogel fibrous scaffolds for rapid in vivo vascularized skin flap regeneration. Adv. Funct. Mater. 2017, 27, 1604617.

[3]. Antibacterial anti-oxidant electroactive injectable hydrogel as self-healing wound dressing with hemostasis and adhesiveness for cutaneous wound healing. Biomaterials. 2017 Apr;122:34-47.

[4]. Intra-articular delivery of sinomenium encapsulated by chitosan microspheres and photo-crosslinked GelMA hydrogel ameliorates osteoarthritis by effectively regulating autophagy. Biomaterials. 2016 Mar;81:1-13.

GelMA was developed in 2000 by Van den Bulcke et al. and has been optimized over two decades. It overcomes limitations of gelatin hydrogels: (1) basic gelatin is soluble at body temperature, limiting direct application as cell carrier; (2) glutaraldehyde crosslinking of gelatin is cytotoxic, time-consuming, and highly uncontrollable. GelMA can be constructed into various scaffold forms: 3D scaffold, injectable gel, bio-printed scaffold (extrusion-based and photomask-based), and electrospun fibrous membrane. [1]
Applications include wound dressing, cartilage regeneration, bone regeneration, tendon regeneration, vascular regeneration, cardiovascular engineering, neural engineering, drug delivery, organ-on-a-chip, and biosensing. [1]
GelMA can be blended with other polymers (e.g., bovine serum albumin, host-guest supramolecular systems) to endow self-healing properties. The double solidification method (low temperature + photo-crosslinking) makes GelMA a promising bioink for extrusion bioprinting. [1]
In osteoarthritis treatment, GelMA served as a vehicle for intra-articular delivery of sinomenium-loaded chitosan microspheres. The combination of GelMA with controlled-release microspheres showed sustained drug release and ameliorated degenerative changes. [4]
In wound healing applications, incorporation of polyaniline into GelMA-based hydrogels provided electroactivity, antioxidant activity (DPPH scavenging >84%), and enhanced wound healing through upregulation of VEGF, EGF, and TGF-β. [3]

White to off-white solids at room temperature

GelMA, 90% methacrylation, blue fluorescent

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O: ~100 mg/mL

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)