PCR Setup Protocol¶

Using Solarbio 2×Taq PCR MasterMix (PC1150). This protocol is suitable for routine genotyping, colony PCR, and amplicon generation from genomic DNA, plasmid DNA, or cDNA.

Materials Required¶

Item	Recommended Product	Alternative
2×Taq PCR MasterMix	PC1150 (Solarbio)	—
Forward primer (10 μM)	User-supplied	Desalted or HPLC-purified
Reverse primer (10 μM)	User-supplied	Desalted or HPLC-purified
Template DNA	User-prepared (see concentration guide below)	—
Nuclease-free water	Solarbio R1600	DEPC-treated water
PCR tubes (0.2 mL)	Thin-wall, flat-cap, DNase/RNase-free	0.2 mL strip tubes or 96-well plate
Thermal cycler	Any standard model (Bio-Rad T100, ABI Veriti, Eppendorf Mastercycler)	—
Ice	—	Cold block

Template DNA Concentration Guide¶

Template Type	Recommended Amount per 50 μL	Typical Purity Requirement
Genomic DNA (mammalian)	10–100 ng	A₂₆₀/A₂₈₀ 1.8–2.0
Genomic DNA (bacterial)	10–100 ng	A₂₆₀/A₂₈₀ 1.8–2.0
Plasmid DNA	0.1–10 ng	A₂₆₀/A₂₈₀ 1.8–2.0
cDNA	0.1–1 μL (from 20 μL RT reaction)	—
Colony lysate	1–2 μL (supernatant from 50 μL water boil, 10 min)	—
Viral DNA	1–10 ng	—

Protocol¶

Step 1: Thaw and Mix¶

Thaw the 2×Taq PCR MasterMix, primers, and template on ice. Vortex each briefly (2–3 s) and centrifuge (5 s, 10,000×g) to collect contents. Keep all components on ice throughout setup to prevent premature polymerase activity and primer-dimer formation.

Time: 5 min.

Step 2: Calculate and Prepare Master Mix¶

Calculate the total number of reactions including a no-template control (NTC) and at least 10% excess volume for pipetting loss. Prepare a master mix without template:

Component	Volume per 50 μL Reaction	Per 10 Reactions (incl. NTC)	Per 20 Reactions (incl. NTC)
2×Taq PCR MasterMix	25 μL	275 μL	550 μL
Forward primer (10 μM)	1 μL	11 μL	22 μL
Reverse primer (10 μM)	1 μL	11 μL	22 μL
Nuclease-free water	18 μL	198 μL	396 μL
Total master mix	45 μL	495 μL	990 μL

Note: For 2×Taq Plus (PC1155), 2×Taq HotStart (PC1160), and 2×High-Fidelity (PC1165), use the same volume ratios unless otherwise specified on the product label.

Time: 2 min.

Step 3: Distribute Mix¶

Vortex the master mix gently for 2 s. Dispense 45 μL into each PCR tube or well. Change tips between each tube to avoid cross-contamination.

Precaution: If using a 96-well plate, seal before proceeding to template addition. Use a fresh seal for template addition.

Time: 2 min.

Step 4: Add Template¶

Add 5 μL template DNA to each tube. For the NTC, add 5 μL nuclease-free water. Close tube caps immediately after adding template. For colony PCR: pick a single colony with a sterile pipette tip, streak on a replica plate, then dip the tip into the PCR tube.

Precaution: Change gloves after handling template DNA. Use positive-displacement pipettes for viscous genomic DNA.

Time: 3 min.

Step 5: Place in Thermal Cycler¶

Centrifuge tubes briefly (5 s) to collect liquid at the bottom. Transfer to the thermal cycler and start the program.

Step 6: Thermocycling¶

Select the program below based on your application:

Standard Protocol (default)¶

Step	Temperature	Time	Cycles
Initial denaturation	95°C	3 min	1
Denaturation	95°C	30 s	30–35
Annealing	Tm − 5°C (typically 55–65°C)	30 s	30–35
Extension	72°C	30–60 s/kb	30–35
Final extension	72°C	5 min	1
Hold	4°C	∞	—

GC-Rich Template Protocol (GC content > 65%)¶

Step	Temperature	Time	Cycles
Initial denaturation	98°C	3 min	1
Denaturation	98°C	15 s	32–35
Annealing	60–68°C (use touchdown)	30 s	32–35
Extension	72°C	45 s/kb	32–35
Final extension	72°C	7 min	1
Hold	4°C	∞	—

Additives: Add DMSO to 3–5% (v/v) or betaine to 1 M final if GC > 70%.

Long Amplicon Protocol (> 3 kb)¶

Step	Temperature	Time	Cycles
Initial denaturation	95°C	3 min	1
Denaturation	95°C	20 s	30
Annealing	58–62°C	30 s	30
Extension	72°C	1 min/kb (incremental +10 s/cycle after cycle 20)	30
Final extension	72°C	10 min	1
Hold	4°C	∞	—

Use: 2×High-Fidelity PCR MasterMix (PC1165) for > 3 kb amplicons.

Touchdown Protocol (for difficult/specific targets)¶

Step	Temperature	Time	Cycles
Initial denaturation	95°C	3 min	1
Touchdown (step 1)	95°C, 30 s → 68°C, 30 s → 72°C, 30 s/kb	—	5
Touchdown (step 2)	95°C, 30 s → 65°C, 30 s → 72°C, 30 s/kb	—	5
Touchdown (step 3)	95°C, 30 s → 62°C, 30 s → 72°C, 30 s/kb	—	5
Touchdown (step 4)	95°C, 30 s → 59°C, 30 s → 72°C, 30 s/kb	—	5
Amplification	95°C, 30 s → 57°C, 30 s → 72°C, 30 s/kb	—	15–20
Final extension	72°C	5 min	1
Hold	4°C	∞	—

Primer Design Guidelines¶

Parameter	Recommended Value
Length	18–25 nt
GC content	40–60%
Tm	55–65°C (use nearest-neighbor calculation)
Tm difference (pair)	≤5°C
3′ end	End with G or C if possible (terminal GC clamp)
Avoid	3′ complementarity, long homopolymers (>4 nt), internal secondary structure (ΔG < −6 kcal/mol)
Amplicon length	100–3000 bp (standard Taq)
Concentration (final)	0.1–0.5 μM each primer
Hairpin stability	ΔG > −3 kcal/mol (check with OligoAnalyzer or Primer3)

Quality Checks During Protocol¶

Step	What to Verify	Expected Result
After PCR	Run 5 μL product on 1–2% agarose gel	Single band at expected size
NTC well	No template control	No detectable band after 35 cycles
Positive control	Known template with validated primers	Band at expected size
Gel marker	Ladder loaded alongside samples	All marker bands visible

Expected Results¶

PCR Outcome	Yield (per 50 μL)	Interpretation
Single bright band	200–500 ng	Successful amplification
Weak but single band	20–100 ng	Low yield — optimize template or cycles
Multiple bands	—	Non-specific — increase annealing temperature
Smear	—	DNA degradation or excess template
No product	—	See troubleshooting

Troubleshooting¶

Problem	Possible Cause	Solution
No amplification	Poor primer design	Redesign primers, check Tm
	Template degraded	Check template integrity by gel
	PCR inhibitor present	Dilute template 1:10, 1:100; add BSA 0.1 μg/μL
	Taq polymerase inactivated	Verify storage at -20°C; check expiration
	Annealing temperature too high	Lower 2–5°C; use gradient PCR
Non-specific bands	Annealing temperature too low	Increase by 2–5°C
	Too many cycles	Reduce to 28–30 cycles
	Primer dimer	Redesign primers, use hot-start
	Mg²⁺ concentration too high	Reduce to 2 mM (use MgCl₂ optimization)
Weak amplification	Insufficient template	Increase 2–5×
	Extension time too short	Increase to 1 min/kb
	Too few cycles	Increase to 38 cycles
	Primers degraded	Re-order or re-purify primers
Smear on gel	Excessive template	Dilute template
	Degraded template	Prepare fresh template
	Voltage too high during electrophoresis	Reduce to 5 V/cm
Primer-dimer present	Excessive primer	Reduce to 0.1–0.2 μM
	Low template	Increase template amount
	Room temperature setup	Keep all components on ice
Bands in NTC	Contamination	Use fresh water, filter tips; UV-decontaminate PCR hood

For product procurement: solarbio.store | solarbio.store